Co-monomer engineering optimized electron delocalization system in carbon-bridging modified g-C3N4 nanosheets with efficient visible-light photocatalytic performance

The bridged nitrogen that linked each melem unit in g-C3N4 is considered to be sp(3) hybridization with a high electronegativity, which confines the original conjugate system of melon networks. Herein, the carbon-bridging modified g-C3N4 nanosheet (CBCN) is prepared by a one-pot copolymerization for the first time through employing malondiamide (MLDD) as a novel polymerized small molecule to urea. Experimental and DFT computation identify that substituting parts of bridged nitrogen in melon units with carbon not only improves the original conjugate system and optimizes the band structure of g-C3N4, but also induces the charges redistribution, leading to an enhanced charges separation and visible light utilization. Moreover, the MLDD co-monomer can act as a blocking agent to generate structure edge defects, which results in numerous in-plane holes and increases the specific surface area greatly. As a result, the CBCN samples show an excellent photocatalytic performance in degradation of pollutants and H-2 generation.