Seminars and Conferences
2024
2024
Prof. Nick Auyeung
25.06.2024Development of Materials and Reactors for Thermochemical Energy Storage
Oregon State University (EEUU)
Place: Salón de Grados de cicCartuja2
Thermochemical Energy Storage (TCES) has been identified as a promising solution for scalable, long duration energy storage. TCES is essentially the utilization of reversible reactions, which have inherently higher energy storage densities compared to sensible or latent heat storage. Thermal energy for charging such a system can be derived from the sun, waste heat, or electrical heating. In this presentation, we share our recent TCES work for both Concentrated Solar Power (CSP) and industrial applications, including our development of a 1-kW prototype TCES reactor-heat exchanger for discharge of stored chemical energy to a working fluid. The talk will include discussion of the fundamental challenges remaining to be solved to achieve technical and commercial viability.
Dra. Olga Sacco
08.03.2024Polymer/photocatalyst composites for removal of organic pollutants and selective oxidation of benzene to phenol and CO2 valorization
Dipartamento di Chimica e Biologia "A. Zambelli". Universidad de Salerno (Italia)
Place: Salón de Grados de cicCartuja II
2023
2023
Prof. Valeria Nicolosi
14.09.2023Nanomaterials at the frontline of the energy challenge
Trinity College Dublin, School of Chemistry, CRANN, AMBER and IForm Centres, Dublin 2, Ireland
Place: Salón de Grados cicCartuja II
Liquid phase exfoliation has been proved to be a cheap, scalable method for the mass production of 2D sheets. This talk will first discuss the galaxy of existent layered materials, with emphasis on synthesis, liquid-phase exfoliation, and characterization, focusing on some key applications recently developed in our laboratories, ranging from energy storage to printed electronics. We will for example discuss how two-dimensional nanomaterials can be formulated in aqueous and organic viscous inks for extrusion printing, inkjet printing, and aerosol jet 3D printing, and demonstrate direct printing on various substrates. The additive- and binary solvent-free inks do not show coffee ring effect, enabling high-resolution printing without substrate pre-treatment. The resulting printed micro-supercapacitors showcase excellent charge storage performance, including areal capacitance up to 100 mF/cm2 and volumetric capacitance up to 800 F/cm3 in protic gel electrolyte, coupled with long lifetime and good flexibility. The versatile direct-ink-printing technique highlights the promise of 2D nanomaterials functional inks for scalable fabrication of easy-to-integrate components of printable electronics. In this talk we will also demonstrate how such inks can be used to develop novel nanomaterials-based battery solutions.
Increasing the energy storage capability of batteries necessitates maximization of their areal capacity. This requires thick electrodes performing at near-theoretical specific capacity. However, achievable electrode thicknesses are restricted by mechanical instabilities, with high-thickness performance limited by the attainable electrode conductivity. Here we show that forming a segregated network composite of carbon nanotubes with a range of lithium storage materials (for example, silicon, graphite, and metal oxide particles) suppresses mechanical instabilities by toughening the composite, allowing the fabrication of high-performance electrodes with thicknesses of up to 800 μm. Such composite electrodes display conductivities up to 1 × 104 S m−1 and low charge-transfer resistances, allowing fast charge-delivery and enabling near-theoretical specific capacities, even for thick electrodes. The combination of high thickness and specific capacity leads to areal capacities of up to 45 and 30 mAh cm−2 for anodes and cathodes, respectively. Combining optimized composite anodes and cathodes yields full cells with state-of-the-art areal capacities (29 mAh cm−2) and specific/volumetric energies (480 Wh kg−1 and 1,600 Wh l−1).
Figure 1: Printed devices based on MXenes inks.
Prof. Enrique Valera
29.06.2023Dried whole blood as a material for the detection of pathogens
Universidad de Illinois Urbana-Champaign (EEUU)
Place: Salón de Grados cicCartuja II
We introduce a new approach to blood-based diagnostics where large blood volumes can be rapidly dried, resulting in inactivation of the inhibitory components in blood. In this approach thermal treatments generate a physical microscale and nanoscale fluidic network inside the dried matrix to allow access to target nucleic acid. High heme background is confined to the solid phase, while amplicons are enriched in the clear supernatant (liquid phase), giving fluorescence change comparable to purified DNA reactions. We demonstrate single-molecule sensitivity using a LAMP reaction in our platform and detect a broad spectrum of pathogens, including MRSA, MSSA, E.Coli and Candida albicans from whole blood with a limit of detection of 1.2 CFU/mL in <2.5 h
2022
2022
Richard (YongQing) Fu
20.12.2022Smart acoustofluidic platform based on thin film acoustic wave technology
Faculty of Engineering and Environment, Northumbria University, Newcastle, UK
Place: Salón de Grados cicCartuja II
This talk will foucs on acoustofludics platform and lab-on-chip applications based on piezoelectric thin film acoustic wave technology, which shows a broad range of functions such as biosensing, particle/cell concentrating, sorting/patterning, pumping, nebulisation, heating and jetting. Integrated acoustic wave sensing/microfluidic devices have been fabricated by depositing these piezoelectric films onto a number of substrates such as silicon, ceramics, diamond, quartz, glass, and more recently also polymer, metallic foils and bendable glass/silicon for making flexible devices. Such thin film acoustic wave devices have great potentials for implementing integrated, disposable, or bendable/flexible devices into various sensing and actuating applications, using portable, wireless, flexible and remotely controlled acoustic wave devices.
João Carlos Mesquita Coelho
21.10.2022The road to flexible and sustainable nanomaterials-based energy storage devices
CENIMAT|i3N – NOVA School of Science and Technology (FCT-NOVA), Costa da Caparica, Portugal
Place: Salón de Grados del cicCartujaII
In the last few years, a lot of interest has been shown in nanomaterials, which can exhibit enhanced or totally new properties when compared to their bulk counterparts.1–4 For instance, the confinement of charge and heat in two dimensional (2D) graphene results in outstanding electrical, optical and mechanical properties. Not surprisingly, a wide range of nanomaterials has been suggested for several industrial applications.5–7 Special attention has been given to the role of nanomaterials in the energy sector due to the ongoing climate change and transition to greener energy sources. In addition, the advent of digital manufacturing technologies, such as 3D, inkjet printing and laser process/patterning demonstrated a huge potential to disrupt and create technologies such as wearable electronics and flexible, stretchable portable devices. A key technical constraint for the large-scale utilization of these devices is energy autonomy, which requires the development of flexible energy sources/storage systems, such as micro-supercapacitors and thin-film Li/Na-ion batteries. Inks based on conductive nanomaterials are promising material platforms for these flexible devices. For instance, due to their superior mechanical and electrical properties, carbon nanotubes (CNTs) and graphene, can be implemented as efficient current collectors, thus removing the need for bulky/heavy metallic components, while nanomaterials are responsible for the energy storage process.8,9 In order to maximize the exploitation of these material properties, optimized inks, formulations and depositions methodologies must be designed and characterized. Considering the wider societal awareness towards environmental issues and on-going legislations, energy storage devices of the future will have to be based in efficient, eco-friendly, and sustainable manufacturing processes.
In this talk, I will exhibit the advantages of 2D based energy storage devices along with approaches for their sustainable fabrication. A special attention will be given to green solvents, such as cyrene, and biodegradable substrates such as paper and cork. The combination of nanomaterials and efficient eco-friendly manufacturing technologies will open the avenue for the large-scale production of ultra-light and thin flexible energy storage devices. Additionally, by defining a smart integration approach based on hybrid electronics the pro-posed methodology will further close the gap between conventional and flexible electronics.
- Chhowalla, M. et al. The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets. Nat. Chem. 5, 263–275 (2013).
- Coleman, J. N. Liquid Exfoliation of Defect-Free Graphene. Acc. Chem. Res. 46, 14–22 (2013).
- Coleman, J. N. et al. Two-Dimensional Nanosheets Produced by Liquid Exfoliation of Layered Materials. Science (80-. ). 331, 568–571 (2011).
- Nicolosi, V., Chhowalla, M., Kanatzidis, M. G., Strano, M. S. & Coleman, J. N. Liquid Exfoliation of Layered Materials. Science (80-. ). 340, 1226419 (2013).
- McAteer, D. et al. Liquid Exfoliated Co(OH) 2 Nanosheets as Low-Cost, Yet High-Performance, Catalysts for the Oxygen Evolution Reaction. Adv. Energy Mater. 8, 1702965 (2018).
- Coelho, J. et al. Manganese oxide nanosheets and a 2D hybrid of graphene-manganese oxide nanosheets synthesized by liquid-phase exfoliation. 2D Mater. 2, 025005 (2015).
- Jaśkaniec, S. et al. Low-temperature synthesis and investigation into the formation mechanism of high quality Ni-Fe layered double hydroxides hexagonal platelets. Sci. Rep. 8, 4179 (2018).
- Coelho, J., Kremer, M. P., Pinilla, S. & Nicolosi, V. An outlook on printed microsupercapacitors: Technology status, remaining challenges, and opportunities. Current Opinion in Electrochemistry vol. 21 69–75 (2020).
- Zhang, C. J. et al. Stamping of Flexible, Coplanar Micro-Supercapacitors Using MXene Inks. Adv. Funct. Mater. 28, 1705506 (2018).
- Kelly, A. G. et al. All-printed thin-film transistors from networks of liquid-exfoliated nanosheets. Science (80-. ). 356, 69–73 (2017).
- Lin, Y., Gao, Y., Fang, F. & Fan, Z. Recent progress on printable power supply devices and systems with nanomaterials. Nano Res. 11, 3065–3087 (2018).
Ibrahim Abdulhalim
26.09.2022Small scale high performance photonic devices for biomedical, agricultural, and environmental applications
Department of Electro-Optics and Photonics Engineering and The Ilse Katz Institute for Nanoscale Science and Technology, ECE School, Ben Gurion University, Israel
Place: Salón de Grados de cicCartujaII
Developments in nanotechnology, electronics, computing, algorithms, imaging, and fabrication technologies are assisting us in miniaturizing optical/photonic devices to become portable and suitable for point of care and field applications. During the last 10 years we have been working on different technologies for this purpose including full field optical coherence tomography, plasmonic sensors, and spectral/polarization control liquid crystal devices.
In this lecture I will review our miniaturized devices developed for these purposes including spectro-polarimetric imaging module based on unique liquid crystal devices demonstrated for skin cancer detection, plasmonic sensor with less than 1kg weight and small form factor demonstrated for detecting biomarkers, viruses, bacteria and other analytes, SERS sensors with ultrahigh enhancement, and more.
Selected publications:
- Lior Graham, Yitzhak Yitzhaky and I. Abdulhalim, Classification of skin moles from optical spectro-polarimetric images, J. Biomed. Optics 18, 111403 (2013).
