Organic molecule bifunctionalized polymeric carbon nitride (MBCN) with edge-grafted and interchain-embedded benzene rings as the respective electron-donating group and charge-transfer channel exhibits significantly enhanced photocatalytic H₂O₂ production activity due to the promoted separation/transfer of photogenerated charge carriers and visible light absorbance. Based on density functional theory calculation and experimental results, we propose the transfer path of photogenerated electrons.

Abstract

Modifying the polymeric carbon nitride (CN) with organic molecules is a promising strategy to enhance the photocatalytic activity. However, most previously reported works show that interchain embedding and edge grafting of the organic molecule can hardly be achieved simultaneously. Herein, we successfully synthesized organic molecule bifunctionalized CN (MBCN) through copolymerization of melon and sulfanilamide at a purposely elevated temperature of 550 °C. In MBCN, the edge grafted and interchain embedded benzene rings act as the electron-donating group and charge-transfer channel, respectively, rendering efficient photocatalytic H₂O₂ production. The optimal MBCN exhibits a significantly improved non-sacrificial photocatalytic H₂O₂ generation rate (54.0 μmol g⁻¹ h⁻¹) from pure water, which is 10.4 times that of pristine CN. Experimental and density functional theory (DFT) calculation results reveal that the enhanced H₂O₂ production activity of MBCN is mainly attributed to the improved photogenerated charge separation/transfer and decreased formation energy barrier (▵G) from O²⁻ to the intermediate 1,4-endoperoxide (⋅OOH). This work suggests that simultaneous formation of electron donating group and charge transfer channel via organic molecule bifunctionalization is a feasible strategy for boosting the photocatalytic activity of CN.