Oxygen-modified graphitic carbon nitride with nitrogen-defect for metal-free visible light photocatalytic H₂O₂...

Photocatalytic oxygen reduction is regarded as the cleanest approach for the production of hydrogen peroxide (H₂O₂). Herein, oxygen-modified graphite carbon nitride (g-C₃N₄) with nitrogen-defect (namely g-C₃N₄-ND4-OM3) was synthesized by a feasible method. Owing to the existence of nitrogen vacancy and oxygen-containing functional group, the absorption bands derived from n → π* and π → π* electronic transitions were enhanced, thereby enlarging the visible light response range of catalysts. Interestingly, nitrogen-defect can capture electron and effectively suppress the recombination of photoinduced electrons and holes. More importantly, the introduction of oxygen-containing functional groups can improve the hydrophilicity of g-C₃N₄, which was beneficial for the adsorption of dissolved oxygen. The electrostatic potential distributions of g-C₃N₄-based photocatalyst structural unit were also changed after introducing nitrogen vacancy and oxygen-containing functional group, and the electron-donating ability of g-C₃N₄ was improved. As a result, the evolution rate of H₂O₂ catalyzed by g-C₃N₄-ND4-OM3 was as high as 146.96 μmol/g/L under visible light irradiation. The photocatalytic H₂O₂ generation was completed through the direct 2-e^- oxygen reduction. In short, current work will share novel insights into photocatalytic H₂O₂ generation over g-C₃N₄-based catalyst.