- Sachin K. Srivastava, Atef Shalabney, I. Khalailah, Christoph Grüner, B. Rauschenbach, and I. Abdulhalim, SERS Biosensor using Metallic nanoSculptured Thin Films for the Detection of Endocrine Disrupting Compound Biomarker Vitellogenin, Small 10, 3579-3587 (2014).
- Avner Safrani and Ibrahim Abdulhalim, High speed 3D imaging using two wavelengths parallel phase shift interferometry, Optics Letters 40, 4651-4 (2015).
- Michael Ney and I. Abdulhalim, Ultrahigh polarimetric image contrast enhancement for skin cancer diagnosis using InN plasmonic nanoparticles in the THz range, J. Biomed. Optics 20, 125007(14p) (2015).
- Sachin K. Srivastava, Christoph Gruner, Dietmar Hirsch, Bernd Rauschenbach, Ibrahim Abdulhalim, Enhanced intrinsic fluorescence from carboxidized nano-sculptured thin films of silver and their application for label free dual detection of glycated hemoglobin, Optics Express 25, 4761-72 (2017).
- Andrey Nazarov, Boris Knyazer, Tova Lifshitz, Mark Schvartzman, Ibrahim Abdulhalim, Assessment of intraocular pressure sensing using an implanted reflective flexible membrane, J. Biomed. Opt., 22(4), 047001 (2017).
- Marwan J. Abuleil and Ibrahim Abdulhalim, Broadband ellipso-polarimetric camera utilizing tunable liquid crystal achromatic waveplate with improved field of view, Optics Express 27 (9) 12011-24 (2019).
- Dorin Harpaz, Brescia Koh, Robert S. Marks, Raymond C. S. Seet, Ibrahim Abdulhalim and Alfred I. Y. Tok, Point-of-Care Surface Plasmon Resonance Biosensor for Stroke Biomarkers NT-proBNP and S100β using a Functionalized Gold Chip with Specific Antibody, Sensors, 19, 2533(16p) (2019).
- Aabha Bajaj, Anand M. Shrivastav, Evgeny Eltzov, Noam Alkan, and Ibrahim Abdulhalim, Detection of necrotrophic DNA marker of anthracnose causing Colletotrichum gloeosporioides fungi in harvested produce using surface plasmon resonance, Talanta 235, 122776 (2021).b
Prof. Bruno Viana
27.04.2022Materials for bioimaging and nanothermometry at IRCP Chimie-ParisTech, France; focus on the control of the kinetics
PSL University IRCP Chimie-ParisTech
Place: Salón de Actos de Grados cicCartuja
In bioimaging, the development of luminescent materials in various shapes (from nanoparticles to single crystals) requires perfect materials with high fluorescence intensity but also with careful control of the defects which could affect the kinetic of the luminescence. For instance, afterglow should be avoided in the scintillator domain in order to obtain clear and fast images. In that case the defects/traps must be carefully controlled to avoid room temperature detrapping and afterglow. Furthermore, on the opposite case, there is a large interest for materials with long afterglow or persistent luminescence. Several new applications are envisioned with these materials such as emergency signing, luminous painting, etc. Recently this concept was also proposed for the development of new optical imaging modalities. At nanoscale, deep red and near-infrared persistent luminescence nanoparticles enable highly sensitive in-vivo optical detection and complete avoidance of tissue autofluorescence [1].
Nanophosphors could also be used to measure thermometry at nanoscale and this appears to be the solution of choice to perform in-vitro and in-vivo temperature readings at cellular scale in real-time. This was the topic of the recent NanoTBTech EU2020 project [2]. Our study highlights that interaction between light and biological tissues is one main challenge to perform robust temperature readings with nanothermometry based on emission spectra. Surface functionalization of these photonic nanoprobes can be adjusted as well as the wavelength of the optical stimulation to favour multiple challenging biomedical applications.
References:
[1]B Viana et al., in “NIR-persistent luminescence nanoparticles for bioimaging, principle and perspectives” Book chapter in Near Infrared-Emitting Nanoparticles for Biomedical Applications, Nature Sringer, 163-197 (2020), D. Jaque et al. ed.
[2] http://nanotbtech.web.ua.pt/
2019
2019
Dr. Eric Anglaret
12.12.2019Spectroscopic studies of dispersion and orientation of carbon nanotubes and graphene in aqueous inks and related nanomaterials
Laboratorie Charles Coulomb, CNRS, Univeristé de Montpellier, Francia
Place: Salón de Grados CicCartuja2
Processing single-walled carbon nanotubes (SWNT) and single-layer graphene (SLG) into thin films or composite nanomaterials are key issues to take advantage of their mechanical, electrical and optical properties. In this talk, we will review our recent results, and primarily optical spectroscopy studies (absorption, Raman and photoluminescence), of the dispersion and orientation of SWNT and SLG in aqueous inks [1-10] as well as the properties of liquid crystals [1-3], thin films [3-5] or composites [6-7] prepared from these inks.
[1] Dispersion and orientation of single walled carbon nanotubes in a chromonic liquid crystal, N. Ould-Moussa et al, Liq. Cryst. 40, 1 (2013)
[2] Liquid crystals of carbon nanotubes and graphene, C. Zakri et al, Phil. Trans. Royal Soc. (2013)
[3] Anisotropic thin films of single wall carbon nanotubes from aligned lyotropic nematic suspensions, C. Zamora-Ledezma et al, Nanoletters 8, 4103 (2008)
[4] Conductivity anisotropy of assembled and oriented carbon nanotubes, C. Zamora-Ledezma et al, Phys. Rev. E 85, 062701(5) (2012)
[5] Morphology and anisotropy of thin conductive inkjet printed lines of single-walled carbon nanotubes, F. Torres-Canas et al, Mat. Res. Exp. 4 (2017)
[6] Orientational order of carbon nanotubes in stretch-aligned photoluminescent composites, C. Zamora-Ledezma, et al, Phys. Rev. B 80, 113407 (2009)
[7] Dispersion and individualization of SWNT in surfactant-free suspensions and composites of hydrosoluble polymers, F. Torres-Canas et al, J. Phys. Chem. C 119, 703 (2015)
[8] Surfactant-free single-layer graphene in water, G. Bepete et al, Nat. Chem. (2016)
[9] Raman Signatures of Single Layer Graphene Dispersed in Degassed Water, “Eau de Graphene”, G. Bepete et al, J. Phys. Chem. C 120, 28204 (2016)
[10] Hydroxide Ions Stabilize Open Carbon Nanotubes in Degassed Water, G. Bepete et al, ACS Nano 12, 8606 (2018)
Dr. Ibraheem Yousef
02.12.2019Applications of infrared microspectroscopy using the synchrotron radiation of Alba light source
MIRAS Beamline Responsible - Experiments Division in ALBA Synchrotron
Place: Salón de Grados CICCARTUJA2
Conferencia dentro del PROGRAMA DE DOCTORADO «CIENCIA Y TECNOLOGÍA DE NUEVOS MATERIALES”
Dr. José Ángel Martín Gago
07.11.2019Nanoscience and Surface Science for studying the Cosmos
Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC)
Place: Salón de Actos de Grados cicCartuja
Evolved stars are a factory of chemical complexity, gas and dust, which contribute to the building blocks of planets and life. However, the dust formation process remains poorly understood. Different laboratory techniques are used to produce analogs of cosmic dust being based the majority of them on uncontrolled combustion or plasma decomposition of molecular precursors in conditions far removed from those in star photospheres.
We have designed and built an unprecedented ultra-high vacuum machine combining gas aggregation sources with in-situ advanced surface science characterization techniques (as STM, XPS or IRAS) and mass spectroscopy [2.] We show that astrochemical problems can be successfully addressed and understood using surface science methodologies. This combination opens the door to the investigation and modelling of processes related to dust particles and its interaction with the gas in different regions of the universe.
Different model systems will be presented. In the first analogues of cosmic dust are analysed to conclude that evolved stars do not form aromatics or fullerenes but aliphatic material made up by bottom-up coalescence[3]. In the second example we propose a new route for the formation of polycyclic aromatic hydrocarbons produced by etching of graphene on the SiC grains in a top-down process[1].
References
[1] Merino P., et al. Nature Communications 5, (2014), 3054
[2] L. Martinez et. Al. Sci Rep. 8 (2018) 7250
[3] L. Martinez, Nat. Astronomy, in press.
Dr. Andries Meijerink
24.10.2019Multi Photon Phosphors
Utrecht University
Place: Salón de Grados cicCartuja2
Lanthanides have transformed the world of lighting in the past 40 years. Presently, almost all artificial light sources rely on emission of light by lanthanide ions. In many luminescent materials, also known as phosphors, one-to-one photon conversion downshifts one high energy photon to one lower energy photon in the desired spectral region. However, recently, there is a significant increase of attention for multi-photon phosphors relying on multi-photon conversion processes, either upconversion or downconversion. Insight in the multi-photon processes is not trivial but is needed to understand the mechanism and improve the efficiency of spectral conversion processes in multi-photon phosphors which is crucial for applications, including solar cells to reduce spectral mismatch losses.
In this presentation a short historical introduction to single- and multi-photon conversion phosphors will be followed by an overview of recent developments of efficient up- and downconversion materials. Next it will be discussed how insight can be obtained in the mechanism and efficiency of up- and downconversion processes. An important aspect involves modelling of energy transfer and ligand quenching. For both up- and downconversion examples will be given on how modelling of luminescence decay curves can provide quantitative insight. A new ligand-quenching model will be presented and applied to understand multi-phonon vibrational quenching in NaYF4:Er,Yb upconversion nanocrystals. Finally a new method will be presented that provides direct proof for downconversion. Correlated emission of photons in photon cutting materials can serve as a fingerprint for the occurrence of downconversion and can even be used to quantify the downconversion efficiency.
Figure 1 – Illustration correlated photon counting to demonstrate two-photon emission using NaLaF4:Pr3+ as model system. (a) Two-photon emission on Pr3+. (b) Schematic set-up for correlated photon counting (c, d) Emission of Pr3+ in blue and red spectral region detected by separate detectors. (e) Correlated photon-counting signal.
Dr. Silvia Vignolini
04.07.2019Colour Engineering: from nature to applications
Department of Chemistry, University of Cambridge
Place: Salón de Grados cicCartuja2
The most brilliant colours in nature are obtained by structuring transparent materials on the scale of the wavelength of visible light. By controlling/designing the dimensions of such nanostructures, it is possible to achieve extremely intense colourations over the entire visible spectrum without using pigments or colorants. Colour obtained through structure, namely structural colour, is widespread in the animal and plant kingdom [1]. Such natural photonic nanostructures are generally synthesised in ambient conditions using a limited range of biopolymers. Given these limitations, an amazing range of optical structures exists: from very ordered photonic structures [2], to partially disordered [3], to completely random ones [4].
