A bismuth-rich Bi₄O₅Br₂/TiO₂ composites fibers photocatalyst enables dramatic CO₂ reduction activity

Photocatalytic reduction technology of CO₂ can not only achieve energy saving and emission reduction, but also alleviate energy shortage, which is in line with today's concept of green and sustainable development. By employing electrospun TiO₂ nanofibers as substrate, bismuth- rich Bi₄O₅Br₂/TiO₂ composite fibers were prepared combining with in-situ hydrothermal reduction method. The composition, morphology and photoelectric properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electronmicroscopy (HRTEM), X-ray photoelectric spectroscopy (XPS), ultraviolet-visible absorption spectrum (UV-vis) and carbon adsorption. The results show that the band gap of Bi₄O₅Br₂/TiO₂ composite fibers becomes width, there is obvious absorption in the visible light band, and the reduction ability of photogenerated electrons is enhanced. Bi₄O₅Br₂/TiO₂ composite fibers can reduce CO₂ to CH₄ and CO, while the enrichment of the metal Bi can not only improve the adsorption capacity of the catalyst for acidic CO₂ molecules and enhance the conversion efficiency, but also change the photocatalytic reaction path and generate alcohol products such as CH₃OH. The CH₄, CO and CH₃OH yields of the optimized photocatalyst Bi@Bi₄O₅Br₂/TiO₂ composite fibers were 3.87, 1.06 and 0.32 μmol·h⁻¹·g⁻¹, respectively, after simulated sunlight irradiation 3 h. This work paves new opportunities for exploring high-efficiency CO₂ photoreduction catalysts.