Competitive adsorption strategy for adsorbed intermediates boosting alkaline hydrogen evolution

Abstract

RuSe₂ has been considered an efficient alkaline hydrogen evolution reaction (HER) electrocatalyst due to its fast water dissociation kinetics and lower price. However, its strong affinity to the adsorbed active intermediates blocks the active sites, hence largely falling short of its full activity potential. Herein, we report a feasible competitive adsorption strategy by introducing oxyphilic molybdenum (Mo) species into RuSe₂ (Mo–RuSe₂) to regulate the strong interaction between the Ru sites and HER intermediates, enabling highly efficient alkaline HER performance. In situ experimental and theoretical calculation results reveal that the oxyphilic Mo tailoring for RuSe₂ can not only alleviate OH_ad blocking on the Ru sites by the competitive adsorption of OH_ad between the Ru and Mo sites, but also optimize the hydrogen adsorption Gibbs free energy, thus facilitating the OH_ad transfer and H₂ release process, both of which synergistically promote the regeneration of Ru active sites. The optimized Mo–RuSe₂ exhibits an overpotential at 10 mA cm⁻² as small as 27 mV and a low Tafel slope of 39 mV dec⁻¹, as well as remarkable long-term stability. This finding is expected to shed new light on developing highly efficient alkaline HER catalysts by regulating the adsorption strength between the active sites and intermediates.