MnOx-decorated 3D porous C3N4 with internal donor–acceptor motifs for efficient photocatalytic hydrogen production

Carbon nitride is an intriguing visible-light photocatalyst for H2 production but suffers from low surface area and fast charge recombination. Here, we report a simple yet efficient approach to fine tune the porous structure, modify the electronic structure and carrier behaviors of C3N4 through in-situ growth of MnOx by NaCl template-assisted strategy. This NaCl template method simultaneously constructs 3D porous structure for high surface area, induces Na coordination with N atoms and accompanying cyano group to form an internal donor-acceptor system for efficient charge transfer and separation. Along with the MnOx growth, the band gap of C3N4 is narrowed for stronger visible light absorption and the conduction band level is negatively shifted for stronger reduction capability. Thus, the resulted C3N4 (MSCN) shows much improved activity of about 18 times higher than bulk C3N4 in photocatalytic hydrogen evolution reaction under visible light irradiation.