Lead‐Free Cs2AgBiBr6 Nanocrystals Confined in MCM‐48 Mesoporous Molecular Sieve for Efficient Photocatalytic CO2 Reduction

Exploring highly efficient and stable halide perovskite‐based materials for photocatalytic CO2 reduction is a great challenge due to their poor intrinsic instability. Coincidentally, mesoporous molecular sieves have received tremendous attention as adsorbents, catalysts, and catalyst carriers. Herein, lead‐free double perovskite of Cs2AgBiBr6 (CABB) nanocrystals are grown in situ in MCM‐48 mesoporous molecular sieve for photocatalytic CO2 reduction. A remarkable performance is achieved by the CABB@MCM‐48 composite, which far exceeds that of pristine CABB. The mechanism of the photocatalytic CO2 reduction reaction is systematically investigated by the combination of in situ diffuse reflectance infrared Fourier transform spectra and density functional theory calculations. The result indicates that the molecular sieve can not only enhance the adsorption of CO2 molecules, but also promote the CO2 activation by reducing the energy barriers. This study provides some new insights into the design of excellent perovskite/molecular sieve‐based catalysts for solar fuel applications. A CABB@MCM‐48 composite is constructed by in situ growth of lead‐free double perovskite of Cs2AgBiBr6 (CABB) nanocrystals in MCM‐48 mesoporous molecular sieve. Owing to the improved CO2 adsorption capacity, efficient charge separation, and abundant active sites, the developed CABB@MCM‐48 composite exhibits significantly enhanced photocatalytic performance for CO2 reduction than the pristine CABB counterpart.