In this seminar, I will introduce some striking example of natural photonic structures [2-4] and review our recent advances to fabricate bio-mimetic photonic structures using the same material as nature. Biomimetic with cellulose-based architectures enables us to fabricate novel photonic structures using low cost materials in ambient conditions [6-7]. Importantly, it also allows us to understand the biological processes at work during the growth of these structures in plants.
[1] Kinoshita, S. et al. (2008). Physics of structural colors. Rep. Prog. Phys. 71(7), 076401.
[2] Vignolini, S. et al. (2012). Pointillist structural color in Pollia fruit. PNAS 109, 15712-15716.
[3] Moyroud, E. et al. (2017). Disorder in convergent floral nanostructures enhances signalling to bees. Nature 550, 469.
[4] Burresi M. et al. (2014) Bright-White Beetle Scales Optimise Multiple Scattering of Light. Sci.Rep. 4, 727
[5] Parker R. et al. (2018) The Self-Assembly of Cellulose Nanocrystals: Hierarchical Design of Visual Appearance. Adv Mat 30, 1704477
[6] Parker R. et al. (2016). Hierarchical Self-Assembly of Cellulose Nanocrystals in a Confined Geometry. ACS Nano, 10 (9), 8443–8449
[7] Liang H-L. et al. (2018). Roll-to-roll fabrication of touch-responsive cellulose photonic laminates, Nat Com 9, 4632
Dr. Javier García Martínez
04.04.2019Descubrimiento y Comercialización de una Nueva Familia de Catalizadores
Catedrático de Química Inorgánica de la Universidad de Alicante y Director del Laboratorio de Nanotecnología Molecular (NANOMOL)
Place: Seminario cicCartuja2
El pequeño tamaño de los microporos de las zeolitas dificulta la entrada y salida de las moléculas voluminosas al interior de su estructura; lo que afecta negativamente a la actividad y a la selectividad de un buen número de catalizadores industriales que contienen zeolitas, como por ejemplo, los catalizadores de craqueo catalítico (FCC). Para solucionar esta limitación, hemos desarrollado una nueva estrategia que involucra el tratamiento de zeolitas en disoluciones de surfactantes catiónicos en la presencia de una base. Este proceso post-sintético permite introducir, de forma sencilla y controlable, la mesoporosidad en una gran variedad de zeolitas, a la vez que éstas mantienen sus propiedades más sobresalientes, tales como cristalinidad, estabilidad hidrotermal y actividad catalítica. Este método permite solventar las limitaciones de otros materiales mesoporosos preparados con surfactantes, tales como MCM-41 y otros similares, que carecen precisamente de las propiedades que acabamos de señalar. La presencia de mesoporosidad dentro de la estructura de la zeolita se ha confirmado mediante un amplio conjunto de técnicas de caracterización avanzadas.
Tras el estudio de la actividad y selectividad catalítica de estas zeolitas mesoporosas a escala laboratorio, se procedió a escalar la tecnología produciendo varios kilos de catalizador FCC en una planta piloto. Durante la presentación se mostrarán los resultados catalíticos del craqueo de gasóleo de vacío obtenidos en una unidad de ACE (Advanced Catalytic Evaluation). Las zeolitas mesoporosas que aquí se presentan son una realidad comercial gracias al acuerdo entre la empresa Rive Technology y Grace. Hoy en día estos catalizadores se están utilizando con éxito en varias refinerías de EEUU. En la parte final de la presentación se mostrarán algunos resultados obtenidos en la refinería Alon Big Spring de Texas, EEUU, en el que se confirman los resultados obtenidos a escala piloto. Como era de esperar, la presencia de mesoporosidad en la zeolita incrementa el número de barriles procesados y la producción de gasolina y diésel, a la vez que se reduce notablemente la generación de CO2 y de gases.
Prof. Rishi Raj
18.03.2019Flash Sintering of Ceramics
Universidad de Colorado en Boulder
Place: Salón de Grados cicCartuja2
Flash sintering is a novel densification technology for ceramics, which allows a dramatic reduction of processing time and temperature. It represents a promising sintering route to reduce economic, energetic and environmental costs associated to firing. Moreover, it allows to develop peculiar and out‐of‐equilibrium microstructures. The flash process is complex and unusual, including different simultaneous physical and chemical phenomena and their understanding, explanation and implementation require an interdisciplinary approach from physics, to chemistry and engineering. In spite of the intensive work of several researchers, there is still a wide debate as for the predominant mechanisms responsible for flash sintering process. This talk will include an overview of the original research that led to the discovery of the technique by Prof. Raj, as well as an analysis of the most significant mechanisms proposed for explaining the “flash” event. It will also include future scientific activities and potential technological implementations.
2018
2018
Dr. Jesús Martínez de la Fuente
13.12.2018Hybrid Nanoparticles for Therapy and Diagnosis
Instituto de Ciencia de Materiales de Aragón-CSIC/Universidad de Zaragoza
Place: Salón de Grados cicCartuja2
In the last decades, inorganic nanoparticles have been steadily gaining more attention from scientists from a wide variety of fields such as material science, engineering, physics or chemistry. The very different properties compared to that of the respective bulk, and thus intriguing characteristics of materials in the nanometre scale, have driven nanoscience to be the centre of many basic and applied research topics. Moreover, a wide variety of recently developed methodologies for their surface functionalization provide these materials with very specific properties such as drug delivery and circulating cancer biomarkers detection. In this talk we describe the synthesis and functionalization of magnetic and gold nanoparticles as therapeutic and diagnosis tools against cancer:
-Pseudo-spherical gold nanoparticles derivatized with with fluorescent dyes, cell penetrating peptides and small interfering RNA (siRNA) complementary to the proto-oncogene myc have been tested using a hierarchical approach including three biological systems of increasing complexity: in vitro cultured human cells, in vivo invertebrate (freshwater polyp, Hydra) and in vivo vertebrate (mouse) model. Selection of the most active functionalities was assisted step by step through functional testing adopting this hierarchical strategy. Merging these chemical and biological approaches lead to a siRNA/RGD gold nanoparticle capable of targeting tumor cells in lung cancer xenograft mouse model, resulting in successful and significant c-myc oncogene downregulation followed by tumor growth inhibition and prolonged survival of the animals.
-Gold nanoprisms (NPRs) have been functionalized with PEG, glucose, cell penetrating peptides, antibodies and/or fluorescent dyes, aiming to enhance NPRs stability, cellular uptake and imaging capabilities, respectively. Cellular uptake and impact was assayed by a multiparametric investigation on the impact of surface modified NPRs on mice and human primary and transform cell lines. Under NIR illumination, these nanoprobes can cause apoptosis. Moreover, these nanoparticles have also been used for optoacoustic imaging, as well as for tumoral marker detection using a novel type of thermal ELISA nanobiosensor using a thermosensitive support.
-Magnetic nanoparticles functionalized with DNA molecules and further hybridizing with different length fluorophore-modified DNA have allowed the accurate determination of temperature spatial mapping induced by the application of an alternating magnetic field. Due to the design of these DNAs, different denaturalization temperatures (melting temperature, Tm) could be achieved. The quantification of the denaturalized DNA, and by interpolation onto a Boltzmann fitting model, it has been possible to calculate the local temperature increments at different distances, corresponding to the length of each modified DNA, from the surface of the nanoparticles. The local increments achieved were up to 15ºC, and the rigidity conferred by the double strand DNA allowed to evaluate the temperature at distances up to 5.6 nm from the nanoparticle surface
Dr. P. Brault
08.11.2018Plasma sputtering synthesis of nanocatalyst for fuel cells: Experiments and molecular dynamics simulations
CNRS-Université d’Orléans
Place: Salón de Grados cicCartuja2
Hydrogen powered fuel cells are expected be a relevant solution for green and sustainable energy delivery. Major breakthroughs remain to be achieved. One of them is to lower the noble metal content used as catalysts in the fuel cell electrodes for electrochemical conversion of H2 and O2 from air into electricity, heat and water.
Plasma sputtering deposition of supported nanocatalysts has been demonstrated to improve electrode efficiency of low temperature proton exchange membrane fuel cells. Indeed, sputtering can act as an atom source with a controlled energy distribution, which, in turn, enables to control the nanocatalyst growth on the porous carbon electrode with a controlled in-depth profile. This allow to drastically reduce the noble metal content up to a factor 100. Another way is to alloy the noble metal catalyst (here Pt) with a common metal (Fe, Ni, Mo, …) and also with gold. The latter being not a catalyst but is expected to prevent nanocatalyst sintering during fuel cell operation. Very recently, direct growth of Pt alloy nanocatalyst in the plasma phase have been carried out using gas condensation source leading to well defined and narrow nanocluster size distributions.
As the nanoparticle growth by sputtering methods is atomic by nature, simulations at the molecular level are expected to be relevant for understanding basic mechanisms of this deposition method. Indeed, molecular dynamics (MD) as being able to exactly calculating the trajectory of atomic systems is a suitable method for addressing this topic, especially in the context of plasma sputtering. Very recently, it has been shown that MD simulations allowed confirming and predicting the morphology and structure of Pt nanocatalysts as well as for PtxPdyAuz and PtxNiyAuz. Direct growth in the plasma phase mimicking the gas condensation source is also studied. Initial conditions of MD simulations are selected for matching experimental chemical and physical methods. Radial distribution functions and X-Ray Diffraction pattern are systematically computed for enabling direct comparison with experiments.
Prof. Thomas Tsakalakos
18.10.2018Electric Field Manipulation of Matter via Synchrotron Radiation
Rutgers University
Place: Salón de Grados cicCartuja2
Flash Sintering (FS), a relatively new method, densifies ceramic powders, in seconds, at very low temperatures. A non-equilibrium rise in current, under applied electric field, is used to densify matter. EDXRD Temperature Calibration utilizes white energy dispersive x-ray diffraction (EDXRD) from a synchrotron source to track the lattice expansion of the ceramic during FS. In this presentation, studies on the following materials will be discussed: ZnO, TiO2, CeO2 and BiFeO3 oxides and B4C , TiB2 ZrB2 and BN nonoxides. This In-Situ investigation analysis of mechanisms at the onset of FS, the cause of enhanced sintering kinetics during FS and applied temperatures for each theory will be presented. New ways of performing FS experiments on ZnO by ramping the current linearly and by AC power supply, microstructural inhomogeneity, grain growth, and other physical properties will be also shown. FS of BiFeO3 is a homogeneous process at exceptionally low temperatures (350 ºC < Tc) will be described as well as the excellent dielectric properties that are discovered.
Dr. A. West
24.05.2018Solid state chemistry of oxides: some properties and applications
University of Sheffield, Reino Unido
Place: Salón de Grados cicCartuja2
The talk will focus on the common occurrence of a variable metal-oxygen ratio in many inorganic oxides and its consequences for a diverse range of electrical properties and applications. Comparisons will be made between the occurrence of non–stoichiometry in many oxides and the exact stoichiometry of molecular compounds. In some cases, oxygen in oxides is more than just an inert O2- packing ion in a crystal structure, but can take part in redox processes similar to transition metal cations. Topics covered in the talk should include: lithium battery cathodes, black rutile, p-n transitions in oxide ceramics and memristive switching phenomena, to illustrate the underlying physical processes responsible for the diverse range of properties.
