The introduction of carbon nanosheet buffer layer for enhanced hydrogen evolution performance of C3N4/CoP photocatalysts

Various defects of nanocomposites inevitably bring some harmful effects on their photoelectric performance, especially considering that interface defects seriously hinder the carrier interfacial transfer. Here, the interface optimization can be realized between graphitic carbon nitride (C 3 N 4 ) and CoP co-catalyst by the introduction of good conductive carbon nanosheets (CNs). As a result, the defect density of synthesized C 3 N 4 /CNs/CoP is reduced to 1.40 × 10 12  cm −3 from 2.55 × 10 12  cm −3 of C 3 N 4 /CoP, and its interface impedance is correspondingly reduced to 34% of that of C 3 N 4 /CoP. Therefore, the optimal H 2 evolution rate of 5.26 mmol g −1  h −1 and apparent quantum efficiency of 9.27% at 420 nm are realized, which are 4.8 and 8.1 times that of C 3 N 4 /CoP photocatalyst in the absence of CNs, respectively. This work provides a general solution to reduce defect density and carrier transfer resistance in nanocomposites by the introduction of a highly conductive buffer layer.