Enhancing an internal electric field by a solid solution strategy for steering bulk-charge flow and boosting photocatalytic activity of Bi24O31Cl Br10–

Constructing bismuth oxyhalide solid solutions with a single homogeneous phase have intrigued the research community; however, a deeper understanding of the intrinsic origin for improved bulk-charge separation is still unclear. Herein, a series of Bi24O31ClxBr10–x solid solutions with the same structural characteristics were synthesized by crystal structure regulation. Combining density functional theory calculation, Kelvin probe force microscopy, and zeta potential testing results, an enhanced internal electric field (IEF) intensity between [Bi24O31] and [X] layers was achieved by changing halogen types and ratios. This greatly facilitated bulk-charge separation and transfer efficiency, which is significant for the degradation of phenolic organic pollutants. Owing to the enhanced IEF intensity, the charge carrier density of Bi24O31Cl4Br6 was 33.1 and 4.7 times stronger than that of Bi24O31Cl10 and Bi24O31Br10, respectively. Therefore, Bi24O31Cl4Br6 had an optimal photoactivity for the degradation of bisphenol A, which was 6.21 and 2.71 times higher than those of Bi24O31Cl10 and Bi24O31Br10, respectively. Thus, this study revealed the intrinsic mechanism of the solid solution strategy for photocatalytic performance enhancement with respect to an IEF.