Sluggish reaction kinetics of Pt catalysts for the hydrogen evolution reaction (HER) in alkaline media remains a challenge in water-alkali electrolyzers, which originates from a water dissociation step involved in the alkaline HER. In this talk, we present our efforts towards promoting the alkaline HER activity of Pt catalysts by using mesoporous α-MoC1-x (MMC) as the catalyst support. In the Pt/MMC catalyst, α-MoC1-x phase enables enhanced water dissociation capability while the mesoporous structure endows high surface area and efficient mass transport. In addition, the electronic metal-support interaction (EMSI) between Pt NPs and MMC results in an electron transfer from MMC to Pt NPs adjusting the binding energy of proton on the Pt NPs to an optimized level. As a result, the Pt/MMC catalyst exhibited 1.6- and 1.5-fold higher mass and specific activity than commercial Pt/C with the same Pt loading.