Strong Dipole Moments from Ferrocene Methanol Clusters Boost Exciton Dissociation in Quantum-Confined Perovskite for CO₂ Photoreduction.

Abstract

Perovskite nanocrystals (PCNs) exhibit a significant quantum confinement effect that enhances multiexciton generation, making them promising for photocatalytic CO₂ reduction. However, their conversion efficiency is hindered by poor exciton dissociation. To address this, we synthesized ferrocene-methanol-functionalized CsPbBr₃ (CPB/FcMeOH) using a ligand engineering approach. By manipulating the electronic coupling between ligands and the PCN surface, facilitated by the increased dipole moment from hydrogen bonding in FcMeOH molecules, we effectively controlled exciton dissociation and interfacial charge transfer. Under 5 h of irradiation, the CO yield of CPB/FcMeOH reached 772.79 μmol g^-1, 4.95 times higher than pristine CPB. This high activity is due to the formation of hydrogen-bonded FcMeOH clusters on the CPB surface. The nonpolar disruption and strong dipole moment of FcMeOH molecules enhance electronic coupling between the FcMeOH ligands and the CPB surface, reducing the surface barrier energy. Consequently, exciton dissociation and interfacial charge transfer are promoted, efficiently utilizing multiple excitons in quantum-confined domains. Transient absorption spectroscopy confirms that CPB/FcMeOH exhibits optimized exciton behavior with fast internal relaxation, trapping, and a short recombination time, allowing photogenerated charges to more rapidly participate in CO₂ reduction.