Spin‐State Engineering of Co ³⁺ for Optimized Interfacial Microenvironment and Enhanced Glycerol Electrooxidation

Abstract Engineering the electronic structure of transition metal catalysts is very important for regulating electrocatalytic reactions yet remains challenging, particularly in modulating the spin state for biomass valorization. Herein, a novel spin‐state engineering strategy is proposed to dramatically enhance the glycerol oxidation reaction (GOR) for selective formate production. It is demonstrated that vanadium (V) doping‐induced lattice distortion in Co ₃ O ₄ triggers a pivotal low‐spin to high‐spin (t _2g ⁴ e _g ² ) transition of Co ³⁺ ions. Through a combination of in situ spectroscopic techniques and theoretical calculations, it is revealed that this high‐spin state effectively tailors the interfacial microenvironment by reducing the population of strongly hydrogen‐bonded water molecules (≈30%) and concurrently strengthens the adsorption of glycerol and key intermediates (e.g., glyceric acid, glycolic acid), thereby optimizing the reaction pathway. As a result, the optimized high‐spin V‐Co ₃ O ₄ catalyst achieves an exceptionally low overpotential (reduced by 70–150 mV across the range of 10 – 300 mA cm ⁻² ) and a remarkable format selectivity of 93%, significantly outperforming its low‐spin counterpart (57%). This work not only provides profound atomic‐level insights into the spin‐state‐dependent reaction mechanism but also establishes spin‐state control as a fundamental and powerful paradigm for designing advanced electrocatalysts for sustainable energy conversion.