Edge electronic vacancy on ultrathin carbon nitride nanosheets anchoring O2 to boost H2O2 photoproduction

The utilization of solar energy for hydrogen peroxide (H2O2) production using graphitic carbon nitride (g-C3N4) under visible light irradiation has attracted increasing interests due to its high efficiency and cost-effectiveness. However, this process is still limited by slow charge carrier migration. In this work, continuous regulation of band structure inside g-C3N4 is obtained by defect engineering through gradient calcination. The H2O2 production rate (4980 mu mol g-1 h-1) of nitrogen-defective g-C3N4 is 18 times higher than that of pristine g-C3N4. The pi*C--N-C signals in X-ray absorption near-edge structure spectrum decline, indicating an increased N-defects. The N-defects with the electronic vacancies in the heptazine intensifies its light-harvesting on g-C3N4 and also improve the selectivity of 2-electron O2 reduction. A quantitative structure-activity relationship between Ndefects and band structure is unveiled. This work offers an accessible strategy to design photocatalysts with desirable defect structures for energy conservation.