Probing the photocatalytic CO2 reduction potential of non-stoichiometric bismuth oxyhalides: A case study on Bi24O31BrxI10-x nanosheets

Abstract

Photocatalysts offer a promising approach for utilizing light energy to drive chemical reactions that traditionally require high energy inputs. Among the extensively researched compounds for photocatalysis, non-stoichiometric bismuth oxyhalides stand out due to the capacity of manipulating their bandgap and band structure, enhancing efficiency. This study presents the synthesis of Bi24O31BrxI10-x through a single-step solid-state reaction. Field-emission scanning electron microscopy (FESEM) unveiled the sheet-like morphology, while X-ray photoelectron spectroscopy (XPS) confirmed their chemical purity. X-ray diffraction (XRD) validated the phase-pure monoclinic structure, and transmission electron microscopy (TEM) affirmed their good crystallinity. UV–Vis diffuse reflectance spectroscopy (DRS) demonstrated a decreasing bandgap in Bi24O31BrxI10-x with increased iodine concentration. Efficiency of Bi24O31Br8.5I1.5 towards the degradation of methylene blue dye molecules was more than twice in comparison to Bi24O31Br10. For gas phase photocatalytic carbon dioxide (CO2) reduction, Bi24O31Br10 exhibited the best performance, producing 161 μmol g−1 of CO and 15 μmol g−1 of CH4, which were more than twice the amounts produced with Bi24O31Br8.5I1.5. These findings not only contribute to the understanding of solid-solution photocatalysts but also propose a scalable and easy production method, offering promising solutions for practical photocatalytic applications across environmental and industrial realms. © 2024 Elsevier Ltd