In Situ Fabrication of Robust Cocatalyst‐Free CdS/g‐C3N4 2D–2D Step‐Scheme Heterojunctions for Highly Active H2 Evolution

Efficient H 2 O splitting for H 2 evolution over the semiconductor photocatalyst is a crucial strategy in the field of energy and environment. Herein, cocatalyst‐free 2D–2D CdS/g‐C 3 N 4 step‐scheme (S‐scheme) heterojunction photocatalysts are fabricated through in situ hydrothermal growth of 2D CdS nanosheets (NSs) on 2D g‐C 3 N 4 NSs. The results clearly confirm that the binary CdS/0.7g‐C 3 N 4 S‐scheme heterojunction shows the best H 2 production rate (15.3 mmol g −1 h −1 ) without using any cocatalyst, which is 3.83 times and 3060 times higher than those of pure CdS and g‐C 3 N 4 , respectively. The apparent efficiency of CdS/0.7g‐C 3 N 4 at 420 nm is 6.86%. Importantly, the as‐prepared CdS/0.7g‐C 3 N 4 S‐scheme heterojunction has good stability when continuously irradiated for 21 h. The improved stability and activity are attributed to the formation of the S‐scheme heterojunction, which can markedly accelerate the interfacial charge separation for surface reaction. It is expected that the design of robust cocatalyst‐free CdS/g‐C 3 N 4 2D–2D S‐scheme heterojunction can become a promising approach to develop the highly active H 2 evolution systems based on various kinds of conventional semiconductor NSs.