Fabrication of Mn/O co-doped g-C3N4: Excellent charge separation and transfer for enhancing photocatalytic activity under visible light irradiation

Abstract Co-doping has been proven to significantly enhance the photocatalytic performance of g-C3N4. Herein, Mn and O co-doped g-C3N4 (Mn/O-CN) composites were constructed for the first time by a simple one-pot calcining route. The systematic characterization results of XRD, FT-IR, TEM-EDS, XPS and DRS revealed that the Mn and O elements were co-doped into the CN framework successfully as Mn3+/4+ and n-π* conjugate forms, respectively. The as-prepared Mn/O-CN-2 achieved the highest visible-light-driven degradation rate constant of 0.0290 and 0.0267 min−1 for degradation of Malachite green (MG) and Amido black 10B (AB 10B), which were about 5.09 and 5.45 folds higher than that of pristine CN, respectively. The improved photocatalytic degradation property of Mn/O-CN were mainly benefited from the extended visible light utilization, the enlarged specific surface area, and the accelerated separation and transfer of photo-induced charge carriers, which were all induced by the synergistic effects of Mn and O co-doped. Finally, the active species capturing experiments proved that the superoxide radicals (·O2−) and holes (h+) acted as the predominant roles in the photocatalytic degradation process.