Halogen-Engineered Cs2AgBiX6/WS2 Composites With Enhanced Interfacial Dynamics for Efficient Photocatalytic CO2 Reduction

Metal halide perovskites have exhibited considerable potential for solar-driven photocatalytic CO 2 reduction, yet their practical application is largely hindered by lead toxicity and severe charge recombination. In this work, we report the synthesis and screening of lead-free halide double perovskite Cs 2 AgBiX 6 (CABX, X = Cl, Br, I) nanocrystals via an antisolvent technique, followed by the construction of Cs 2 AgBiX 6 @WS 2 (CABBWS) composites with varying WS 2 contents (25, 50, 75 mol%). Structural and interfacial characterizations confirm the intimate contact between CABB particles and WS 2 nanosheets, while photophysical and photoelectrochemical (PEC) analyses demonstrate the optimal CABBWS50 with superior charge separation properties. The CABB-WS 2 intimate interface enhances charge transport by reducing activation energy, as evidenced by temperature-dependent TRPL measurements. The optimal CABBWS50 achieves a CO evolution rate of 13.65 µmol g − 1 h − 1 under visible-light irradiation ( λ > 420 nm), approximately 3.7 times higher than pristine CABB. This work provides comprehensive insights into the design of high-performance lead-free perovskite photocatalysts via rational halogen engineering and interfacial regulation, offering a promising strategy for solar fuel production toward carbon neutrality.