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

Co3O4 is anattractive semiconductor in thephotocatalytic field due to its proper band gap; however, its energylevel structure is mismatched for H-2 evolution. Herein,the Co3O4-based photocatalysts, Co3O4 nanosheet/g-C3N4 hybrids, weresuccessfully prepared by an ultrasonic self-assembly method for enhancedphotocatalytic H-2 evolution. The optimized hybrid with20 wt % g-C3N4, 20-CNCo, displayed the bestphotocatalytic performances, and the average H-2 evolutionrate was 134.6 mu mol center dot g(-1)center dot h(-1). The enhanced photocatalytic H-2 evolution activitiesof 20-CNCo were due to the formation of heterojunctions between Co3O4 nanosheets and g-C3N4,which can increase the optical absorption ability, promote the separationof photogenerated charges, accelerate the electron transfer, and prolongthe lifetime of the excited electrons. Moreover, following the uniquestep-scheme (S-scheme) charge transfer mechanism, the strong redoxability of the Co3O4 nanosheet/ g-C3N4 hybrid was retained, which was beneficial to the H-2 evolution. This work provides strategies for designing activecatalysts for photocatalytic reactions.

Automated summary

Co3O4 nanosheet/g-C3N4 hybrids, with the optimized hybrid of 20 wt % g-C3N4 (20-CNCo) displaying the best photocatalytic performances for H-2 evolution, with an average H-2 evolution rate of 134.6 mu mol center dot g(-1)center dot h(-1). The enhanced photocatalytic H-2 evolution activities of 20-CNCo were attributed to the formation of heterojunctions between Co3O4 nanosheets and g-C3N4, increasing optical absorption ability, promoting charge separation, accelerating electron transfer, and prolonging excited electrons' lifetime. The unique S-scheme charge transfer mechanism retained strong redox ability, contributing to H-2 evolution. This work provides strategies for designing active catalysts for photocatalytic reactions.