Spin‐Polarization in Rigid/Soft Layered Oxide Catalyst Regulates Key Intermediates for Efficient CO ₂ ‐to‐Formate Conversion

Abstract

Abstract Precise control of metal oxidation states is pivotal in regulating the adsorption energetics of *OCHO intermediate during CO 2 electroreduction. However, the stabilization of oxidation states to enable effective intermediate adsorption–desorption behavior remains a critical challenge for enhancing formate yield. Herein, we synthesize a rigid/soft layered oxides (CuInAlO 4 ) with rigid Al–O framework and soft Cu–O active units. Spin‐polarized electrons derived from the unpaired electrons in the dz 2 orbital of CuO 5 units transfer to the empty 5s/5p orbitals of In 3 ⁺ via the superexchange interaction of 3d(Cu) − 2p(O) − 5s/5p(In). The enhanced spin polarization promotes spin‐orbit coupling between metal sites (Cu, In) and *OCHO intermediates (O), forming In─*O─CH─O*─Cu electronic bridge and greatly improving the formation efficiency of formate. CuInAlO 4 catalyst achieves exceptional formate selectivity (faradaic efficiency of 95% at 500 mA cm −2 , energy efficiency of 80.3%, overpotential of 180 mV), outperforming conventional In─O*─CH─O*─In pathways by reducing the *OCHO‐to‐HCOOH energy barrier by 1.31 eV. Experimental and theoretical analyses reveal that the rigid AlO 5 units stabilize metal‐oxygen bonds, preventing oxygen dissolution, while accelerating formate production kinetics through spin‐polarized charge transfer.