期刊
JOURNAL OF HAZARDOUS MATERIALS
卷 449, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.jhazmat.2023.131046
关键词
g-C3N4; N vacancy; Antibiotic degradation; Photocatalysis; Reactive oxygen species
Photocatalysis using N-vacancy-rich g-C3N4 (NvrCN) can effectively degrade organic pollutants and enhance the production of hydroxyl radicals (center dot OH) through the generation of superoxide radicals (O-2(center dot-)) during the photocatalytic process. This study presents a facile method for synthesizing NvrCN by post-solvothermal treatment of Mg-doped g-C3N4, which improves light-harvesting capacity, electron-hole separation, and charge transfer. NvrCN exhibits enhanced photocatalytic activity, degrading oxytetracycline 4-fold faster than pristine g-C3N4.
Photocatalysis offers opportunities to degrade recalcitrant organic pollutants without adding treatment chemicals. Nitrogen (N) vacancy is an effective point-defect engineering strategy to mitigate electron-hole recombination and facilitate hydroxyl radical (center dot OH) production via superoxide radical (O-2(center dot-)) generation during photocatalytic application of graphitic carbon nitride (g-C3N4). Here, we report a novel strategy for fabrication of N-vacancy-rich g-C3N4 (NvrCN) via post-solvothermal treatment of Mg-doped g-C3N4. The addition of the Mg precursor during the polycondensation of urea created abundant amine sites in the g-C3N4 framework, which facilitates formation of N vacancies during post-solvothermal treatment. Elemental analysis and electron paramagnetic resonance spectra confirmed a higher abundance of N vacancies in the resultant NvrCN. Further optical and electronic analyses revealed the beneficial role of N vacancies in light-harvesting capacity, electron-hole separation, and charge transfer. N vacancies also provide specific reaction centers for O-2 molecules, promoting oxygen reduction reaction (ORR). Therefore, center dot OH generation increased via enhanced formation of H2O2 under visible light irradiation, and NvrCN photocatalytically degraded oxytetracycline 4-fold faster with degradation rate constant of 1.85 x 10(-2) min(-1) (light intensity = 1.03 mW/cm(2), catalyst concentration = 0.6 g/L, oxytetracycline concentration = 20 mg/L) than pristine g-C3N4. Overall, this study provides a facile method for synthesizing N-vacancy-rich g-C3N4 and elucidates the role of the defect structure in enhancing the photocatalytic activity of g-C3N4.
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