Ligand-mediated exciton dissociation and interparticle energy transfer on CsPbBr3 perovskite quantum dots for efficient CO2-to-CO photoreduction

Abstract

Perovskite quantum dots (PQDs) hold immense potential as photocatalysts for CO₂ reduction due to their remarkable quantum properties, which facilitates the generation of multiple excitons, providing the necessary high-energy electrons for CO₂ photoreduction. However, harnessing multi-excitons in PQDs for superior photocatalysis remains challenging, as achieving the concurrent dissociation of excitons and interparticle energy transfer proves elusive. This study introduces a ligand density-controlled strategy to enhance both exciton dissociation and interparticle energy transfer in CsPbBr₃ PQDs. Optimized CsPbBr₃ PQDs with the regulated ligand density exhibit efficient photocatalytic conversion of CO₂ to CO, achieving a 2.26-fold improvement over unoptimized counterparts while maintaining chemical integrity. Multiple analytical techniques, including Kelvin probe force microscopy, temperature-dependent photoluminescence, femtosecond transient absorption spectroscopy, and density functional theory calculations, collectively affirm that the proper ligand termination promotes the charge separation and the interparticle transfer through ligand-mediated interfacial electron coupling and electronic interactions. This work reveals ligand density-dependent variations in the gas-solid photocatalytic CO₂ reduction performance of CsPbBr₃ PQDs, underscoring the importance of ligand engineering for enhancing quantum dot photocatalysis.

Keywords: Electronic coupling; Exciton dissociation; Ligands; Perovskite quantum dots; Photocatalytic CO(2) reduction.