In Situ Growth of Lead-Free Cs2CuBr4 Perovskite Quantum Dots in KIT-6 Mesoporous Molecular Sieve for CO2 Adsorption, Activation, and Reduction

Metal halide perovskites (MHPs) areemerging as promisingcandidatesfor photocatalytic CO2 conversion. However, their practicalapplication is still restricted by the poor intrinsic stability andweak adsorption/activation toward CO2 molecules. The rationaldesign of MHPs-based heterostructures with high stability and abundantactive sites is a potential solution to this obstacle. Herein, wereport the in situ growth of lead-free Cs2CuBr4 perovskite quantum dots (PQDs) in KIT-6 mesoporous molecular sieve,obtaining remarkable photocatalytic CO2 reduction activityand durable stability. The optimized Cs2CuBr4@KIT-6 heterostructure exhibits the photocatalytic CO and CH4 evolution rates of 51.6 and 17.2 mu mol g(-1) h(-1), respectively, far exceeding those of pristineCs(2)CuBr(4). On the basis of in situ diffuse reflectanceinfrared Fourier transform spectra and theoretical investigations,the detailed CO2 photoreduction pathway is systematicallyrevealed. This work provides a new route for the rational constructionof perovskite-based heterostructures with strong CO2 adsorption/activationand good stability for photocatalytic CO2 reduction. The in situ growth of lead-free Cs2CuBr4 perovskite quantum dots in KIT-6 mesoporousmolecular sieve wasrealized, obtaining a Cs2CuBr4@KIT-6 heterostructurewith remarkable photocatalytic CO2 reduction activity anddurable stability. The KIT-6 molecular sieve played dual roles infacilitating the CO2 adsorption and promoting CO2 activation, which led to the enhanced photocatalytic performance.