First-principles study of the effect of Bi content on the photocatalytic performance of bismuth bromide oxide-based catalysts

Abstract

A comprehensive analysis of Bi_xO_yBr_z has been carried out using first-principles density-functional theory (DFT) to explore the electronic structure, energy band structure, and essential properties related to its photocatalytic performance. DFT calculations reveal that BiOBr, Bi₄O₅Br₂, Bi₁₂O₁₆Br₅, Bi₂₄O₃₁Br₁₀, Bi₃O₄Br, and Bi₅O₇Br have different indirect bandgap values of 2.46 eV, 2.51 eV, 1.67 eV, 2.21 eV, 2.21 eV, and 2.87 eV, respectively, and these differences reflect the influence of material composition and structure on its electronic structure. When analyzing their optical characteristics, we observe that the dielectric function's real and imaginary components show peaks in the low-energy regime, indicating a material that is more responsive to light in these energy ranges. The absorption spectra show that the Bi_xO_yBr_z material absorbs the highest amount of UV light absorption, and as the ratio of Bi to Br changes, the absorption spectra exhibit a red shift, which enhances the material's visible light absorption and thus improves the utilization of light. These light absorption properties make Bi_xO_yBr_z materials potentially advantageous for enhancing photoelectric conversion efficiency, which is particularly important for producing microelectronic and optoelectronic devices.