Tailoring Spin‐Polarized Ferrimagnetic Domains in CeCu‐Fe3O4 Breaks the Adsorption‐Activation Dilemma in Biomass Valorization

Abstract

Achieving efficient electro‐oxidation of 5‐hydroxymethylfurfural (HMF) to high‐value chemicals such as 2,5‐furandicarboxylic acid (FDCA) remains highly challenging because of the difficulty in simultaneously optimizing HMF adsorption and lowering the activation barrier for the rate‐determining aldehyde‐to‐carboxylate conversion. Herein, we exhibit a spin‐engineered Ce and Cu co‐doped inverse spinel iron oxide (CeCu‐Fe3O4) featuring regulated electronic structure, abundant oxygen vacancies, and tunable ferrimagnetic spin polarization. The catalyst achieves 97.6% HMF conversion, 98.3% FDCA selectivity, and 98.2% Faradaic efficiency with sustained 100 h stability in the HMF electro‐oxidation process, outperforming most reported non‐noble‐metal electrocatalysts. Through systematic experimental characterization and theoretical calculations, we reveal that Ce/Cu co‐doping induces a coordinated reconstruction of the electronic and magnetic landscape in Fe3O4, manifested by enhanced spin‐dependent electronic polarization and the formation of oxygen‐vacancy‐associated unpaired electron centers that strongly couple with Fe d orbitals. This coupled electronic and magnetic reconstruction modulates the interfacial interaction between the catalyst surface and HMF molecules, thereby regulating adsorption behavior and facilitating subsequent charge‐transfer processes. This work highlights that tailoring spin‐polarized magnetic domains through Ce/Cu co‐doping effectively overcomes the adsorption‐activation bottleneck in HMF electro‐oxidation, providing a targeted strategy for designing state‐of‐the‐art electrocatalysts for biomass valorization.