Engineering Interfacial Electronic Polarization in Pt@S–Co ₃ O _{4– <i>x</i>} for Superior Glycerol-Assisted Water Electrolysis

Rational modulation of the metal-oxide interface is recognized as an effective strategy for optimizing the electronic structure and catalytic performance of catalysts. Herein, using oxygen-deficient Co3O4–x nanowire arrays as a model, we demonstrate that S-doping combined with Pt modification can effectively tune the interfacial electronic interactions in Pt@S–Co3O4–x, resulting in a polarized electronic state characterized by an electron-deficient S–Co3O4–x substrate and electron-enriched Pt species. This configuration endows Pt@S–Co3O4–x with outstanding performance in glycerol-assisted water electrolysis. Specifically, a membrane electrode assembly (MEA) electrolyzer incorporating the Pt@S–Co3O4–x catalyst achieves a current density of 100 mA cm–2 at a low voltage of 1.50 V, exhibits nearly 100% Faradaic efficiency (FE) for hydrogen evolution at the cathode, and demonstrates a high formate FE of 95.0% with a notable formate production rate of 88.5 mg h–1 cm–2 at the anode, along with excellent operational stability. Theoretical calculations further confirm that S doping enhances electronic polarization at the interface in Pt@S–Co3O4–x, facilitating H2O adsorption and activation, and promoting the conversion of hydrogen intermediates into H2.