Novel g-C3N4/BiOClxI1-x nanosheets with rich oxygen vacancies for enhanced photocatalytic degradation of organic contaminants under visible and simulated solar light

Abstract A novel oxygen vacancy-rich g-C3N4/BiOClxI1-x heterostructure nanosheet (BCI-CN-P) is successfully prepared by a facile coprecipitation method with the assistance of surfactant polyvinylpyrrolidone (PVP) for enhanced photocatalytic degradation of organic contaminants. Field Emission Scanning Electron Microscope and Field Emission Transmission Electron Microscope detect the formation of heterostructure, while X-ray photoelectron spectroscopy and electron spin resonance demonstrate that the surface has rich oxygen vacancies. Under visible light irradiation, BCI-CN-P (g-C3N4/BiOClxI1-x with PVP) exhibits 100% photocatalytic degradation efficiency of colorless bisphenol A (BPA, 10 mg L−1) within 40 min, while CN (pure g-C3N4), BCI (pure BiOClxI1-x), BC-CN-P (g-C3N4/BiOCl with PVP) show negligible decomposition ability, and BCI-CN (g-C3N4/BiOClxI1-x without PVP) displays 61.2% removal efficiency for BPA after 1 h. Similarly, BCI-CN-P shows outstanding photocatalytic performance under simulated solar light, and the apparent reaction rate constant for BPA degradation is 0.2245 min−1, which is around 89.1, 15.2, 5.6 and 18.6 times as that of CN, BCI, BCI-CN and BC-CN-P, respectively. Furthermore, the photocatalytic mechanism of BCI-CN-P is revealed, the introduction of iodine and PVP enhance the visible light absorption ability and the formation of rich oxygen vacancies, and the synergistic effect between the g-C3N4/BiOClxI1-x heterojunction and oxygen vacancies facilitates the effective separation and transfer of photogenerated electron-hole pairs. O2·- radicals and photogenerated holes are confirmed to be main active species to decompose organic pollutants continuously during photocatalytic degradation process. The BCI-CN-P catalyst is excellent and applicable in the broad pH range from 5.0 to 9.0. Also, BCI-CN-P presents outstanding mineralization capability and bio-friendliness for potential practical application.