Directionally Designed Double Z‐Scheme Heterojunction: BiOBr and Carbon Dots‐Reduced TiO _2−x for Targeted Photocarriers Separation in Photocatalytic Sterilization

Abstract TiO ₂ photocatalysis holds promise for sterilization but faces limitations in rapid charge recombination, UV‐restricted activity, and pathogen electrostatic repulsion. Herein, a directionally designed double direct Z‐scheme BiOBr@CDs‐TiO _{2− x} heterojunction is constructed, in which defective BiOBr microspheres core with dominant (110) facets exhibiting photochromism via hole trapping is synergistically integrated with carbon dots (CDs)‐modified TiO _{2− x} shell. Amine‐functionalized CDs simultaneously reduce and dope TiO _{2− x} , thereby generating oxygen vacancies and enhancing positive surface charges. By leveraging BiOBr's hole‐trapping affinity and CDs’ electron‐transmitting capability, BiOBr@CDs‐TiO _{2− x} achieves spatial charge separation via a double Z‐scheme mechanism. This system eradicates 99.9% of Escherichia coli (5 × 10 ⁸ CFU mL ⁻¹ ), Staphylococcus aureus (2 × 10 ⁸ CFU mL ⁻¹ ), and Candida albicans (1 × 10 ⁸ CFU mL ⁻¹ ) in 1 h, concomitantly achieving biofilm clearance and pollutant degradation under visible light. The work pioneers CDs’ novel application in constructing oxygen vacancies of TiO _{2− x} and establishes a carrier‐affinity‐driven paradigm for directional heterojunction design.