In Situ Growth of Lead-Free Cs 2 CuBr 4 Perovskite Quantum Dots in KIT-6 Mesoporous Molecular Sieve for CO 2 Adsorption, Activation, and Reduction.

Metal halide perovskites (MHPs) are emerging as promising candidates for photocatalytic CO 2 conversion. However, their practical application is still restricted by the poor intrinsic stability and weak adsorption/activation toward CO 2 molecules. The rational design of MHPs-based heterostructures with high stability and abundant active sites is a potential solution to this obstacle. Herein, we report the in situ growth of lead-free Cs 2 CuBr 4 perovskite quantum dots (PQDs) in KIT-6 mesoporous molecular sieve, obtaining remarkable photocatalytic CO 2 reduction activity and durable stability. The optimized Cs 2 CuBr 4 @KIT-6 heterostructure exhibits the photocatalytic CO and CH 4 evolution rates of 51.6 and 17.2 μmol g -1 h -1 , respectively, far exceeding those of pristine Cs 2 CuBr 4 . On the basis of in situ diffuse reflectance infrared Fourier transform spectra and theoretical investigations, the detailed CO 2 photoreduction pathway is systematically revealed. This work provides a new route for the rational construction of perovskite-based heterostructures with strong CO 2 adsorption/activation and good stability for photocatalytic CO 2 reduction.