Low-Coordinated\nNitrogen Vacancies for Robust Visible-Light-Driven\nH<sub>2</sub>O<sub>2</sub> Production

The solar-powered photocatalytic oxygen reduction reaction\nis considered\na promising alternative method for H<sub>2</sub>O<sub>2</sub> production\nunder mild reaction conditions. However, the intrinsic competitive\npathway grossly inhibits the selectivity and final yield of H<sub>2</sub>O<sub>2</sub> accompanying the loss of photogenerated electrons\nduring the oxygen reduction reaction process. Herein, two-coordinate\nnitrogen (N<sub>2C</sub>) vacancy-rich g-C<sub>3</sub>N<sub>4</sub> (DCN<sub>1.2</sub>) was developed by polymerization pyrolysis using\nthe bottom-up strategy. DCN<sub>1.2</sub> with a low-coordinated N<sub>2C</sub>-vacancy enabled an enhanced H<sub>2</sub>O<sub>2</sub> production\nin a wide pH range. The optimized DCN<sub>1.2</sub> demonstrated a\nH<sub>2</sub>O<sub>2</sub> yield of 556.2 μmol·g<sub>cat</sub><sup>–1</sup>·h<sup>–1</sup> at pH = 10, which\nwas approximately 3 times higher than that of pristine CN (202.7 μmol\ng<sub>cat</sub><sup>–1</sup>·h<sup>–1</sup>). DFT\ncalculations and photochemical experimental results revealed that\nN<sub>2C</sub>-vacancies induced the asymmetric electron distribution\nof DCN, thereby facilitating electron transfer and promoting the O<sub>2</sub> adsorption/activation for H<sub>2</sub>O<sub>2</sub> production.\nAdditionally, EPR and <i>situ</i> FTIR measurements indicated\nthat DCN<sub>1.2</sub> could produce H<sub>2</sub>O<sub>2</sub> via\na sequential two-step single-electron pathway, thereby achieving efficient\nH<sub>2</sub>O<sub>2</sub> production with good selectivity. This\nstudy provides guidance for the rational design of defect-engineering\ng-C<sub>3</sub>N<sub>4</sub> catalysts for efficient photocatalytic\nH<sub>2</sub>O<sub>2</sub> generation.