Co₃O₄ Nanosheet/g-C₃N₄ Hybrid Photocatalysts for Promoted H₂ Evolution

Co 3 O 4 is an attractive semiconductor in the photocatalytic field due to its proper band gap; however, its energy level structure is mismatched for H 2 evolution. Herein, the Co 3 O 4 -based photocatalysts, Co 3 O 4 nanosheet/g-C 3 N 4 hybrids, were successfully prepared by an ultrasonic self-assembly method for enhanced photocatalytic H 2 evolution. The optimized hybrid with 20 wt % g-C 3 N 4, 20-CNCo, displayed the best photocatalytic performances, and the average H 2 evolution rate was 134.6 μmol·g –1 ·h –1 . The enhanced photocatalytic H 2 evolution activities of 20-CNCo were due to the formation of heterojunctions between Co 3 O 4 nanosheets and g-C 3 N 4, which can increase the optical absorption ability, promote the separation of photogenerated charges, accelerate the electron transfer, and prolong the lifetime of the excited electrons. Moreover, following the unique step-scheme (S-scheme) charge transfer mechanism, the strong redox ability of the Co 3 O 4 nanosheet/ g-C 3 N 4 hybrid was retained, which was beneficial to the H 2 evolution. This work provides strategies for designing active catalysts for photocatalytic reactions.