Sulfur-doped manganese-cobalt hydroxide with promoted surface reconstruction for glycerol electrooxidation assisted hydrogen production

Glycerol electrooxidation reaction (GOR), as an attractive alternative to oxygen evolution reaction, not only produces value-added formic acid but also facilitates H₂ production. However, its practical application suffers from the lack of efficient electrocatalysts with high activity at low potentials. Herein, sulfur doped manganese-cobalt hydroxide nanosheets on nickel foam (Mn-Co-S/NF) has been demonstrated as a promising electrocatalytic electrode for GOR, showing high current density at low potentials and high Faradaic efficiency for formate production. The combination of ex situ characterization, operando Raman analysis, and in situ electrochemical impedance spectroscopy measurement unveils that S doping leads to the formation of hierarchically porous structure with abundant oxygen vacancies during the reaction, enabling the surface reconstruction to proceed in an easier manner and to a higher degree. As a result, the reconstructed Mn-Co-S/NF possesses highly enhanced charge/mass transfer capability and enriched high valence Co active species. Impressively, in a practical flow electrolyzer, an industrial-level current density of 900 mA cm⁻² can be achieved at a cell voltage of 2.0 V. It also exhibits H₂ yield rate of 3.5 mmol cm⁻² h⁻¹ at 200 mA cm⁻², realizing up to 30.2% energy saving efficiency compared to water electrolysis.