Defect engineering synthesis of oxygen-doped carbon nitride microtubules for enhanced visible-light-driven photocatalysis

Herein, a two-dimensional microtubule O-doped g-C₃N₄ photocatalyst was successfully synthesized via a H₂O₂-assisted hydrothermal method (V_water : V_{hydrogen peroxide} = 3 : 1, 180 °C). The unique two-dimensional tubular O-g-C₃N₄ exhibits a remarkable degradation efficiency of 87.7% for tetracycline within 60 minutes, together with an excellent hydrogen production rate of 613.67 μmol h^-1 g^-1. Oxygen doping modifies the material's band structure, narrows the band gap, and enhances its visible light absorption, thereby improving the utilization efficiency of visible light. The porous structure of O-g-C₃N₄ provides abundant active sites for photocatalytic reactions, enhancing the separation and transfer efficiency of electrons and holes, thereby substantially boosting the hydrogen production efficiency. This work demonstrates that defect engineering and doping can synergistically regulate the material's band structure and visible light absorption, enhance photoelectron transport and separation, and ultimately improve its photocatalytic degradation and hydrogen evolution performance.