Competition between oxidation and anti-oxidation to guarantee visible light activity for a TiO2-x photocatalyst from the dissolution of Ti0

In this study, we investigated the critical factor for promoting visible light photocatalytic hydrogen evolution using a TiO2 photocatalyst, which limits the amount of Ti3+ coexisting with the catalyst. Our goal was to establish a simple and cost effective oxidation and anti-oxidation competitive strategy to synthesize a TiO2-x photocatalyst containing Ti0, Ti2+, Ti3+, and Ti4+ and an appropriate concentration of Ti3+ from the oxidation of titanium metal. Finally, the band gap and charge recombination of the final products were successfully optimized by the cooperation of all of the components to achieve efficient visible light photocatalytic hydrogen evolution without the addition of any exogenous dopants, and an ideal quantum yield of approximately 4.28% was achieved at a wavelength of 480 nm. Although various methods have been attempted to preserve Ti3+, our strategy for preserving Ti3+ from the initial preparation to the final products represents a new approach to alter the activity of TiO2.