Visible light driven (VLD) reduced TiO2−x nanocatalysts designed by inorganic and organic reducing agent-mediated solvothermal methods for electrocatalytic and photocatalytic applications

Abstract

This work presents a comparative study on the structural, optical and electrochemical characteristics of visible light driven (VLD) reduced titanium dioxide (TiO_2−x) nanocatalysts synthesized via inorganic and organic synthetic routes. X-ray diffraction (XRD) patterns, Raman spectra and X-ray absorption fine structure (XAFS) analyses reflected anatase phase titania. Whereas, the quantitative EXAFS fit and XANES analysis revealed structural distortion due to the presence of oxygen and titanium vacancies with low valent Ti states in anatase lattices of certain nanocatalysts, which subsequently leads to better electrochemical and photocatalytic activities. Moreover, owing to the large surface area and mesoporous structures, the Mg–TiO_2−x nanocatalysts exhibited enhanced water adsorption and ultimately increased overall water splitting with an OER overpotential equal to 420 mV vs. RHE at a current density of 10 mA cm⁻² (Tafel slope = 62 mV dec⁻¹), extended visible light absorbance, decreased photoluminescence (PL) intensity and increased carrier lifetime in comparison with commercial titania.