Revealing interfacial charge redistribution of homologous Ru-RuS2 heterostructure toward robust hydrogen oxidation reaction

Abstract

Precisely tailoring the surface electronic structures of electrocatalysts for optimal hydrogen binding energy and hydroxide binding energy is vital to improve the sluggish kinetics of hydrogen oxidation reaction (HOR). Herein, we employ a partial desulfurization strategy to construct a homologous Ru-RuS2 heterostructure anchored on hollow mesoporous carbon nanospheres (Ru-RuS2@C). The disparate work functions of the heterostructure contribute to the spontaneous formation of a unique built-in electric field, accelerating charge transfer and boosting conductivity of electrocatalyst. Consequently, Ru-RuS2@C exhibits robust HOR electrocatalytic activity, achieving an exchange current density and mass activity as high as 3.56 mA cm−2 and 2.13 mA μgRu-1, respectively, exceeding those of state-of-the-art Pt/C and most contemporary Ru-based HOR electrocatalysts. Surprisingly, Ru-RuS2@C can tolerate 1000 ppm of CO that lacks in Pt/C. Comprehensive analysis reveals that the directional electron transfer across Ru-RuS2 heterointerface induces local charge redistribution in interfacial region, which optimizes and balances the adsorption energies of H and OH species, as well as lowers the energy barrier for water formation, thereby promoting the HOR performance.