Vanadium diboride as an efficient cocatalyst coupled with CdS for enhanced visible light photocatalytic H2 evolution

Exploiting active, stable, and cost-efficient cocatalysts is crucial to enhance the photocatalytic performance of semiconductor-based photocatalysts for H2 evolution from water splitting. Herein, we report on using vanadium diboride (VB2) as an efficient cocatalyst to enhance the photocatalytic H2 evolution performance of CdS nanoparticles under visible light irradiation (λ ≥ 420 nm). The CdS/VB2 composites prepared by a facile solution-mixing method exhibit much improved H2 evolution activities in 10 vol% lactic acid (LA) solution relative to pristine CdS. The most efficient CdS/VB2 composite with 20 wt% VB2 (CB20) exhibits a H2 evolution rate as high as 12.1 mmol h−1 g−1, which is about 11 times higher than that of CdS alone (1.1 mmol h−1 g−1). Moreover, the highest apparent quantum efficiency (AQE) of 4.4% is recorded on CB20 at 420 nm. The improved photocatalytic activity of CdS/VB2 composite can be attributed to the excellent cocatalytic effect of VB2, which can not only enhance the charge separation on CdS but also accelerate the H2 evolution kinetics. This work demonstrates the great potential of using transition metal brodies (TMBs) as efficient cocatalysts for developing noble-metal-free and stable photocatalysts for solar photocatalytic H2 evolution.