Heterostructure‐Induced Electronic Modulation Enables Spin‐Polarized Co Sites for Balanced OH−/Ethanol Adsorption in Efficient Ethanol Oxidation to Acetate

Abstract

Electrochemical ethanol oxidation to acetate enables energy‐saving hydrogen production with value‐added chemical generation. Cobalt‐based metal‐organic frameworks (MOFs) are promising ethanol oxidation reaction (EOR) electrocatalysts, but reconstructed Co3+ centers often bind OH− too strongly, causing active‐site blocking and limited ethanol adsorption. Here, we construct a hierarchical NiS@Co‐ZIF‐L heterostructure on nickel foam through sequential in situ growth to modulate reconstructed Co sites. In situ Raman spectroscopy shows that interfacial NiS coupling lowers the onset potential for CoOOH reconstruction. DFT calculations indicate geometric perturbation of the Co‐related coordination environment, while Co K‐edge XAFS, EPR spectroscopy, and SQUID magnetometry support modified Co electronic structure and enhanced spin polarization consistent with high‐spin Co‐related sites. This electronic/spin modulation shifts the d‐band center from −1.19 to −2.13 eV, moderates OH− binding, and reduces the computed C–H activation barrier from 1.39 to 0.55 eV. MD simulations suggest a more balanced interfacial OH−/ethanol distribution, consistent with potentially alleviated hydroxide‐related site blocking. The optimized catalyst reaches 10 mA cm−2 at 1.29 V vs. RHE with 96.67% Faradaic efficiency and sustains 1 A cm−2 for 500 h in an AEM electrolyzer, with an acetate‐production energy consumption of 4.02 kWh kg−1.