Photocatalytic overall water splitting hydrogen production over ZnCdS by spatially-separated WP and Co3O4 cocatalysts

Loading suitable oxidation and reduction cocatalysts on sulfide semiconductor photocatalysts for H2 and O2 production reaction still remain a great challenge. Herein, we present a simple physical mixing strategy to load reduction cocatalyst WP and oxidation cocatalyst Co3O4 co-modification ZnCdS (WP–Co/ZCS) with excellent photocatalytic water splitting activity. The co-modification of the double auxiliary catalysts can efficiently accelerate the separation of photocarriers, enhance the reaction kinetics and significantly advance the photocatalytic activity. The maximum hydrogen evolution rate of 21.44 mmol g-1 h-1 is attained over 10% WP-Co/ZCS photocatalyst, which is about 6.5 folds higher than bare ZnCdS, and a high photostability is also obtained. Meanwhile, a notable quantum efficiency of 27.6% at 420 nm and solar-hydrogen conversion efficiency (STH) of 1.57% are achieved, which is significantly surpassing many reported ZnCdS-based photocatalysts. Remarkably, an efficient and stable photocatalytic overall water splitting activity are achieved with hydrogen and oxygen generation rates of 61 μmol g-1 h-1 and 32.5 μmol g-1 h-1 for 10% WP-Co/ZCS, respectively. This work provides a new idea for designing oxidation and reduction dual-catalysts on ZnCdS nanoparticles to advance photocatalytic hydrogen generation performance and achieve pure water splitting.