Vis-NIR responsive Bi24O31Br10 and corresponding composite with up-conversion phosphor towards efficient photocatalytic oxidation

CIn this work, series of Bi24O31Br10 semiconductors were respectively synthesized by precipitation, solvothermal and calcination methods to explore the influence of preparation methods on the photocatalytic performances of photocatalysts. The refractory antibiotics (CIP and TC) and low concentration of continuous flowing NO gas were used as photocatalytic targets with the irradiation of visible or NIR lights. Interestingly, Bi24O31Br10 fabricated by a simple room-temperature precipitation method (BOB-R) exhibited the best photocatalytic activity compared to the other two samples with high cost preparation. The characterizations and trapping experiments verified that the smaller nanoparticles, oxygen vacancy concentration, band structure and charge combination probability were contributed to the superior photocatalytic performance of Bi24O31Br10 prepared by precipitation method. Besides, due to the generation of oxygen vacancies, BOB-R sample not only showed excellent removal efficiency of NO by UV and short-wavelength visible light, but also had considerable photocatalytic activity induced by long-wavelength visible light (lambda > 510 nm). To further broaden the range of light response to near-infrared light, the up-conversion phosphors were used to couple with BOB-R sample at room temperature. The up-conversion phosphors/BOB-R composites exhibited good UV light, short-wavelength and long-wavelength visible lights caused photocatalytic removal of NO, meanwhile valuable NIR light driven performance was found.