Scientific Papers in SCI

In this work, a facile method was used to synthesize the Zn3(PO4)2/BiPO4 composite photocatalysts with different Bi contents followed by heat treatment at 900 °C for 3 h. The as-prepared samples were studied by a variety of characterization techniques including X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) combined with energy dispersive X-ray diffraction (EDX), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (DRS). The UV–vis spectroscopy was used to analyze the evolution of Rhodamine B discoloration in presence of the synthesized phosphate photocatalysts. The XRD, SEM-EDX, TEM, DRS and XPS analyses confirmed the formation of heterojunction structure between both materials, during the process of co-precipitation and ulterior heat treatment. The photocatalytic tests showed that photocatalytic ability of the 70% Bi-Zn3(PO4)2 composites was higher than that of pure Zn3(PO4)2 and BiPO4 after 1 h of UV-illumination. The obviously enhanced photocatalytic activity of the 70% Bi-Zn3(PO4)2 sample could be mainly attributed to the formation of the heterojunction, accelerating the separation of photogenerated charge carriers. A plausible mechanism of the photocatalytic degradation of RhB on Zn3(PO4)2/BiPO4 composites is proposed. The reduction in the Chemical Oxygen Demand (COD) revealed the mineralization of dye along with color removal. Thus, it can be suggested that the 70% Bi-Zn3(PO4)2 can serve as a promising photocatalyst in the degradation of organic contaminants under UV light.

An original (beta + gamma)-TiNbTa material was manufactured by an optimised powder metallurgy treatment, based on a mechanical alloying (MA) synthesis, carried out at low energy, and a subsequently field assisted consolidation technique, the pulsed electric current sintering (PECS). The successful development of this (beta + gamma)-TiNbTa material was possible by the optimisation of the milling time (60 h) for the MA synthesis and the load and sintering temperature for the PECS (30 MPa and 1500 degrees C), as key parameters. Furthermore, the selected heating and cooling rates were 500 degrees C min(-1) and free cooling, respectively, to help maintain the lowest particle size and to avoid the formation of a detrimental high stiffness, hexagonal (alpha)-Ti alloy. All these optimised experimental conditions enabled the production of a full densified (beta + gamma)-TiNbTa material, with partially nanostructured areas and two TiNbTa alloys, with a body centred cubic (beta) and a novel face-centred cubic (gamma) structures. The interesting microstructural characteristics gives the material high hardness and mechanical strength that, together with the known low elastic modulus for the beta-Ti alloys, makes them suitable for their use as potential biomaterials for bone replacement implants.

A highly faceted {001} TiO2 catalyst was hydrothermally synthesized by using Ti(IV)-isopropoxide precursor with aqueous HF addition. WO3 was synthesized by following a reported method. Coupled TiO2-WO3 samples were synthesized by adding the corresponding amount of WO3 to fluorinated TiO2 gel followed by a hydrothermal treatment. Additionally the synthesized systems were characterized by using X-ray powder diffraction (XRD), X-ray fluorescence spectrometry (XRF), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS) and N2-adsorption (BET) for specific surface area determination. The photocatalytic activity of the single and coupled oxides was measured by means of three model reactions: the photo-oxidation of phenol (as a colourless substrate) and methyl orange (as a dye) and the photoreduction of Cr(VI) as K2Cr2O7. The coupling of WO3 with a highly faceted {001} TiO2 makes it possible to optimize the photocatalytic properties of the faceted material. In fact, {001} faceted TiO2 by itself presents a substantial improvement with respect to commercial TiO2(P25), as it can implement its photoactivity after the incorporation of WO3 with promising results, which can reduce the limitations of TiO2 in terms of its photoactivity, taking advantage of a higher percentage of solar radiation.

Until recently, superhydrophobicity was considered as a hint to predict surface icephobicity, an association of concepts that is by no means universal and that has been proven to depend on different experimental factors and material properties, including the actual morphology and chemical state of surfaces. This work presents a systematic study of the wetting and freezing properties of aluminum Al6061, a common material widely used in aviation, after being subjected to nanosecond pulsed IR laser treatments to modify its surface roughness and morphology. All treated samples, independent of their surface finishing state, presented initially an unstable hydrophilic wetting behavior that naturally evolved with time to reach hydrophobicity or even superhydrophobicity. To stabilize the surface state and to bestow the samples with a permanent and stable hydrophobic character, laser-treated surfaces were covered with a thin layer of CFx prepared by plasma-enhanced chemical vapor deposition. A systematic comparison between freezing delay (FD) and wetting properties of water droplets onto these plasma-/polymer-modified laser-treated surfaces that, under conditions where a heterogeneous nucleation mechanism prevails, surface morphology rather than the actual value of the surface roughness parameter the key feature for long FD times. In particular, it is found that surface morphologies rendering a Cassie-Baxter wetting regime longer FDs than those characterized by a Wenzel-like wetting state. It is that laser treatment, with or without additional coverage with thin CFx coatings, affects wetting and ice formation behaviors and might be an efficient procedure to mitigate icing problems on metal surfaces.