Deciphering the Roles of Diketone-Derived Defects on Graphite Carbon Nitride in Boosted Photocatalytic Production of H₂O₂

The identification of defects and their roles in photocatalytic production of hydrogen peroxide (H 2 O 2 ) with carbon nitride (CN) is a challenging but important task. Here, a simple route was employed to generate defects in CN by tuning the ratio of the two synthesis precursors: acetylacetone (AcAc) and urea. In this way, a set of modified CNs (A x CN) with dual defects (C doping and surface −OH modification) were successfully fabricated. The one with an AcAc-to-urea ratio ( x ) of 0.05 showed a photocatalytic H 2 O 2 production rate of 3.6 mmol·g –1 ·h –1, which was greater than most of the reported CNs. Moreover, the selectivity of H 2 O 2 production was increased from 60% (CN) to 85% (A 0.05 CN). On the basis of density functional theory and the first-principles calculation, the high performance of A 0.05 CN was attributed to the synergistic roles of the dual defects in oxygen reduction reactions. The C doping enhanced the anchoring of dioxygen, while the −OH group facilitated the diffusion of charge carriers. The finding here provides an insight into the defect engineering for green generation of H 2 O 2 .