Visible light photocatalytic activity of metal (Mo/V/W) doped porous TiO2 coating fabricated on Cp-Ti by plasma electrolytic oxidation

Photocatalytic degradation under visible light region acquired a wide interest in the field of wastewater treatment. In this study, the transition metal ion (Mo/V/W) doped TiO2 layer was developed on commercially pure titanium (Cp-Ti), by plasma electrolytic oxidation (PEO), as an immobilized photo-catalytic surface for textile wastewater treatment application. The effect of transition metal ion (Mo/V/W) doping on TiO2 coating phase composition, surface morphology, corrosion, wettability, bandgap, charge separation and electron-hole recombination rate are investigated. The phase analysis of coatings showed that the dopants suppressed the formation of the rutile. The doped TiO2 samples exhibited higher surface porosity and active surface area, thereby enhancing the photocatalytic activity. Among the doped titanium oxides, W doped TiO2 exhibited superior charge separation with 95% degradation and 71% mineralisation of methylene blue dye under visible light irradiation for 180 min. This could be attributed to the synergistic effect of lower bandgap, high charge separation, and low electron-hole recombination rate. The present research positively demonstrated an efficient, visible light driven immobilized photo catalyst surface by a simple PEO process as a promising photocatalytic system in the quest for the development of low cost and sustainable process for textile wastewater treatment application. (C) 2020 Elsevier B.V. All rights reserved.