Reduced water dissociation barrier on constructing Pt-Co/CoO_x interface for alkaline hydrogen evolution

Water dissociation process is generally regarded as the rate-limiting step for alkaline hydrogen evolution reaction (HER), and severely inhibits the catalytic efficiency of Pt based catalysts. To overcome this problem, the in-situ constructed interfaces of Pt-Co alloy and amorphous cobalt oxide (CoO_x) on the carbon powder are designed. The amorphous CoO_x at Pt-Co/CoO_x interfaces not only provide active sites for water dissociation to facilitate Volmer step, but also produce the strong electronic transfer with Pt-Co. Accordingly, the obtained interfacial catalysts exhibit outstanding alkaline HER performance with a Tafel slope of 29.3 mV·dec⁻¹ and an ultralow overpotential of only 28 mV at 10 mA·cm⁻². Density functional theory (DFT) reveals that the electronic accumulation on the interfacial Co atom in Pt-Co/CoO_x constructing the novel active site for water dissociation. Compared to the Pt-Co, all of the energy barriers for water adsorption, water dissociation and hydrogen adsorption/desorption are reduced in Pt-Co/CoO_x interfaces, suggesting a boosted HER kinetics for alkaline HER.