H₃O⁺ assisted hydrogen spillover over Ru-Mo₂Ti₂C₃ for efficient alkaline hydrogen evolution

The limited supply capacity and high transport kinetic energy barrier of H* hinder the implementation of the alkaline hydrogen evolution reaction (HER). Constructing an H₃O⁺ environment can effectively enhance the concentration and diffusion kinetics of H*, thereby alleviating the associated limiting factors. Here we report a novel Ru nanoclusters supported by 2D Mo₂Ti₂C₃ nanosheets (Ru-Mo₂Ti₂C₃) as an effective HER electrocatalyst in alkaline environments. Results indicate that H* is rapidly generated at the Ru site due to the efficient water dissociation capability of Ru-Mo₂Ti₂C₃, subsequently combining with water molecules to form H₃O⁺. H₃O⁺ then rapidly diffuses to the -O group on MXene, which can release H* and act as active sites for H₂ evolution, facilitated by the lower migration energy barrier of H₃O⁺. This strategy simultaneously enhances both the supply and transfer of H*, facilitating synergistic catalysis between Ru and MXene. Consequently, Ru-Mo₂Ti₂C₃ exhibits an overpotential of 47 mV at 10 mA cm^-2, lower than that observed in acidic media (108 mV). This paper introduces a new approach for the development of catalytic materials aimed at achieving efficient and pH-universal electrochemical H₂ evolution.