Activating and Identifying the Active Site of RuS₂ for Alkaline Hydrogen Oxidation Electrocatalysis

Abstract

Searching for highly efficient and economical electrocatalysts for alkaline hydrogen oxidation reaction (HOR) is crucial for the development of the alkaline polymer membrane fuel cells (APMFCs). 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 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 demonstrates 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 adsorption 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.