Enhanced photocatalytic hydrogen evolution on TiO2 employing vanadium carbide as an efficient and stable cocatalyst

Abstract

In an attempt to construct efficient and robust photocatalysts/systems for solar H2 evolution from water splitting, the development of highly active and stable H2 evolution cocatalysts is crucial yet remains a great challenge. Herein, we present that vanadium carbide (VC) can serve as an efficient cocatalyst when integrated with TiO2 for photocatalytic H2 evolution. With 15 wt% VC, the obtained TiO2/VC (15 wt%) composite photocatalyst (denoted as TV15) shows the highest photocatalytic H2 evolution rate of 521.4 μmol h−1 g−1, while the pristine TiO2 hardly shows H2 evolution activity. The apparent quantum efficiency (AQE) of H2 evolution reaches up to 2.3% under light irradiation of 365 nm. Notably, the TV15 exhibits excellent photocatalytic stability for H2 evolution over four cycles of continuous light irradiation of 20 h. The enhanced activity of TV15 can be attributed to the cocatalyst effects of VC, which can not only effectively capture the photogenerated electrons of TiO2 to greatly enhance the charge separation efficiency but also significantly reduce the overpotential of H2 evolution reaction, thus enhancing the photocatalytic activity of TiO2/VC towards H2 evolution. This work provides a new insight to rationally design and develop efficient photocatalysts using active and stable transition metal carbides as cocatalysts.