Abstract: AbstractIn the pursuit of sustainable energy solutions, the efficiency of the hydrogen evolution reaction (HER) in alkaline conditions has been a significant challenge, primarily due to the sluggish dissociation of water molecules on platinum (Pt) catalysts. Addressing this critical issue, our study introduces an innovative Pt-Co@NCS catalyst. This catalyst synergistically combines Pt nanoparticles with Co single atoms on a nitrogen-doped carbon scaffold, overcoming the traditional bottleneck of slow water dissociation. Its unique porous concave structure and nitrogen-enriched surface not only provide abundant anchoring sites for Co atoms but also create a conducive hydrophilic environment around the Pt particles. This design leads to a drastic improvement in the water dissociation process, as demonstrated by CO stripping and deuterium labeling experiments. Achieving an outstanding current density of 162.8 mA cm^-2 at -0.1 V versus RHE, a Tafel slope of 26.2 mV dec^-1, and a superior nominal mass activity of 15.75 mA μg_Pt^-1, the Pt-Co@NCS catalyst represents a significant step forward in enhancing alkaline HER efficiency, indicating promising advancements in the field.