Searching for highly efficient and economical electrocatalysts for alkaline hydrogen oxidation reaction (HOR) is crucial for the development of alkaline polymer membrane fuel cells. Here, we report a valid strategy to active pyrite-type RuS2 for alkaline HOR electrocatalysis by introducing sulfur vacancies. The obtained S-vacancies modified RuS2-x exhibits outperformed HOR activity with a current density of 0.676 mA cm-2 and mass activity of 1.43 mA μg-1, which are 15-fold and 40-fold improvement than those of Ru catalyst. In situ Raman spectra demonstrate the formation of S-H bond during the HOR process, identifying the S atom of RuS2-x is the real active site for HOR catalysis. Density functional theory calculations and experimental results including in situ surface-enhanced infrared absorption spectroscopy suggest the introduction of S vacancies can rationally modify the p orbital of S atoms, leading to enhanced binding strength between the S sites and H atoms on the surface of RuS2-x, together with the promoted connectivity of hydrogen-bonding network and lowered water formation energy, contributes to the enhanced HOR performance.
Keywords: Hydrogen Oxidation Reaction; in situ Raman; in situ surface-enhanced infrared absorption spectroscopy; transitional metal sulfides.
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