Correlating Alkaline Hydrogen Electrocatalysis and Hydroxide Binding Energies on Mo-Modified Ru Catalysts

Exploring efficient electrocatalysts applied for the hydrogen oxidation reaction (HOR) and the hydrogen evolution reaction (HER) under alkaline electrolytes and fundamentally understanding the corresponding reaction mechanisms are crucial to realizing the reversible conversion of hydrogen energy. Much work has been devoted to boosting alkaline HOR/HER performances by promoting the hydroxide binding energy (OHBE) but little on understanding the correlation between them. Herein, the synthesis of Mo-modified Ru catalysts with an almost identical hydrogen binding energy (HBE) is reported, and the structure–activity correlation during the HOR/HER is studied. By combining experimental data and theoretical calculations, a volcano-type relationship of HOR/HER performance with OHBE values is provided. Density functional theory (DFT) further reveals that the optimal OHBE, together with the decreased reaction energy barrier for water formation/dissociation, contributes to remarkable alkaline HOR/HER performance.