Asymmetric electric field structure boosts photocharge spatial separation and transfer to enhance antibiotics removal: In-situ construction and directed induction

• The BiOI/BiOIO 3 heterostructures were constructed by in-situ thermal reduction. • Heterostructures disrupted the symmetry of BiOIO 3 ′s internal electric field. • Asymmetric electric field structures directionally induced photocharge separation. • BiOI/BiOIO 3 heterostructures enhanced photocatalytic degradation of antibiotics. The symmetric electric field structure within layered Bi-based photocatalysts hinders the long-distance transport and spatial separation of bulk photocharges. Herein, the BiOI/BiOIO 3 heterostructures featuring a strong interfacial electric field were prepared through in-situ hydrothermal reduction, disrupting the symmetry of the internal electric field in pristine BiOIO 3 . The intrinsic polarization electric field ({0 1 0}) and the interfacial electric field ({0 0 1}) within the BiOI/BiOIO 3 heterostructure directionally induced the separation and transport of photocharges along distinct pathways, significantly enhancing the dynamics of photogenerated charges and improving photocatalytic activity. Specifically, with the addition of 15 mL of glycol, the CBI-15 sample with a BiOI/BiOIO 3 structure achieved a 75.5 % removal rate of tetracycline and a 99.1 % removal rate of sulfisoxazole, which were 1.50 and 1.23 times higher than those of BiOIO 3 , respectively. Furthermore, continuous flow degradation experiments using photocatalytic membranes (CBI-PVDF) in real water media demonstrated the promising potential of CBI-15 for antibiotic removal. This work presents a novel approach to the directional induction of photocharges separation and transfer, providing valuable insights for developing highly efficient photocatalysts aimed at antibiotic removal.