Dr. D. Poelman
26.04.2018Stretching the wave: the quest for long-wavelength phosphors for displays, lighting and medical imaging
Ghent University, Bélgica
Place: Salón de Grados cicCartuja2
Most of today’s high efficiency white LEDs are based on a blue-emitting LED chip, combined with one or more phosphor materials. In order to achieve the high colour quality necessary for home lighting, new phosphors should be developed having suitable emission in the red part of the spectrum, thus decreasing the CCT (correlated colour temperature) and increasing the CRI (colour rendering index) of the white light. We will discuss the requirements for this class of materials for both displays and lighting: they have to combine a sufficiently long dominant wavelength with a minimal fraction of the emission beyond 650 nm, where the eye sensitivity is low. Materials include both Eu-doped and Mn-doped compounds. Using Eu, the challenge is to stretch the emission to a sufficiently long wavelength, while using Mn, efforts are needed to tune the emission to a sufficiently short wavelength.
For some applications, such as in vivo medical imaging, even longer wavelengths are needed, typically in the range between 650 and 950 nm, in the so-called first tissue transparency window. We will evaluate the possible use of Cr3+ or Mn4+ as dopants for this application. In addition, we will try to turn these phosphors into persistent luminescent emitters, showing emission up to hours after the excitation has ended. Such long afterglow materials open op exciting possibilities for medical imaging, avoiding many of the drawbacks of commonly used imaging methods.
Dr. Raúl A. Rica Alarcón
25.04.2018Levitación de nanopartículas en alto vacío mediante trampas ópticas y de iones
Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada
Place: Seminario cicCartuja2
La levitación de nanopartículas en alto vacío ha emergido como un sistema singular que permite explorar distintas fronteras de la física, en particular en física estadística y la aplicabilidad de la mecánica cuántica en la mesoescala [1-4]. En este seminario, daré una introducción a la rica fenomenología observada en este tipo de sistemas, y describiré nuestros progresos en la implementación de distintos tipos de levitación, tales como la levitación óptica y mediante el uso de trampas de iones. Primero presentaré algunos resultados que demuestran un control muy preciso sobre la dinámica no lineal de una nanopartícula atrapada ópticamente, así como de la dinámica estocástica bi-estable que presenta el sistema [5]; a continuación introduciré el uso de trampas de iones como alternativa a las ópticas, permitiendo el atrapamiento estable de nanopartículas con grados internos de libertad tales como nanodiamantes con defectos nitrógeno-vacante [6,7]. Finalmente, veremos cómo es posible controlar la carga de la nanopartícula creando un plasma cerca de la trampa, y discutiremos algunas de las posibilidades que ofrece esta nueva configuración.
Fig.1 Imagen de una única nanopartícula atrapada mediante una trampa de Paul y situada en el foco de un haz láser focalizado mediante un objetivo.
La visualización es posible gracias al scattering emitido por la partícula tras su interacción con el haz.
[1] J. Gieseler et al. Phys. Rev. Lett. 109, 103603 (2012)
[2] J. Gieseler et al. Nature Nano. 9, 358-364 (2014)
[3] V. Jain et al. Phys. Rev. Lett. 116, 243601 (2016)
[4] N. Kiesel et al. PNAS 110, 14180-14185 (2013)
[5] F. Ricci et al. Nature Comms. 8, 15141 (2017)
[6] I. Alda et al. Appl. Phys. Lett. 109, 163105 (2016)
[7] G.P. Conangla et al. preprint arXiv:1803.05527 (2018)
Dr. S. Stranks
13.04.2018Halide Perovskites for Photovoltaic and Light-Emission Applications
Cavendish Laboratory, Cambridge
Place: Salón de Grados cicCartuja2
Metal halide perovskites are exotic hybrid crystalline materials developed out of curiosity. Unexpectedly, solar cells and light-emitting diodes (LEDs) incorporating these perovskites are rapidly emerging as serious contenders to rival the leading technologies. Photovoltaic power conversion efficiencies have jumped from 3% to over 22% in just seven years of academic research, and we are witnessing a similarly astonishing pace in LEDs. Here, I will give an overview of some of our key photophysical findings to advance understanding of the optoelectronic behaviour of the perovskite materials and operation of the state-of-the-art devices. I will cover topics including charge carrier diffusion and recombination, as well as ion migration and its potential impact on device performance. I will identify avenues towards eliminating losses by focusing on the relationships between micro- and nano-scale optoelectronic, chemical and structural properties of these materials as neat films and in operating devices. Understanding these properties is key to further development of the field and to bringing the perovskite technology to commercialisation.
Dr. Markus Antonietti
15.03.2018Nanostructured N-doped Carbon and Carbon nitride materials: Enzyme-like Heterogeneous Catalysts?
Max Planck Institute of Colloids and Interfaces, Research Campus Golm, D-14424 Potsdam, Alemania
Place: Salón de Grados cicCartuja2
Carbon nanoparticles and nanostructures which are doped with the element nitrogen (“N-doped”) have special properties, among them high oxidation resistance and high electronic conductivity. These carbon materials can be made by thermal condensation
Of special monomers, among them for instance nucleobases
About 10 years ago, it was found that such carbons are very powerful electrocatalysts, even when metal-free, an can catalyse a number of “world reactions”, such as the reduction of oxygen or the conversion of soda water into formic acid. In addition, the materials are also very favourable supports for metallic nanocatalysts, which is attributed to a bulk heterojunction effect.
When going to even high nitrogen contents, Carbon nitrides or polyheptazinimides are obtained, and the resulting semiconductors can promote artificial photosynthesis, including water splitting and CO2 conversion. I will present a number of completely new chemical reactions only possible with such colloids which indicate how such clusters could have contributed to the existence of chemical diversity, potentially also on a prebiotic earth-like planet.
References:
1) Polymeric Graphitic Carbon Nitride as a Heterogeneous Organocatalyst: From Photochemistry to Multipurpose Catalysis to Sustainable Chemistry; Wang, Yong; Wang, Xinchen; Antonietti, Markus ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 51 68-89 (2012)
2) Efficient Metal-Free Oxygen Reduction in Alkaline Medium on High-Surface-Area Mesoporous Nitrogen-Doped Carbons Made from Ionic Liquids and Nucleobases: Yang, Wen; Fellinger, Tim-Patrick; Antonietti, Markus, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 133 206-209 (2011)
Dr. A. Bogaerts
16.02.2018Plasma catalysis for CO2 conversion: A better understanding of the underlying mechanisms
Research group PLASMANT, University of Antwerp, Department of Chemistry, Belgium
Place: Salón de Grados cicCartuja2
Plasma catalysis is gaining increasing interest for CO2 conversion. To improve this application in terms of conversion, energy efficiency and product formation, a good insight in the underlying mechanisms is desirable. We try to obtain this by computer modelling and experiments.
Experimentally, we study two types of plasma reactors, i.e., dielectric barrier discharges (DBDs) in which we insert packing materials to investigate plasma catalysis, as well as a gliding arc (GA) discharge. In this talk, I will show some results for both, illustrating the superior energy efficiency of a GA reactor.
In addition, we also simulate the plasma chemistry as well as the optimum reactor design, in the three types of plasma reactors most commonly used for CO2 conversion, i.e., DBDs, GA discharges and microwave (MW) plasmas. For the plasma reactor design, we use 2D or 3D computational fluid dynamics modelling. For the plasma chemistry, we make use of zero-dimensional chemical kinetics modeling, which solves continuity equations for the various plasma species, based on production and loss terms, as defined by the chemical reactions. Typically, up to 100 different species are considered, which react among each other in up to 1000 different chemical reactions.
When studying the plasma chemistry in pure CO2, we focus especially on the the role of vibrationally excited CO2 levels, which are the key species for enhanced energy efficiency of the CO2 conversion. Our model reveals the relative importance of various processes, responsible for the CO2 conversion, and this is linked to the energy efficiency in the various types of plasma reactors.
We have also studied the plasma chemistry in CO2/CH4 and in CO2/H2O mixtures, to produce value-added chemicals. The main products formed are a mixture of H2 and CO, or syngas, with a tuneable H2/CO ratio depending on the gas mixing ratio. The production of oxygenated compounds, such as methanol, formaldehyde, etc, is very limited, showing the need for combining with a catalyst. A detailed chemical kinetics analysis allows to elucidate the different pathways leading to the observed results, and to propose solutions on how to further improve the formation of value-added products.
Likewise, we also studied the plasma chemistry in a CO2/N2 mixture, to investigate the effect of this important impurity in effluent gases on the CO2 conversion, energy efficiency and product formation. Several harmful compounds, i.e., N2O and NOx compounds, are produced in the range of several 100 ppm. The reaction pathways for the formation of these compounds are again explained based on a kinetic analysis, which allows proposing solutions on how to prevent the formation of these harmful compounds.
Finally, we also study plasma-catalyst interactions, by experiments, atomic scale simulations (density functional theory), as well as fluid and particle-in-cell – Monte Carlo simulations. The latter is used to investigate whether plasma can be formed inside catalyst pores.
Dr. B. Rauschenbach
18.01.2018Nanostructures – Preparation and Applications
Leibniz-Institut für Oberflächmodifizierung
Place: Salón de grados cicCartuja2
Nanostructures with a three dimensional tailored shapes are promising candidates for a variety of applications. Sputter technology, oblique angle deposition and glancing angle deposition are sophisticated methods to create nanostructures with custom-made structure geometries. Selected results of these three methods to prepare nano- and micro-structures are presented. (1.) Low-energy ion beam sputtering, i.e. the removal of atoms from a surface due to the impact of energetic ions or atoms, is an inherent part of numerous surface processing techniques. Two prominent examples are the spontaneous formation of well-ordered ripple or dot pattern and the realization of experimental conditions where surface relaxation dominates and smooth surfaces are emerging. Both special cases are of high interest for many potential applications in nanotechnology. (2.) Combining ion sputter deposition or electron beam evaporation and oblique angle deposition represents an elegant and powerful technique to sculpture manifold surface morphologies on the nanometer scale. Besides different examples of films prepared by oblique deposition a model describing the growth of nanostructures for the full angle of incidence range (0° - 90°) is proposed. Predictions of this model for tilt angles and porosities are shown and compared to an off-lattice computer simulation as well as to deposited films of different materials. (3.) A constant or periodically interrupted substrate rotation during deposition is used to tailor structures like chevrons, posts, circular and quadratic spirals or zig-zags. The growth of these nanostructures on nonpatterned substrates, regularly arranged Si nanostructures and the growth conditions are discussed. Regular arrays of nanostructures are grown on several substrates by patterning with Au dots using selfassembled mono- and double layers of polystyrene nano-spheres as evaporation mask or electron beam lithography. Finally, examples are given for the applications of sculptured thin films in the field of chemical and biosensors.
