Lead-Free Cs₂AgBiBr₆/TiO₂ S-Scheme Heterojunction for Efficient Photocatalytic Antibiotic Rifampicin Degradation

Exploring efficient and stable halide perovskite-based photocatalysts is a great challenge due to the balance between the photocatalytic performance, toxicity, and intrinsic chemical instability of the materials. Here, the environmentally friendly lead-free perovskite Cs₂AgBiBr₆ confined in the mesoporous TiO₂ crystal matrix has been designed to enhance the charge carrier extraction and utilization for efficient photocatalytic rifampicin degradation. The as-prepared Cs₂AgBiBr₆/TiO₂ catalyst was stable in air for over 500 days. An S-scheme heterojunction was formed between the (004) plane of Cs₂AgBiBr₆ and the (101) plane of TiO₂ through the Bi-O-Br bonds. The built-in electric field at the interface efficiently promoted the photoinduced charge separation and carrier extraction. The Cs₂AgBiBr₆/TiO₂-200 showed a 92.83% degradation efficiency of rifampicin within 80 min under simulated sunlight illumination (AM 1.5G 100 mW cm^-2). This work offers an effective way for the construction of halide perovskite-based photocatalysts with high photocatalytic performance, good stability, and low toxicity simultaneously.