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 (H2O2) 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 (AxCN) 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 H2O2 production rate of 3.6 mmol·g–1·h–1, which was greater than most of the reported CNs. Moreover, the selectivity of H2O2 production was increased from 60% (CN) to 85% (A0.05CN). On the basis of density functional theory and the first-principles calculation, the high performance of A0.05CN 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 H2O2.