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

Efficient H2O 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-C3N4 step-scheme (S-scheme) heterojunction photocatalysts are fabricated through in situ hydrothermal growth of 2D CdS nanosheets (NSs) on 2D g-C3N4 NSs. The results clearly confirm that the binary CdS/0.7g-C3N4 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-C3N4, respectively. The apparent efficiency of CdS/0.7g-C3N4 at 420 nm is 6.86%. Importantly, the as-prepared CdS/0.7g-C3N4 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-C3N4 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.