Facile Design of C-Doped g-C3N4/Ov-BiOBr Z-Scheme Heterostructure with High Photocatalytic Performance

Solar-driven photocatalysis has attracted increasing interest as an efficient and environmentally friendly approach for the mineralization of pollutants. In this work, carbon-doped g-C3N4/VoBiOBr composites rich in oxygen vacancy (denoted as CCN/VoBOB) were prepared by combining calcination with a solvothermal method, using glucose as the carbon source. The obtained composites were comprehensively characterized by XRD, TEM, and XPS to investigate their crystal structure, morphology, and surface chemical states, and their photocatalytic activity was evaluated through the degradation of organic pollutants. Among the prepared samples, 3.2 wt% CCN/VoBOB exhibited the best photocatalytic performance, reaching 98% degradation of Rhodamine B (RhB) and 95% degradation of Methylene Blue (MB) within 90 min, which was significantly superior to that of VoBOB and g-C3N4/VoBOB. This enhanced activity can be attributed mainly to the synergistic effects of oxygen vacancy, carbon doping, and heterojunction construction. Their combined action not only regulates the band structure of VoBOB effectively, but also greatly inhibits the recombination of photogenerated electron–hole pairs. These results were further supported by UV-Vis DRS and transient photocurrent measurements. Radical trapping experiments indicated that superoxide radicals (O2−) were the dominant active species during the reaction. In addition, density functional theory (DFT) calculations provided further evidence for the above conclusions. On the basis of both experimental observations and theoretical analysis, a reasonable photocatalytic reaction mechanism was proposed. This work offers a useful strategy for designing highly efficient photocatalysts through the synergistic integration of oxygen vacancy, nonmetal doping, and heterojunction engineering, and thus promotes the application of photocatalytic technology in pollutant degradation.