Nickel single atoms anchored on ultrathin carbon nitride for selective hydrogen peroxide generation with enhanced photocatalytic activity

Photocatalysis technology provides a promising and effective method for hydrogen peroxide (H2O2) production. Nevertheless, the photocatalytic H2O2 production activity is greatly regulated by the two-electron oxygen reduction reaction (2e- O2RR). Herein, we demonstrate a robust single atom photocatalyst (NiCN-x, Ni single atoms anchored on ultrathin g-C3N4) for artificial H2O2 production under visible light irradiation. A high H2O2 generation rate of 27.11 mmol g- 1h- 1 and an apparent quantum yield (AQY) of 8.56 % at 400 nm are both obtained in the optimal NiCN-4 photocatalytic system. Furthermore, NiCN-4 catalyst shows relatively high selectivity of H2O2 with 87.3 % through using a rotating ring-disk electrode (RRDE) measurement. Furthermore, NiCN-4 shows enhanced photocatalytic TC decomposition with degradation efficiency of 89.4 %. Based on DFT calculation, experimental results and advanced characterizations, we find that the high photocatalytic performance is attributed to the boosting 2e- O2RR process with the formation of Ni-mu-peroxide (Ni-OOH) and the unique electronic feature of Ni-Nx coordination sites. This study offers a new blueprint for the fabrication of single atom catalysts (SACs) to achieve artificial photosynthesis of H2O2 with high selectivity and degradation of organic pollutants.

Automated summary

Photocatalysis technology shows promise in H2O2 production, but its activity is regulated by the 2e- O2RR. In this study, a robust single atom photocatalyst (NiCN-x) anchored on ultrathin g-C3N4 is demonstrated for artificial H2O2 production under visible light irradiation. The NiCN-4 catalyst exhibits high efficiency, selectivity, and degradation performance due to the boosting 2e- O2RR process and unique electronic structure.