Covalent-bond-enhanced photocatalytic hydrogen evolution of C₃N₄/CoP_x with L-cysteine molecule as bridging ligands

Serious interface carrier recombination leads to moderated photocatalytic performance of carbon nitride (C₃N₄), and the realization of their strongly covalent bonding with co-catalysts can efficiently inhibit this. In this article, C₃N₄ nanosheets are first functionalized with L-cysteine molecules to form C-SH bonds, and then the photodeposited CoP_x NPs are covalently bonded with C₃N₄ with L-cysteine molecules as bridging ligands, which can efficiently reduce the C₃N₄/CoP_x interface impedance. Their optimal hydrogen evolution rate and apparent quantum efficiency at 420 nm are 4.12 mmolg⁻¹h⁻¹ and 3.74%, respectively, which are 17.2 and 13.9 times that C₃N₄/CoP_x reference without L-cysteine bridging ligands, mainly due to the reduced C₃N₄/CoP_x interface impedance. This work proposes a general solution to inhibit interface carrier recombination in nanocomposites by introduction of bridging ligands.