Perovskite–Molecular Photocatalyst Synergy and Surface Engineering for Superior Photocatalytic Performance

Metal halide perovskite nanocrystals (NCs), known for their strong visible-light absorption and tunable optoelectronic properties, show significant promise for photocatalytic applications. However, their efficiency is often hindered by rapid charge recombination and insufficient exciton dissociation, limiting effective catalysis. Excited-state interactions at the NC interface are critical in determining photocatalytic performance, underscoring the need for strategies that enhance charge separation and minimize recombination. To address these challenges, we developed a composite material by combining cesium lead bromide (CsPbBr₃) nanocrystals with ferrocene carboxylic acid (FcA), a hole-extracting moiety. This integration enhances exciton dissociation through energy level alignment and recombination suppression, resulting in a 3-fold increase in the photocatalytic oxidation yield of benzylamine to <i>N</i>-benzylidenebenzylamine (35 ± 5% versus 12 ± 2% for pristine CsPbBr₃). Additionally, thionyl bromide (SOBr₂) surface modification strips off ligands and introduces bromide ions onto the CsPbBr₃ NCs, further improving charge transfer and substrate accessibility, resulting in a 27 ± 5% yield within 3 h. While SOBr₂ treatment enhances initial catalytic performance, its acidic nature may lead to reversible reactions and side products over extended reaction times. This study highlights the impact of molecular integration and surface engineering on optimizing interfacial charge dynamics, providing a pathway toward robust, high-efficiency perovskite photocatalysts for sustainable chemical transformations.