2017
2017
Prof. Mathieu Allix
15.09.2017Tailoring crystallization in oxide glasses: Application to transparent polycrystalline ceramics and nanostructured glass-ceramics
Conditions Extrêmes et Matériaux: Haute Température et Irradiation (CEMHTI); CNRS - Centre national de la recherche scientifique, Orléans (France)
Place: Salón de grados cicCartuja2
Crystallization from glass can be a powerful process to elaborate innovating transparent materials for optical and photonic applications if nucleation and crystal growth steps can be precisely controlled. This talk will focus on two main applications: transparent polycrystalline ceramics elaborated by full and congruent crystallization from glass and nanostructured glass-ceramics designed from nanoscale phase separated glasses.
Transparent polycrystalline ceramics elaborated by full crystallization from glass
Transparent ceramics are an emerging class of optical materials competing with single crystal technology for a broad range of applications. Ceramics offer several advantages, particularly in the fabrication of complex shapes and large-scale industrial production, and enable great and homogenous doping of optically active ions. However, up to date, only a limited number of cubic or nanocrystalline transparent polycrystalline ceramics requiring complex and expensive synthetic approaches has been reported. Our recent work shows the possibility to obtain new transparent ceramics by full and congruent crystallization from glass. This is demonstrated in the case of several new compositions, such as BaAl4O7, Sr3Al2O6 and Sr3Ga2O6, all showing high transparency in the visible and infra-red ranges. Lately, we have focused our work on large scale and highly transparent strontium aluminosilicate compositions. A crystallographic study coupled to NMR experiments and DFT calculations of the birefringence evidences the role of structural disorder (Al/Si substitution and presence of vacancies on strontium sites) to explain the optical isotropy observed in these hexagonal materials. These results propose an innovative concept, the addition of a controlled structural disorder within crystalline structures, in order to lower the birefringence and to elaborate new transparent ceramics.
Transparent nanostructured glass and glass-ceramics
New nanostructured gallogermanate- and gallosilicate-based glass materials exhibiting high transparency in the visible range have been fabricated by conventional melt-quenching. These materials can accommodate wide oxide compositions and present nanoscale phase separation. The size of the nanostructuring can be tailored depending on the nominal composition. A single heat treatment then allows selective crystallization of the phase separated glass, resulting in glass-ceramic materials exhibiting nanostructures and transparency similar to the parent glass [8, 9]. The wide possibilities of designing new nanostructured glass-ceramics with tunable optical properties will be illustrated in the case of a highly transparent ZnGa2O4 glass-ceramic exhibiting 50 wt% of nanocrystals with homogeneous and tunable sizes. High resolution scanning transmission electron microscopy analysis coupled with in situ high temperature X-ray diffraction and optical measurements led to a detailed description of the crystallization process. Remarkably, red long-lasting luminescence arising from the entire sample volume is observed in this Cr3+ doped material, opening the route to a wider range of performing applications for this famous zinc gallate persistent phosphor [10, 11].
1. M.Allix et al., Advanced Materials, 24 5570-5575 (2012). 2. International patent deposited 1/12/2011, published 6/6/2013. 3. G.Patton et al., PCCP, 16 24824 (2014). 4. M.Boyer et al., J. Mater. Chem. C, 4 3238-3247 (2016). 5. S.Alahraché et al, Chemistry of Materials, 25 4017-4024 (2013). 6. M.Boyer et al. Cryst. Growth Des., 16 386-395 (2016). 7. K.Al Saghir et al., Chemistry of Materials, 27 508-514 (2015). 8. International patent deposited 28/02/2014, published 4/9/2014,. 9. S.Chenu et al. Advanced Optical Materials, 2 364 (2014). 10. S. Chenu et al. J. Mater. Chem. C, 2 10002-10010 (2014). 11. M.Allix et al. Chemistry of Materials, 25 1600–1606 (2013).
Prof. Derek C. Sinclair
16.06.2017The influence of non-stoichiometry and chemical doping on the electrical properties of Na1/2Bi1/2TiO3 ceramics
Departamento de Ciencia de Materiales e Ingeniería University of Sheffield, UK
Place: Salón de grados cicCartuja2
ABO3-type perovskite oxides exhibit a diverse range of useful functional properties from ferroelectric BaTiO3 materials for dielectric applications in multilayer ceramic capacitors to solid electrolytes and mixed oxide-ion, electronic conducting electrodes for solid oxide fuel cells. The ferroelectric perovskite Na1/2Bi1/2TiO3 (NBT) is known to exhibit interesting and diverse structure-composition-property relationships. A combination of A-site (Na, Bi) disorder, Bi- and Ti- displacements and in-phase and out-of-phase octahedral tilting ensures the crystal chemistry and polymorphism of NBT remain a challenging subject, especially below ca. 520 oC where distortions from the ideal ‘cubic’ cell are reported to occur. Furthermore, the electrical conductivity of undoped NBT materials are known to be critically dependent on low levels of A-site non-stoichiometry.
Here we review the structure-composition-property relationships of NBT materials based on a combination of A-site non-stoichiometry and chemical doping. We use results to show nominally Na-rich or Bi-deficient NBT ceramics to be excellent oxide-ion conductors whereas nominally Na-deficient or Bi-excess NBT ceramics are electrically insulating but retain. This shows undoped NBT ceramics to be mixed ion-electron conducting materials.
Finally, we discuss the differences in the defect chemistry of NBT compared to conventional titanate perovskites, such as (Ba,Sr)TiO3.
References
[1] E. Aksel, J.S. Forrester, J.L. Jones, P.A. Thomas, K. Page, and M.R. Suchomel, Appl. Phys. Lett., 98, 152901 (2011);
[2] I. Levin and I.M. Reaney, Adv. Funct. Mater., 22, 3445–3452 (2012);
[3] Y. Hiruma, H. Nagata, and T. Takenaka, J. Appl. Phys., 105, 084112 (2009);
[4] M. Li, M.J. Pietrowski, R.A. De Souza, H. Zhang, I.M. Reaney, S.N. Cook, J.A. Kilner, and D.C. Sinclair, Nat. Mater., 13, 31–35 (2014);
[5] M. Li, H. Zhang, S.N. Cook, L. Li, J.A. Kilner, I.M. Reaney, and D.C. Sinclair, Chem. Mater., 27, 629–634 (2015);
[6] M. Li, L. Li, J. Zang, and D.C. Sinclair, Appl. Phys. Lett., 106, 102904 (2015).
Prof. Luisa De Cola
18.05.2017Luminescent assemblies, imaging and cellular lasing
Institute de Science et d'Ingénierie Supramoléculaires (I.S.I.S.), Université de Strasbourg and KIT, Germany
Place: Salón de grados cicCartuja2
Luminescent molecules that can undergo self-assembly are of great interest for the development of new materials, sensors, biolabels…. The talk will illustrate some of the recent results on soft structures based on metal complexes able to aggregate in fibers, gels and soft mechanochromic materials [1]. The use of platinum complexes as building block for luminescent reversible piezochromic and mechanochromic materials, down to the nanoscale, will be illustrated [2]. The emission of the compounds can be tuned by an appropriate choice of the coordinated ligands as well as of their aggregation in different structures. The formation of soft assemblies allows the tuning of the emission color, by pressure and temperature leading to a new class of materials possessing reversible properties. We demonstrate how even small changes in molecular design can completely inhibit or enhance the formation of organized supramolecular architectures, leading to a deep understanding of the key factor affecting the whole self-assembly process.
The monitoring of the different emission properties, used as fingerprint for each of the assembled species, allowed an unprecedented real-time visualization of the evolving self-assemblies [3].
In the final part of the talk a new concept, mirrorless cellular lasing, i.e. to generation of strong laser action from stained biological cells and, importantly, in absence of any external resonators is described. Interestingly, such phenomenon is connected to the biological components that constitute the structure of the cells involved in laser generation [4].
References
[1] C. A. Strassert, L. De Cola et al. Angew. Chem. Int. Ed., 2011, 50, 946; M. Mauro, L. De Cola et al. Chem. Commun. 2014, 50, 7269
[2] D. Genovese, L. De Cola et al. Adv. Funct. Mater., 2016, 26, 5271–5278
[3] A. Aliprandi, M. Mauro, L. De Cola Nature Chemistry , 2016, 8, 10-15
[4] D. Genovese, V. Barna, L. De Cola submitted
Kostya (Ken) Ostrikov
20.04.2017Plasma-synergistic effects: catalysing cross-disciplinary collaborations
Queensland University of Technology (QUT) and CSIRO, QUT-CSIRO Joint Sustainable Processes and Devices Laboratory. Australia
Place: Salón de Grados cicCartuja2
This presentation will introduce the key features of low-temperature plasmas that make them a versatile tool in materials science and engineering and other areas such as chemical engineering and health sciences. Particular attention will be paid on synergistic effects of plasmas with common materials and processing methods and what difference it makes in diverse applications, with particular focus where nanoscale features of materials play a role. These localized interactions have opened opportunities for fundamental research and applications in the plasma nanoscience field.
The focused “what can plasma do for you” examples will be used to stimulate collaborative efforts even between researchers normally working in completely disparate fields.
Dr. Cuong Pham-Huu
16.03.2017Materials for catalysis: challenges and opportunities
Institute of Chemistry and Processes for Energy, Environment and Health (ICPEES, UMR 7515) CNRS and University of Strasbourg, France
Place: Salón de Grados CicCartuja2
New catalytic materials have been extensively developed since the last decades for application in several research fields including sensors, drug delivery, light-weight high mechanical strength composites and catalysis. In this presentation, we will discuss about last developments on the use of (i) confinement effect in 1D carbon channel, (ii) nanostructuration of 2D carbon via catalytic patterning along with the uncovering of the patterning mechanism by operand transmission electron microscopy, and (iii) development of new bio-sourced mesoporous carbon doped with nitrogen as an active and selective metal-free catalyst for oxidation process. The first example reports on the use of confinement effect to modify and selectively cast, metal oxides, inside 1D carbon material for applications in the field of drug delivery, biological imaging and catalysis. In the second example, catalysis has been used to perform nanopatterning of few-layer graphene, leading to the generation of higher reactive edge sites, for the subsequence anchorage of metal oxide nanoparticles with improved sintering resistance for application in the field of sensor and liquid-phase reactions. The direct analysis of the process by operando TEM at ambient conditions allows one to uncover the different mechanisms operated during the patterning process for future optimization step. The last example focus on the synthesis of nitrogen-doped mesoporous carbon, issued from bio-sourced raw materials, decorated silicon carbide as metal-free catalyst for the selective oxidation of trace amount of H2S into elemental sulfur with improved activity and stability. The presentation will end-up with some future perspectives about the use of carbon-based metal-free catalysts in some relevant catalytic processes as well as the role of operando TEM investigation for unraveling catalytic mechanisms.
