Engineering Asymmetric Active Sites with Spin Polarization for Selective Photocatalytic CO₂-to-CH₃COOH Conversion.

Abstract

Selective photocatalytic reduction of CO₂ to CH₃COOH is highly desirable but hindered by poor intermediate stabilization and sluggish C-C coupling. Here we report a coordination-environment engineering strategy to construct asymmetric Co active sites and induce intrinsic spin polarization by nitrogen incorporation into Co₃O₄. Nitrogen substitution and oxygen vacancy formation generate Co sites with distinct coordination and charge distributions, stabilizing *CO intermediates and lowering the C-C coupling barrier. Concurrently, spin polarization enhances charge carrier separation, further intensified by an external magnetic field. <i>In situ</i> spectroscopy and theoretical calculations confirm the synergistic role of asymmetry and spin effects in facilitating intermediate formation and CH₃COOH production. The optimized N-Co₃O_4-<i>_X</i> catalyst achieves a CH₃COOH yield of 41.4 μmol g^-1 h^-1 with 95% electron selectivity under external magnetic field. This work presents a dual-modulation strategy for efficient CO₂-to-C₂ conversion.