Lead-free halide perovskite Cs2AgBiBr6 microcrystals composited with core-shell Au@TiO2 nanospheres for efficient visible-light photocatalytic degradation of antibiotics

Antibiotic pollution is a pressing environmental concern that fosters the spread of antibiotic-resistant bacteria and contaminates water resources, threatening ecosystem stability and public health. Conventional wastewater treatments frequently fail to completely degrade antibiotic compounds, highlighting the need for alternative approaches. Photocatalytic degradation of antibiotics presents an efficient, safe, and eco-friendly approach for advancing environmental purification. Lead-free halide perovskites, as one of potential green photocatalysts, can harness light energy to drive chemical reactions for energy conversion. However, the photocatalytic performance of pure lead-free halide perovskites is limited by undesirable charge recombination and insufficient visible light absorption. In this work, a novel Z-scheme heterojunction photocatalyst based on the composite of Cs2AgBiBr6 (CABB) microcrystals and core-shell Au@TiO2 nanospheres has been constructed. The structural characteristics and photoelectrochemical properties of the CABB/Au@TiO2 composite photocatalyst were further studied in detail. The CABB/Au@TiO2 exhibited significantly improved photocatalytic performance in the visible-light degradation of antibiotics, benefiting from the synergy between metallic surface plasmon resonance (SPR) effect and heterojunction construction. The optimal composite achieved degradation efficiencies of 99.6 % for sulfamethoxazole (SMX) and 99.3 % for sulfadiazine (SD) in the ethanol phase within 30 min, which has 14.4times and 18.1-times enhancement compared to that of pure CABB, respectively. More importantly, the CABB/ Au@TiO2 demonstrated good repeatability and long-term stability in the photocatalytic process. The primary results provide valuable guidance for the design of stable perovskite-based photocatalysts for effective environmental remediation.