Prof. Dr. Anders Hagfeld
16.02.2017The Versatility of Mesoscopic Solar Cells
Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
Place: Salón de Grados CicCartuja2
In our work on solid-state dye-sensitized solar cells (ssDSSC) we have recently [1] shown that copper phenanthroline complexes can act as an efficient hole transporting material. We prepared ssDSCs with the organic dye LEG4 and copper(I/II)-phenantroline as redox system and achieved power conversion efficiencies of more than 11%. Our follow up work on electron transfer studies and device optimization will be presented at the meeting.
In our work on perovskite solar cells (PSC) we have achieved efficiencies above 20% with a mixed composition of iodide/bromide and methyl ammonium/formamidinium [2]. For cells larger than 1 cm2 we recently certified a record efficiency of 19.6% [3], replacing the anti-solvent step in the perovskite film formation with a vacuum flash treatment. With the use of SnO2 compact underlayers as electron acceptor contacts we have constructed planar perovskite solar cells with a hysteresis free efficiency above 20% [4]. Recently, we have taken the cation mixing of the perovskite film further by including the Cs+ in a so-called ‘triple cation’ composition, i.e. Cs/FA/Ma. Larger grains grown in a monolithic manner are observed and for example reproducibility and device stability are improved [5]. At the meeting we will discuss our follow up works [6] and present our champion data; up to 22% efficiency with an external electroluminescence of 4%, and an outstanding open-circuit voltage of 1.24 V at a band gap of 1.63 eV entailing one of the smallest loss-in-potential of 0.39 V ever measured for any solar cell material. Furthermore, we will report a breakthrough in stability at 85 oC for 500 h under full solar illumination and maximum power point tracking (during which 95% of the initial performance was retained).
References
[1] Freitag et al., Energy & Envir. Sci., DOI: 10.1039/C5EE1204J
[2] Bi et al., Science Advance, DOI: 10.1126/sciadv.1501170
[3] X. Li et al., Science, DOI:10.1126/science.aaf8060
[4] Correa et al., Energy & Envir. Sci., DOI:10.1039/C5EE02608C
[5] M. Saliba et al., Energy & Envir. Sci., 2016, DOI: 10.1039/C5EE03874J
[6] M. Saliba et al., Science 10.1126/science.aah5557 (2016)
2016
2016
Prof. Dr. Oliver Gröning
18.11.2016On-surface synthesis and properties characterization of novel low-dimensional materials
Empa, Swiss Federal Laboratories for Materials Testing and Research
Place: Salón de Grados CicCartuja2
In recent years on-surface chemical synthesis routes have succeeded in producing atomically precise nanostructures, whose synthesis cannot be achieved by standard wet chemical processes. This circumstance is due to a great extend to the usually insoluble nature of the products. In this respect, particular attention has been devoted to graphene derived carbon nanostructures such as graphene nanoribbons (GNR) and regular 2D carbon networks[1,2]. In our presentation we will review the recent developments in the field of on-surface chemical synthesis with a particular emphasis on the importance UHV-analytical and computational tools in understanding the physicochemical processes involved in the synthesis and in assessing the electronic properties of the produced nanostructures. The first part of the presentation will mainly touch the role of specific molecular precursors for the synthesis of graphene derived 2D and 1D nanostructures. We will discuss the electronic properties of these novel nanomaterials and their prospects to be used in future electronic devices.
In the second part the question, how the chemical synthesis can be guided by specific atomic surface structures will be addressed. In this context, we will turn our attention to the PdGa compound, which has been found to combine high selectivity and activity in acetylene semi-hydrogenation [3]. We will discuss the non-trivial atomic structure of the (111) and (-1-1-1) PdGa surface, which differ significantly in the local structure of the top most Pd atoms and therefore are model surfaces to study active site isolation and ensemble effects on catalyst selectivity [4]. We will then explore the possibilities of chiral selective adsorption and synthesis on these surfaces made possible by the intrinsic chiral nature of the P213 space group PdGa belongs to [5]. We show that the intrinsically chiral surfaces of PdGa can induce 99% chiral adsorption selectivity of prochiral 9-Ethynylphenantrene (9-EP) at room temperature. Similarly high chiral selectivity can be achieved in producing prochiral 9-EP trimers, which shows the potential of achieving highly asymmetric chemical synthesis on a high temperature stable metallic catalyst.
[1] J. Cai, et al.,Nature 466, 470 (2010)
[2] M. Bieri, et al., JACS 132 16669, (2010)
[3] M. Armbrüster, M. Kovnir, M. Behrens, D. Teschner, Y Grin, and R. Schlögl, JACS 132, 14745 (2010)
Prof. Dr. Bettina V. Lotsch
13.09.20162D or not 2D? Two-dimensional nanostructures for sensing and energy conversion
Max Planck Institute for Solid State Research, Stuttgart, Germany
Place: Salón de Grados del CicCartuja2
A central paradigm of nanochemistry is the rational synthesis, manipulation and assembly of nanoscale building blocks into hierarchical structures with tailor-made properties. Owing to their chemical diversity and wide scope of physical properties, 2D nanostructures lend themselves particularly well as versatile building blocks in miniaturized devices and for the directed self-assembly of hybrid superlattices with engineered functionalities. Our recent progress in the synthesis and integration of novel 2D bulk and nanosheet materials will be reviewed and their emerging applications in photonic sensing, solar energy conversion and as solid electrolytes will be discussed.
Prof. Dr. Claes-Göran Granqvist
21.04.2016Electrochromics and thermochromics: Towards a new paradigm for energy efficient buildings
Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Uppsala, Sweden
Place: Salón de Actos del CicCartuja | 12.00 h
About forty per cent of the World’s primary energy is used for heating, cooling, lighting and ventilating buildings. New nanotechnologies are able to decrease the use of energy significantly at the same time as the comfort and amenities of the building are improved. This talk surveys a number of options, mostly based on work in the speaker’s laboratory. Foci lie on windows and glass facades with electrochromic and thermochromic properties. Functional principles, thin film preparation and properties, new plasmonic nanomaterials, and technological prospects are discussed.
Prof. Dr. Markus Niederberger
18.02.2016Nanoparticles as Building Blocks for Multicomponent Materials and Films
Laboratory for Multifunctional Materials, ETH Zurich, Switzerland
Place: Salón de Actos del CicCartuja | 11.00 h
Nanostructures including nanoparticles, nanowires and nanosheets are the ideal building blocks for the bottom-up fabrication of functional materials. They offer an immense variety of interesting properties, which not only depend on the composition, but also on the crystal structure, the particle size and shape and on the surface chemistry. Accordingly, potential synthesis routes have to provide full control over all these parameters. In addition, for most applications the nanoparticles have to be assembled and processed into useful geometries, including 2-dimensional arrangements like films or 3-dimensional bodies like composites, foams or aerogels. The talk will give a short introduction to the synthesis of metal oxide nanoparticles by nonaqueous sol-gel chemistry, and it will briefly discuss the underlying chemical mechanisms leading to nanoparticle formation. Moreover, several examples will be shown, how the nanoparticles can be processed into films and nanostructured bulk materials for specific applications in gas sensing, dye adsorption, or energy storage and conversion.
2015
2015
Prof. Javier Pérez-Ramírez
12.11.2015Design of Hierarchically Organized Zeolite Catalysts
Institute of Chemical and Bioengineering ETH Zurich, Switzerland
Place: Salón de Actos del CABIMER | 12.00 h
This lecture overviews recent progress towards the design of hierarchically-structured zeolites for application in catalysis. I will illustrate the benefits attained due to the improved access and molecular transport in zeolite crystals with auxiliary pore networks, emphasizing recent advances that contribute to the integral design of these materials for established and new catalytic processes. This includes preparative aspects by strategic post-synthetic modifications, the development of advanced characterization tools to assess descriptors, and the transition from laboratory practices with powders to the multi-ton scale up and structuring of the hierarchical zeolites into technical form. Current needs and future directions will be discussed.
1. J. Pérez-Ramírez, Nature Chem. 2012, 4, 250.
2. S. Mitchell, N.-L. Michels, K. Kunze, J. Pérez-Ramírez, Nat. Chem. 2012, 4, 825.
3. S. Mitchell, N.-L. Michels, J. Pérez-Ramírez, Chem. Soc. Rev. 2013, 42, 6094.
4. M. Milina, S. Mitchell, N.-L. Michels, J. Kenvin, J. Pérez-Ramírez, J. Catal. 2013, 308, 398.
5. L. Gueudré, M. Milina, S. Mitchell, J. Pérez-Ramírez, Adv. Funct. Mater. 2014, 24, 209.
6. T. C. Keller, S. Isabettini, D. Verboekend, E. G. Rodrigues, J. Pérez-Ramírez, Chem. Sci. 2014, 5, 677.
7. M. Milina, S. Mitchell, P. Crivelli, D. Cooke, J. Pérez-Ramírez, Nat. Commun. 2014, 5:3922, DOI: 10.1038/ncomms4922
8. N.-L. Michels, S. Mitchell, J. Pérez-Ramírez, ACS Catal. 2014, 4, 2409.
9. M. Milina, S. Mitchell, P. Crivelli, D. Cooke, J. Pérez-Ramírez, Angew. Chem. Int. Ed. 2015, 54, 1591.
10. M. Morales, P.Y. Dapsens, I. Giovinazzo, J. Witte, C. Mondelli, S. Papadokonstantakis, K. Hungerbühler, J. Pérez-Ramírez, Energy Environ. Sci. 2015, 8, 558
Dr. Peter Strasser
24.09.2015Sunlight, free electrons and molecular bonds: Design of catalysts and reactive interfaces for energy storage and conversion
The Electrochemical Energy, Catalysis, and Materials Science Laboratory. Departament of Chemistry, Chemical Engineering Division. Technical University Berlin. Alemania
Place: Salón de Actos del CicCartuja | 12.00 h
Catalytic materials are key components of (photo)electrochemical devices and technologies for storing and converting renewable electricity. Their successful development and optimization requires insight into the relation between the atomic-scale chemical structure of the electrified interface and its catalytic activity, selectivity, and stability.
In this talk, we will highlight some of our recent work on the fundamental understanding of electrocatalytic nanomaterials and their liquid-solid interface at the atomic-scale. We will outline the preparation, characterization, and catalytic performance of a number of different nanomaterials and solar fuel reactions and discuss relations between structure, activity, selectivity, and stability. Topics will touch upon the acid and alkaline oxygen electrode(1-17) and the electroreduction of CO2(18-21).
