Electronic structure modulation to enhance the internal electric field and artificial photosynthesis by Br introduction in layered BixOyBrz.

Bi_xO_yBr_z, as a new class of promising layered materials for photocatalysis, have been extensively applied in CO₂ reduction. Herein, a series of Bi_xO_yBr_z with varied Br concentrations were synthesized to probe the contribution of the Br element to the Bi electronic structure, which dominates the conduction band (CB) of Bi_xO_yBr_z materials. As the O atoms were replaced by the less-electronegative Br, the electronic environment around Bi³⁺ is altered, further resulting in a shift in the position of the E_CB for Bi_xO_yBr_z. Moreover, Br slabs are interleaved with the [BiO] layers, resulting in increased internal electric field (IEF) strength, which provides a strong driving force for the mobilization of photogenerated carriers. In conjunction with the optimal band structure and efficient carrier separation, BiOBr exhibits the highest catalytic activity with a CO yield of 24.8 μmol g⁻¹. Meanwhile, in situ DRIFTS spectra illustrate the high-proportioned *CO₂⁻ active species on BiOBr, indicating the favorable conversion and activation of CO₂. This study may provide insights into the role of the Br element in Bi_xO_yBr_z materials and new opportunities for exploring efficient photocatalysts for CO₂ photocatalysis. [ABSTRACT FROM AUTHOR]