Energy band engineering and interface transfer strategies to optimize photocatalytic hydrogen evolution performance

The design of energy band structures and the construction of composite materials are effective ways to improve photocatalytic activity. Hence, Zn x Cd 1−x In 2 S 4 /MoS 2 composites were first prepared in this work by combining Zn x Cd 1−x In 2 S 4 solid solution and MoS 2 nanosheets. The solid solution strategy partly avoided the potential conflicts between visible-light absorption and redox capacity through energy band modulation, and MoS 2 provided more active sites and facilitated the separation of photogenerated carriers. This reasonable structural design improved the visible-light absorption capacity, achieved the appropriate redox potential, promoted carrier separation and transfer during photocatalysis. As-prepared composites of Zn 1/2 Cd 1/2 In 2 S 4 /MoS 2 -18.9% showed excellent photocatalytic hydrogen evolution performance under visible-light illumination, which provided a hydrogen evolution rate of 2255.21 μmol g −1 h −1 with an quantum yield of 19.55% under incident monochromatic light of 420 nm. Zn 1/2 Cd 1/2 In 2 S 4 /MoS 2 composites also displayed long-term stability after five photocatalytic cycles. Finally, the relevant photogenerated charge transfer and catalytic mechanisms of Zn x Cd 1−x In 2 S 4 and Zn 1/2 Cd 1/2 In 2 S 4 /MoS 2 composites were proposed and analyzed.