1. P. Strasser, Science, 2015, 349, 379-380.
2. B. H. Han, C. E. Carlton, A. Kongkanand, R. S. Kukreja, B. R. Theobald, L. Gan, R. O'Malley, P. Strasser, F. T. Wagner and Y. Shao-Horn, Energy Environ. Sci., 2015, 8, 258-266.
3. N. R. Sahraie, J. P. Paraknowitsch, C. Göbel, A. Thomas and P. Strasser, J. Am. Chem. Soc., 2014, 136, 14486-14497.
4. L. Gan, C. Cui, M. Heggen, F. Dionigi, S. Rudi and P. Strasser, Science, 2014, 346, 1502-1506.
5. L. Gan, M. Heggen, R. O’Malley, B. Theobald and P. Strasser, Nano Lett., 2013, 13, 1131-1138.
6. C. Cui, L. Gan, M. Heggen, S. Rudi and P. Strasser, Nature Mat., 2013, 12, 765.
7. P. Strasser, S. Koh, T. Anniyev, J. Greeley, K. More, C. F. Yu, Z. C. Liu, S. Kaya, D. Nordlund, H. Ogasawara, M. F. Toney and A. Nilsson, Nature Chem., 2010, 2, 454-460.
8. P. Strasser, Rev. Chem. Eng., 2009, 25, 255-295.
9. R. Srivastava, P. Mani, N. Hahn and P. Strasser, Angewandte Chemie International Edition, 2007, 46, 8988-8991.
10. S. Koh and P. Strasser, J. Am. Chem. Soc., 2007, 129, 12624-12625.
11. H.-S. Oh, H. N. Nong and P. Strasser, Adv. Funct. Mater., 2015, 25, 1074-1081.
12. H. S. Oh, H. N. Nong, T. Reier, M. Gliech and P. Strasser, Chem. Sci., 2015, 6, 3321-3328.
13. H. N. Nong, H. S. Oh, T. Reier, E. Willinger, M. G. Willinger, V. Petkov, D. Teschner and P. Strasser, Angew. Chem., 2015, 54, 2975-2979.
14. T. Reier, D. Teschner, T. Lunkenbein, A. Bergmann, S. Selve, R. Kraehnert, R. Schlögl and P. Strasser, J. Electrochem. Soc., 2014, 161, F876-F882.
15. H. N. Nong, L. Gan, E. Willinger, D. Teschner and P. Strasser, Chem. Sci., 2014, 5, 2955-2963.
16. A. Bergmann, I. Zaharieva, H. Dau and P. Strasser, Energy Environ. Sci., 2013, 6, 2745-2755.
17. H. Dau, C. Limberg, T. Reier, M. Risch, S. Roggan and P. Strasser, Chemcatchem, 2010, 2, 724-761.
18. A. S. Varela, N. Ranjbar, J. Steinberg, W. Ju, H.-S. Oh and P. Strasser, Angewandte Chemie - International Edition, 2015, online DOI: 10.1002/anie.201502099.
19. R. Reske, H. Mistry, F. Behafarid, B. Roldan Cuenya and P. Strasser, J. Am. Chem. Soc., 2014, 136, 6978-6986.
20. H. Mistry, R. Reske, Z. Zeng, Z.-J. Zhao, J. Greeley, P. Strasser and B. Roldan Cuenya, J. Am. Chem. Soc., 2014, 136, 16473-16476.
21. Ana Sofia Varela, Matthias Kroschel, Tobias Reier and P. Strasser, Catal. Today, 2015, doi:10.1016/j.cattod.2015.1006.1009.
Prof. Dr. Rony Snyders
15.07.2015Plasma polymerization (diagnostic + growth mechanism)
Head of the research laboratory ChIPS (Chimie des Interactions Plasma-Surface)
Place: Sala de Reuniones del CicCartuja2 | 15.00 h
In the framework of our activities in the field of plasma polymerization, we are interested in contributing towards a better understanding of the growth mechanism of the plasma polymer films which is of tremendous importance for a better control of the material properties. To reach this goal, our systematic strategy is based on a multidisciplinary approach combining plasma diagnostic and thin film characterization. The latter is mainly achieved through XPS measurements most of the time combined with chemical derivatization methods as well as ToF-SIMS measurements. On the other hand, the plasma chemistry is investigated by using Mass Spectrometry and FTIR spectroscopy. For both methods, the data are evaluated using an original approach using DFT calculations. We have recently shown that this approach allows to significantly improve the understanding of the different reactions pathways encountered by the precursor. In the future, based on our recent achievements in clarifying the growth mechanism of several families of plasma polymers, our objective is to go one step further by investigating the chemical reactivity of film-forming species towards the growing film. In addition, in order to get a more complete picture of the mechanisms, strong efforts will be devoted to characterize the electrons as well as the ions by dedicated diagnostic methods.
Prof. Lorenzo Pavesi
28.05.2015Silicon nanocrystals as enabler for silicon photonics
Universidad de Trento (Italia)
Place: Salón de Actos del CicCartuja | 12.00 h
Low dimensional silicon nanocrystals (Si-nc) have interesting optical properties which enables different applications. On one side quantum confinement effects turn silicon into a luminescent material where luminescence can be also excited by electrical injection. On the other side, small sizes, large surfaces and dielectric mismatch between the core and the surrounding matrix increase dramatically the nonlinear optical coefficients.
In this talk I will review our recent work on Si-Nc and their applications:
- The growth and physics of Si-nc [Silicon Nanocrystals; Fundamentals, Synthesis and Applications (Wiley-VCH 2010)]
- The development of high efficiency solar cells with Si-nc downshifting layer [Solar Energy Materials and Solar Cells 132, 267 (2015)]
-The development of bipolar light emitting diodes [Journal of Applied Physics 111, 063102 (2012) Applied Physics Letters (2015);]
- The use of silicon nanocrystals light emitting diode as entropy source for quantum random number generation, the key device for cryptography [Journal of Ligthwave Technology (2015)];
- The use of silicon nanocrystals as nonlinear material in bistable optical cavities, in waveguide optical mode monitors which are based on two photon excited luminescence detection, in wavelength shifter by sum-frequency generation [Optics Letters 38, 3562 (2013); Applied Physics Letters 106, 071109 (2015).].
Dr. Miolaj Berczenko
21.05.2015TOF-SIMS for the analysis of surfaces
University of Rzeszow (Polonia)
Place: Seminario del CicCartuja | 10.30 h
Dr. Luis M. Liz-Marzán
07.05.2015Prospects for Plasmonic Nanomaterials
Bionanoplasmonics Laboratory, CIC biomaGUNE
Place: Salón de Actos del CicCartuja | 11.00 h
Metal nanoparticles display very interesting optical properties, related to localized surface plasmon resonances (LSPR), which give rise to well-defined absorption and scattering peaks in the visible and near-IR spectral range. Such resonances can be tuned through the size and shape of the nanoparticles, but are also extremely sensitive towards dielectric changes in the near proximity of the particles surface. Therefore, metal nanoparticles have been proposed as ideal candidates for biosensing applications. Additionally, surface plasmon resonances are characterized by large electric fields at the surface, which are responsible for the so-called surface enhanced Raman scattering (SERS) effect, which has rendered Raman spectroscopy a powerful analytical technique that allows ultrasensitive chemical or biochemical analysis, since the Raman scattering cross sections can be enhanced up to 10 orders of magnitude, so that very small amounts of analyte can be detected. This seminar will focus on recent developments and future prospects within the various areas involved in the development and application of plasmonic nanomaterials, from nanoparticle synthesis and assembly, through optical modeling, to the design of engineered substrates for sensing and diagnostics.
Dr. Hugo Rojas Sarmiento y Dra. Julie J. Murcia
24.03.2015Perspectivas de Investigación en Catálisis en Colombia – Análisis desde la Universidad Pedagógica y Tecnológica de Colombia
Grupo de Catálisis de la Universidad Pedagógica y Tecnológica de Colombia
Place: Salón de Actos del CicCartuja | 10.00 h
2014
2014
Dr. George Palasantzas
12.06.2014Casimir force between real materials for device applications
Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, The Netherlands
Place: Seminario del CicCartuja | 11.00 h
Using the measured optical response and surface roughness topography as inputs, we perform realistic calculations of the influence of Casimir forces on the actuation dynamics of micro/nanoelectromechanical systems (MEMS/NEMS). Amorphous to crystalline phase transitions in phase change materials can have strong influence on the actuation of microelectromechanical systems under the influence of Casimir forces. Indeed, the phase portraits of the actuation dynamics show strong sensitivity to changes of the Casimir force as the stiffness of the actuating component decreases and/or the effective interaction area of the Casimir force increases, which can also lead to stiction. Introduction, however, of intrinsic energy dissipation (associated with a finite quality factor of the actuating system) can prevent stiction by driving the system to attenuated motion towards stable equilibrium. It is also found that even though surface roughness appears to have a detrimental effect on the availability of stable equilibria, it ensures that those equilibria can be reached more easily than in the case of flat surfaces. Hence our findings play a principal role for the stability of micro/nanodevices and architectures operating at distances below 200 nm. Finally, new investigations for the Casimir force from conductive SiC and their implications for MEMS/NEMS will also be discussed.
2013
2013
Prof. Richard Partch
26.09.2013Enhancing Particle Applications by Surface Modification
Chemistry Center for Advanced Materials Processing Clarkson University
Place: Salón de Actos del CicCartuja
Gas, aerosol and liquid dispersion methods for particle synthesis and surface modification carried out by the speaker´s research group at Clarkson University will be presented. Briefly discussed will be colloids having a wide variety compositions, shapes and sizes useful for : 1) metal matrix and rubber composites, 2) protecting cores from acidic and humid environments, 3) improving print toner charging and reducing energy use by copy machines and fluorescent lights, 4) reducing polishing defects in microelectronic processing, 5) medical imaging, treatment of chemical overdoses and cancer and artificial organs and 6) security.
Dr. Timmy Ramírez-Cuesta
02.05.2013Espectroscopía de Neutrones, aplicaciones en Química, Ciencia de Materiales y Catálisis
ISIS Facility, STFC, Rutherford Appleton Laboratories, UK
Place: Sala Rotonda CicCartuja | 12.00 h
Las técnicas de neutrones son muy útiles en el estudio de la dinámica de los átomos y moléculas de hidrogeno. La naturaleza de la interacción entre el neutrón y átomo es responsable de la gran sección eficaz del núcleo del átomo de hidrogeno. En particular, el neutrón inspecciona simultáneamente la estructura y dinámica de los átomos del solido, en ambos casos la conexión entre los cálculos dinámicos utilizando métodos de DFT se corresponden rigurosamente con los espectros inelásticos dado que el neutrón interactúa directamente con el núcleo atómico, a diferencia del caso de las espectroscopias ópticas donde la dinámica del núcleo es determinada indirectamente a través de la interacción del fotón con la nube electrónica.
