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

Metal halide perovskites have exhibited considerable potential for solar-driven photocatalytic CO₂ 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 Cs₂AgBiX₆ (CABX, X = Cl, Br, I) nanocrystals via an antisolvent technique, followed by the construction of Cs₂AgBiX₆@WS₂ (CABBWS) composites with varying WS₂ contents (25, 50, 75 mol%). Structural and interfacial characterizations confirm the intimate contact between CABB particles and WS₂ nanosheets, while photophysical and photoelectrochemical (PEC) analyses demonstrate the optimal CABBWS50 with superior charge separation properties. The CABB-WS₂ 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.