Unlocking Spatially Constrained Photogenerated Charge via Dimension Regulation in Metal Halide Perovskite Nanowires for Enhanced Photocatalytic CO2 Reduction

Metal halide perovskite quantum dots, renowned for their unique photoelectrical properties, offer exciting prospects for photocatalytic carbon dioxide reduction. However, drawbacks arise from the adverse effects of excessive spatial confinement, resulting in excessive charge carrier recombination. In this work, an effective strategy dependent on dimensional regulation was proposed for enhancing the separation and transport of charge carrier. This is achieved by judiciously releasing one dimension in the all-dimensionally confined quantum dot. The approach is exemplified through a case study involving zero-dimensional CsPbBr3 quantum dots and one-dimensional nanowires with tunable axial lengths. A thorough study employing femtosecond transient absorption spectroscopy discloses the photophysical properties and carrier dynamics of the catalysts and unveils key factors that bolster performance. Especially, the relaxation of confinement effects of the nanowires in the axial dimension promotes carrier separation efficiency. Moreover, the introduction of long-range trapping processes facilitates the attainment of a significant charge-separated state and a higher transfer efficiency. Consequently, the nanowires with optimal length demonstrate remarkable photocatalytic CO2 reduction activity that is approximately seven times higher than that of the zero-dimensional counterpart, achieving a CO productivity of around 88 μmol·g–1·h–1 and 100% selectivity. This work demonstrates the importance of precise dimensional control for low-dimensional nanomaterials in photocatalytic reactions.