Otra característica muy importante de la interacción del neutrón es que es una prueba muy penetrante, por ejemplo, casi todos los metales poseen secciones eficaces muy pequeñas. Esto permite hacer experimentos utilizando contenedores de muestras de acero, aluminio etc., sin necesidad de tener ventanas ópticas, en consecuencia el uso de gases para dosificar solidos porosos, catalizadores y otros es trivial.
En esta charla se presentaran los aspectos básicos de la espectroscopia inelástica de neutrones y el uso de DFT para interpretar los experimentos como así también algunos ejemplos de aplicaciones al estudio de materiales solidos, gases adsorbidos en matrices porosas ( hidrogeno, captura de CO2, separación de etileno y acetileno entre otros)
Dra. Sol Carretero-Palacios
29.01.2013Plasmons in metallic hole arrays and nanoparticles in an optical trap
Photonics and Optoelectronics Group. Faculty of Physics and Center for Nanoscience (CeNS). Ludwing-Maximilians-Universität München
Place: Seminario de la primera planta del CicCartuja | 12.00 h
Subwavelength apertures periodically arranged in a metal film may transmit electromagnetic waves beyond the cutoff wavelength of the holes, with a much higher intensity than if they were isolated. It has been established that resonant excitation of surface plasmons creates huge electric fields at the metallic surface, forcing light through the holes and giving very high transmission coefficients. This is the so-called Extraordinary Optical Transmission.
I will present a detailed theoretical study of the physical mechanisms controlling the transmission process in a Bull’s Eye Geometry (a single subwavelength circular hole surrounded by concentric annular grooves).
I will also show final results for other systems containing annular holes, such us arrays of annular dimples (of finite thickness) designed for detection in the terahertz regime, and a description for resonances appearing at unusual wavelengths beyond the cutoff of the holes. Also the nonlinear optical response in arrays of subwavelength slits in combination with nonlinear Kerr-type dielectrics will be shown.
Finally, I will describe the Dark Field Microscopy technique and present some of its applications for manipulating micro- and nano-particles (metallic, dielectric, and hybrid ones).
2012
2012
Dr. Xavier Le Guebel
08.11.2012Fluorescent noble metal nanoclusters for biomedical applications
Centro Andaluz de Nanomedicina y Biotecnología
Place: Seminario de la primera planta del CicCartuja | 12.30 h
Noble metal nanoclusters(NCs) received much attention in the last five years due to their photophysical properties and their applications in nanomedicine. Several groups have studied the origin of the fluorescence of NCs and their structure–property inside different cavities such as polymers [2], dendrimer [3] and proteins [4]. Few-atom nanoclusters differ from gold or silver nanoparticles in that they can be highly fluorescent, do not support a surface plasmon, and do not have the metallic and bulk-like properties of nanoparticles/nanocomposites [5]. This fluorescence is likely due to the transition of molecule-like electronic levels when subnanometer sizes are smaller than the Fermi wavelength (i.e. < 1 nm). Noble metal (Ag, Au, Pt) NCs were prepared in wet chemistry in biological templates: proteins (Bovine Serum Albumin, human Transferrin), peptide (Glutathione) and DNA, which act as reducing agent and stabilizer. Structural investigations indicate a covalent binding between the metal cluster to the template and confirm the role of the nature of the ligand to the optical properties of the metal nanoclusters. Photophysical studies suggest a relative high quantum yield, strong photostability, long lifetime with a fluorescence emission tunable in the visible range. Moreover, cytotoxicity and life experiments in cells and with mice highlight the potential of this new type of “non-toxic” fluorescent labels for imaging and targeting.
[1] C. D. Geddes, J. R. Lakowicz1, Journal of Fluorescence 12 (2002) : 121.
[2] H. W. Duan, S. M. Nie, Journal of the American Chemical Society 129 (2007) : 2412.
[3] J. Zheng, J. T. Petty, R. M. Dickson, Journal of the American Chemical Society 125 (2003) : 7780.
[4] X. Le Guevel, N. Daum,M. Schneider, Nanotechnology 22 (2011) 275103 (7pp).
[5] J. Zheng, P. R. Nicovich, R. M. Dickson, Annual Review of Physical Chemistry 58 (2007) : 409.
Prof. Dr. Anton Lerf
19.03.2012Intercalation of Hydrated Fe2+ and Fe3+ in the Vermiculites from Santa Olalla and Ojén. A Mössbauer spectroscopic investigation
Walther-Meißner-Institut der Bayerischen Akademie der Wissenschaften Walther-Meißner-Straße 8 85748 Garching
Place: Seminario de la primera planta del CicCartuja | 12.30 h
Intercalation of hydrated Fe2+ and Fe3+ ions in phyllosilicates is of interest for different fields of research, e.g. soil science, nutrition of plants, catalysis. However, the nature of intercalated species is not really clear up to now. We carried out Mössbauer investigation of Fe-intercalated vermiculites from Santa Olalla and Ojén. In case of the Fe3* intercalated vermiculites it is not possible to get intercalation without simultaneous deposition of iron oxyhydroxides on the external surface of the vermiculites. The intercalation of Fe2+ is much easier. This intercalated iron is highly mobile at room temperature. In addition, the Mössbauer data can be explained only if one assumes internal redox processes between intercalated and structural iron ions. Even in case of the Fe3+ intercalated vermiculites one can observe internal redox reactions.
Prof. S. Ted Oyama
07.03.2012Mechanism of Propylene Epoxidation on Gold/Titanosilicate Catalysts
The University of Tokyo Department of Chemical Systems Engineering 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
Place: Seminario de la primera planta del CicCartuja | 12.00 h
2011
2011
Prof. Jiří Málek
13.07.2011Structural Relaxation in Glasses and Supercooled Liquids
Department of Physical Chemistry, University of Pardubice, Czech republic
Place: Seminario de la primera planta del CicCartuja | 12.00 h
Structural relaxation strongly affects physical properties of non-crystalline materials. Different types of structural relaxation and measurement techniques are described. The link between relaxation behavior, viscous flow and crystal growth in highly supercooled liquids is discussed. Volume and enthalpy relaxation is interpreted within a phenomenological model that allows quantitative description and thermal treatment tailoring for effective and long term use of non-crystalline materials. Some general features of structural relaxation common to many different and chemically dissimilar glass-forming systems ranging from polymers to oxides, chalcogenides and metallic glasses are discussed.
José Ángel Martín Gago
31.03.2011Reacciones de Moleculas Orgánicas y Biomoleculas sobre Superficies de Monocristales
Instituto de Ciencia de Materiales de Madrid (CSIC)
Place: Seminario de la primera planta del CicCartuja | 12.00 h
Los procesos de auto-ensamblado y auto-organización de moléculas orgánicas sobre superficies son algunas de las principales estrategias que han permitido a la vida desarrollarse a partir de sus componentes moleculares (building blocks) y que han inspirado las nuevas tendencias de fabricación de dispositivos en lo que se ha llamado aproximación bottom-up. La estructura que adquieren las capas moleculares sobre superficies es fundamental para determinar muchas de sus posibles aplicaciones. Por tanto, técnicas de caracterización de superficies como XPS, LEED o DFT, y en especial STM que presentan una alta sensibilidad, nos proporcionan información sobre interacción química, estructura y propiedades electrónicas de las capas moleculares ensambladas. En esta presentación se describirán varios tipos de sistemas moleculares y se clasificarán por el grado de interacción que mantienen sobre el substrato, describiendo cuales son los mecanismos responsables de la estructura final. Las capas de PTCDA sobre Au(111) son un ejemplo de sistema muy poco interaccionante, que puede modificarse por la inclusión de átomos de Fe en la estructura. En el otro extremo, veremos sistemas basados en la interacción S-metal, como los alcanotioles, que presentan numerosas aplicaciones tecnológicas si se modifica el grupo funcional. Así veremos la estructura de capas de DNA, PNA o cisteina sobre diferentes substratos. Con respecto al DNA o PNA podremos relacionar la estructura molecular con parámetros tecnológicos como la eficiencia del biosensor.
Por último nos centraremos en describir como estos substratos pueden además ser utilizados para catalizar reacciones y formar nuevas moléculas, como fullerenos a partir de sus precursores moleculares, abriendo las puertas a un campo nuevo que permite la obtención de nuevas moléculas.
Prof. Josef Breu
27.03.2011Novel Materials Based on Modified and Synthetic Clays
Lehrstuhl für Anorganische Chemie I, Universität Bayreuth
Place: Seminario de la primera planta del CicCartuja | 12.00 h
The combination of platy morphology and high intracrystalline reactivity paves the way for a broad range of possible applications for layered silicates that extends far beyond the well established adsorptive and rheological materials. In particular, synthetic layered silicates are well suited to fabricate for instance microporous hybrid materials and polymer layered silicate nanocomposites with superior gas barrier, flame retardancy, and mechanical properties.
Dr. Lluís Marçal
24.03.2011Template-assisted fabrication and characterization of polymer nanopillar arrays for optoelectronic applications
Catedrático de la Universidad Rovira i Virgili, Tarragona Departamento de Ingeniería Electrónica, Eléctrica y Automática
Place: Seminario de la primera planta del CicCartuja | 12.00 h
Recently, photoluminescent conducting polymeric micro- and nanostructures have received a considerable attention because of their interesting optoelectronic properties and potential applications such as sensors, polymer light-emitting diodes, polymer solar cells, etc. Different synthesis methods have been proposed for the fabrication of polymer nanostructures: template-assisted, nanoimprinting, nanolithography and electro-spinning. Among them, template-assisted is an easy, low cost, and highly versatile method to fabricate nanostructures for a variety of materials: polymers, metals, inorganics, semiconductors and their multi-functional composites. This method entails microporous or nanoporous materials used as templates. The synthesized nanostructure is achieved by infiltration of the material within the pores of the template. After deposition, the template can be selectively removed either partially or completely to produce a nanostructure array or freestanding nanostructures. In addition, template-assisted techniques possess the advantage of being able to readily create large-area, ordered nanostructures and, in some cases, vertically aligned structures having high aspect ratios.
Anodized aluminium oxide (AAO) has become one of the most common nano-templates for the preparation of different nanometer-sized structures attractive because of its simple and highly controllable fabrication method. Dimensions as well as geometry of the nanostructures such as pore diameter and interpore distance can be controlled by selecting appropriate anodization conditions.
We present the fabrication and characterization of photoluminescent conducting polymer nanopillar arrays via template-assisted method. Different type of polymer nanopillar arrays were fabricated. The resulting polymer nanostructures are analyzed in detail by ESEM (environmental scanning electron microscopy) and AFM (atomic force microscopy) images. The effect of the nano-confinement on the electrical and optical properties is analyzed by current sensing atomic force microscopy (CS-AFM), photoluminescence and UV-Visible spectroscopy. In addition, the orientation of the polymer chains inside the nanopillar is also characterized by Raman spectroscopy and X-ray diffraction (µXRD). The results are discussed and compared with polymer thin films.
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