Surface-surface contacted direct Z-scheme TiO₂-BiVO₄-PI heterostructure for enhanced photoelectrocatalytic...

Bisphenols (BPs) are a series of widely used endocrine disruptors, which potentially harm the environment and human health. In this work, a novel Z-scheme TiO₂-BiVO₄-PI heterostructure was synthesized, characterized, and used for the simulated sunlight-driven photoelectrocatalytic degradation of BPs. Due to the existence of surface-surface contacted direct Z-scheme between BiVO₄ and PI, holes were concentrated on the valence band of BiVO₄ and electrons were concentrated on the conduction band of PI, resulting in a stronger redox activity. All six BPs exhibited appreciable degradation following the order of bisphenol A (BPA, 93.5%) > bisphenol B (BPB, 92.7%) > bisphenol AP (BPAP, 85.6%) > bisphenol F (BPF, 75.9%) > bisphenol AF (BPAF, 69.8%) > bisphenol S (BPS, 39.2%), within 120 min under the optimal condition. In the process of degradation, superoxide radicals (·O₂^-) and hydroxyl radicals (·OH) played dominant roles, and the intermediates of BPs degradation were mainly formed via the substituent shedding or C-C bond breaking of phenol ring, hydroxylation, and ring opening of phenol ring. The ECOSAR program was used to analyze the changes in the toxicity of the intermediates, and it was proved that the toxicity showed a decrease trend during the degradation process. This study provides a Z-scheme mechanism for TiO₂-BiVO₄-PI, which can degrade BPs and reduce their toxicity effectively.