Co2+ regulation enhances the surface adsorption activity of Ni2P to achieve efficient oxygen evolution

To circumvent the cost constraints and scarcity of noble-metal oxygen evolution reaction (OER) catalysts, this work pioneers an electrolyte-regulation strategy for boosting nickel phosphide (Ni 2 P) performance. Introducing a trace amount of Co 2+ (40 µL 1.0 M CoSO 4 ) into the alkaline KOH electrolyte significantly enhances the surface adsorption kinetics and reactivity of Ni 2 P. The optimized system achieves a reduction in overpotential to 363.9 mV, a decrease in Tafel slope to 109.6 mV dec −1 , and a smaller charge transfer resistance. Mechanism research reveals that a dynamic "oxidation-adsorption-reconstruction" process is driven by electrical oxidation. Specifically, Co 2+ undergoes an oxidation reaction and is adsorbed on the material surface, leading to the in-situ formation of an epitaxial CoOOH/NiOOH heterointerface. This simultaneously increases active-site density, optimizes OH* adsorption energy, and accelerates interfacial electron transfer. This electrolyte-catalyst synergy strategy redefines efficient OER electrocatalyst design, shifting focus from complex material engineering to intelligent interfacial microenvironment control. To address sluggish OER kinetics, this study develops an electrolyte regulation strategy using trace Co 2+ to enhance Ni 2 P electrocatalysts. The in-situ formed CoOOH/NiOOH heterointerface optimizes adsorption and electron transfer, lowering overpotential and improving kinetics, offering an efficient alternative to noble-metal catalysts. • Electrolyte engineering with trace Co 2+ enhances Ni 2 P via in-situ interface reconstruction and optimized adsorption. • Achieves efficient OER with favorable kinetics and exceptional 110-hour stability. • Offers a universal, cost-effective strategy for non-precious electrocatalysts via electrolyte regulation.