Construction of S-scheme heterojunction via Cu2ZnSnS4 coupled with g-C3N4 for enhancing HER performance

It is shown that replacing non-noble metals with noble metals in photocatalytic water splitting is pivotal for increased and sustained hydrogen production. However, the challenge persists in designing and developing a cost-effective, highly active catalyst with effective carrier separation and providing sufficient H+ reduction sites to enhance photocatalytic H2 evolution efficiency. Herein, a series of S-scheme Cu2ZnSnS4/g-C3N4 (CZTS/CN) heterojunction composites were prepared via the hydrothermal method, followed by comprehensive characterizations for in-depth investigation. The TEM image exhibits a clear interface, showing the heterojunction formation between CZTS and CN nanosheets. The results show that incorporating CZTS cocatalyst significantly improves CN photocatalytic hydrogen evolution reaction (HER) and its performance is notably influenced by CZTS to CN mass ratio. Among CZTS/CN heterojunction composites, the 5% CZTS/CN heterojunction composite exhibited a significantly improved HER of 243.64 mu mol g- 1h- 1, which is 29.4 and 7.08 folds superior as compared to CN (8.29 mu mol g- 1h- 1) and CZTS (34.42 mu mol g- 1h- 1), respectively. The mechanism study revealed that the excellent superior H2 evolution performance resulted from the established internal electric field (IEF) in p-n heterojunction, which expedites the efficient separation and migration of photoinduced carriers coupled with the distinctive flower-like configuration of CZTS offering a substantial surface area and enough active reduction sites for photocatalysis process. This work presents a rational design and an inexpensive and efficient heterojunction photocatalysis system suitable for diverse applications.