Oxidation state of nickel in alloy to modulate the microenvironment of platinum surface for hydrogen evolution reaction

Platinum-based catalysts are the best HER catalysts, but their high price affects their mass application, so how to reduce the amount of platinum in catalysts has become a hot research topic. Herein, we synthesized low platinum dosage and highly dispersed nano-alloy catalyst PtNi/CB using a one-step solvothermal approach. Characterization shows that in the PtNi/CB catalyst, nickel element mainly exists in the form of oxidation state and promotes the dissociation of water molecules, resulting in the formation of a hydrogen-rich chemical microenvironment on the catalyst surface, while platinum element mainly exists in the form of metal state, electron flow from nickel to platinum forms an electron-rich platinum structure with high proton affinity, which can well regulate the adsorption/desorption energies of intermediate H*. The combined effect of platinum and nickel enhances catalyst performance and stability. Based on this, the PtNi/CB catalyst requires only 29 mV overpotential to achieve a current density of 10 mA cm−2 in 1 M KOH, which is much better than that of commercial Pt/C catalyst (49 mV), and can be operated stably for a long time.