Structural Evolution and Electrochemical Performance of Ni₁₂P₅-FeP Catalysts for Oxygen Evolution Reaction in Alkaline Water/Seawater

Low voltage driven overall water splitting remains a significant challenge for practical hydrogen production. The unique interface and interaction between different components in heterostructures endow them with extraordinary properties that are not achievable in single-component materials. In this study, we introduce the Ni₁₂P₅-FeP heterostructure as a catalyst for the oxygen evolution reaction (OER) to enable efficient overall water splitting. In 1 M KOH solution, the Ni₁₂P₅-FeP electrocatalysts required overpotentials of 246.2 mV for OER to deliver the current density of 100 mA cm^-2. This outstanding catalytic activity can be attributed to the well-defined heterointerfaces that effectively activate reaction intermediates, the high electrical conductivity of the phosphide components for rapid electron transfer, and the favorable structure that promotes efficient mass transport. Moreover, the Ni₁₂P₅-FeP electrocatalysts show great potential for practical applications as it maintains remarkable durability over 24 h of continuous operation in alkaline simulated seawater. These results suggest that Ni₁₂P₅-FeP could serve as a promising candidate for OER, particularly in practical applications like seawater electrolysis, where durability and low overpotential are crucial for sustainable hydrogen production.