Spin-Polarized Interfaces Redirect CO₂ Reduction From CO to Formate

Achieving high product selectivity in electrocatalytic carbon dioxide reduction (CO₂RR) remains a critical challenge due to competition between multiple proton-coupled electron-transfer pathways on catalyst surfaces. Meanwhile, chirality-induced spin selectivity (CISS), which enables spin-polarized electron transport through chiral interfaces, has recently emerged as a promising strategy to modulate interfacial electrochemical reactions. Although the CISS effect has been shown to enhance selectivity and efficiency in the spin-sensitive oxygen evolution reaction (OER), its role in regulating CO₂RR pathways and in stabilizing intermediates remains largely unexplored. Here, chiral molecules (R- and S-1,1'-bi-2-naphthyl-2,2'-diyl hydrogen phosphate, BNP) were integrated with SnO₂ to construct chiral-modified catalysts (R-BNP/SnO₂ and S-BNP/SnO₂). Compared with bare SnO₂ and racemic BNP-modified SnO₂ (Rac-BNP/SnO₂), the chiral catalysts exhibited a pronounced shift in product selectivity from CO toward formate production. Importantly, in-situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) reveals that the chiral interface selectively stabilizes the O-bound *OCHO intermediate associated with the formate pathway and modulates interfacial water structure and hydrogen-bonding dynamics. These findings demonstrate that spin-polarized interfacial electron transfer can regulate CO₂RR pathway selectivity by modulating the stabilization of key intermediates. More broadly, this work establishes chiral spin-selective interfaces as a new strategy for regulating competitive electrocatalytic reaction pathways.