Amorphous WSX as an efficient cocatalyst grown on CdS nanoparticles via photochemical deposition for enhanced visible-light-driven hydrogen evolution

Development of highly active and earth-abundant cocatalysts to replace scarce noble-metals is of great importance to realize large-scale and cost-efficient photocatalytic H-2 evolution reactions. Herein, we report that amorphous WSx cocatalyst grown on the CdS surface by a facile solution-based photochemical reduction method is an effective alternative for Pt cocatalyst and lead to superior photocatalytic H-2 evolution performances. Under visible light irradiation (>= 420 nm), the optimized CdS/WSx (12%) photocatalyst achieved a high initial H-2 evolution rate of 761 mu mol h(-1), which is the 17 times faster than that of CdS alone. Notably, the WSx cocatalyst shows a nearly 5 times higher activity than that of Pt in catalyzing H-2 evolution on CdS at same loading amount. An apparent quantum efficiency (AQE) of 14.7% was achieved over CdS/WSx (12%) at 420 nm. Moreover, CdS/WSx (12%) photocatalyst is relatively stable for 20 h H-2 evolution reactions, showing the robustness of WSx cocatalyst. Based on the results of photoelectrochemical and PL measurements, it was proposed that the amorphous WSx not only can rapidly capture photo generated electrons from excited CdS for enhancing the charge separation efficiency, but also promote the H+ reduction to H-2. Considering its high activity, easy-preparation, and low cost, the amorphous WSx cocatalyst would hold great potential in designing high-performance semiconductor/WSx photocatalysts for large-scale H-2 production using renewable energy sources. (C) 2017 Elsevier B.V. All rights reserved.