Facets and Defects in Perovskite Nanocrystals for Photocatalytic CO₂ Reduction

Light-emitting lead halide perovskite nanocrystals are typically obtained in a six-faceted cube shape. However, for applications such as catalysis, more active facets for the adsorption/desorption of reactants/products and the suppression of carrier recombination are essentially required. To meet these challenges, herein CsPbBr₃ perovskite nanocrystals in cube and faceted noncube shapes were explored for photocatalytic reductions of CO₂. Importantly, halide-deficient dim multifaceted noncube emitters having less than 1% photoluminescence quantum yields showed superior catalytic activity compared to that of bright halide-rich cube nanocrystals. Beyond these, hexapod-shaped nanocrystals were also explored, and these remained in an intermediate state. With the support of density functional theory, the adsorption and desorption probabilities of reactants/products on different facets were also calculated and correlated with experimental findings. These results indicated that facets and defects of perovskite nanocrystals are equally important for carrying out catalytic reactions.