Amine‐Mediated In Situ Oxygen Vacancy Generation in SnO 2 Nanocrystals for Selective CO 2 Photoreduction

Photocatalytic CO 2 reduction over tin dioxide (SnO 2 ) is promising for solar‐to‐chemical conversion, yet its efficiency is hindered by rapid charge recombination and sluggish surface reaction kinetics. Here, we develop an amine‐mediated in situ oxygen‐vacancy generation strategy, in which amine‐functionalized carbon nanotubes regulate SnO 2 crystallization to construct oxygen‐vacancy‐rich SnO 2 nanocrystals with strongly coupled SnO 2 /CNT interfaces. The interfacial amine groups coordinate with Sn precursors during growth, promoting oxygen vacancy formation while enhancing interfacial coupling and CO 2 adsorption through Lewis acid–base interactions. The generated oxygen vacancies modulate the local electronic structure, facilitate interfacial charge transfer, and regulate surface reaction pathways. The optimized OV‐SnO 2 @NCNT catalyst achieves a CO yield of 174.8 µmol g −1 , approximately 4.0 times higher than that of SnO 2 @OCNT, with a high CO selectivity of 82.9%. Spectroscopic and electrochemical analyses reveal enhanced charge separation and carrier utilization efficiency enabled by the oxygen‐vacancy‐rich SnO 2 /CNT interface. Combined in situ FT‐IR measurements and density functional theory calculations demonstrate that oxygen vacancies promote CO 2 activation, stabilize key CO 2 ‐derived intermediates, and facilitate selective CO generation by regulating intermediate adsorption behavior. This work provides an interface‐directed defect‐engineering strategy for controllable oxygen vacancy construction and rational regulation of reaction pathways toward selective solar‐driven CO 2 conversion.