Morphology-defect synergy in Cs2PdBr6 perovskite nanocrystals for enhanced photocatalytic CO2-to-CO conversion

Designing efficient photocatalysts for the selective conversion of CO 2 to CO is crucial for addressing energy and environmental challenges. Lead-free Cs 2 PdBr 6 perovskite shows promise but suffers from uncontrolled morphology and surface defects. Herein, we propose an antisolvent-assisted recrystallization (ASAR) strategy to synergistically regulate the morphology, defect microenvironment, and surface redox states of Cs 2 PdBr 6 nanocrystals (NCs). Using propionic acid (PA) as the antisolvent, PA-Cs 2 PdBr 6 NCs exhibit reduced particle size, optimized Br vacancies, and tailored surface chemistry. The modifications enhance photogenerated carrier separation efficiency and band alignment, achieving a remarkable CO production rate of 198.9 μmol g −1 h −1 with 98.8% selectivity. In situ spectroscopic analysis, XAFS techniques and DFT calculations was employed to reveal the reaction pathway and the mechanism for CO 2 activation of PA-Cs 2 PdBr 6 NCs in the photocatalytic process. This work establishes a universal strategy for coupled optimization of perovskite photocatalysts’ morphology and electronic states.