Manganese dioxides with different exposed crystal plane supported on g-C3N4 for photocatalytic H2 evolution from water splitting

A series of MnO2/g-C3N4 composites with different exposed crystal plane were successfully prepared by different synthesized method. UV–Vis, PL, ESR and electrochemical results suggest that the visible-light absorbance, photoexcited electron-separation efficiency and oxygen defects are greatly dependent on the exposed crystal-faceted MnO2 supported on g-C3N4. The experimental results display that the exposed crystal plane of MnO2 have great influences on the photocatalytic hydrogen evolution performance, and the m-MnOCN composite with exposed (111) crystal plane exhibits superior photocatalytic performance for the release of H2 under visible light irradiation, followed by the order of b-MnOCN [002]> p-MnOCN [110]. Moreover, Mechanism studies have shown that the possible mechanism of photocatalytic hydrogen evolution reaction is Z-scheme mechanism.