Facile strategy to construction Z-scheme ZnCo2O4/g-C3N4 photocatalyst with efficient H2 evolution activity

A novel p-n heterojunction ZnCo2O4/g-C3N4 was firstly prepared via an accessible two-step refluxing-calcination process for efficient photocatalytic H-2 production. The synergistic effect between ZnCo2O4 nanoparticles and g-C3N4 nanosheets to provide the plentiful active sites and the lower H-2-evolution overpotential. The obtained 10%-ZnCo2O4/g-C3N4 hybrid achieved the highest H-2 production rate of 1530 mu mol g(-1) h(-1), which was 10 folds of bare g-C3N4 under the UV-Visible light, and also higher than that of Co3O4/g-C3N4 and ZnO/g-C3N4. According to the transient photocurrent responses, photoluminescence spectra and electrochemical impedance spectroscopy, the enhanced activity was ascribed to the higher separation efficiency of photo-excited electrons and holes via a Z-scheme charge transfer mechanism, which was confirmed through the capture experiment of active species. Moreover, the recycling experiments indicated that the composite has good photo-stability. This work provides a way to prepare the bimetallic oxides-based photocatalysts for the applications of energy conversion.