In situ growth of vanadia-titania nano/micro-porous layers with enhanced photocatalytic performance by micro-arc oxidation

Micro-arc oxidation process was used to synthesize V2O5-TiO2 porous layers for the first time. Surface morphology and topography of the layers were investigated by scanning electron microscope (SEM) and atomic force microscope (AFM). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques were also employed to evaluate phase structure and chemical composition of the layers. It was found that the V2O5-TiO2 layers consisted of anatase, rutile, and vanadium pentoxide phases fraction of which varied with the applied voltage and the electrolyte concentration. It was also revealed that pore size and surface roughness increased with the applied voltage and the electrolyte concentration. Optical properties of the layers were studied by a UV-vis spectrophotometer, and the band gap energies of the MAO-grown pure TiO2 and V2O5-TiO2 layers were respectively calculated as 3.21 and 2.56 eV. Furthermore, the composite layers exhibited a significantly enhanced photo-activity when compared to pure TiO2 layers. The photocatalytic reaction rate constants of degradation of methylene blue on the surface of the V2O5-TiO2 layers under ultraviolet and visible irradiations were measured as 0.0228 and 0.0117 min(-1), respectively. As a consequence, micro-arc oxidation was deduced to be an appropriate and efficient method for synthesis of V2O5-TiO2 porous layers. (C) 2010 Elsevier Ltd. All rights reserved.