Colloidal-nanoparticle-derived nickel/ferric oxide heterointerfaces for promoting the alkaline oxygen evolution reaction

Abstract

Heterointerface engineering is an effective strategy to enhance electrocatalytic activity for water splitting by binding two different materials. Specifically, it offers prospects in creating viable transition-metal-based anode materials for catalyzing the oxygen evolution reaction (OER). However, despite its promise, metal/metal oxide heterointerface engineering has not been comprehensively explored for maximizing the electrocatalytic performance, that is, for minimizing the OER overpotential and maintaining the physicochemical characteristics of the catalyst during operation. Therefore, to resolve these issues, the present study was aimed at synthesizing colloidal nanoparticles (NPs) in mixed form at various Ni/Fe ratios (100 : 0 to 0 : 100) to create heterointerfaces between metallic Ni and Fe₂O₃ NPs. Among the prepared NPs, the 75 : 25 sample annealed under H₂/Ar atmosphere recorded the highest alkaline water oxidation activity (199 mV at 10 mA cm⁻²) with long-term durability for five days, indicating that the 75 : 25 ratio was the optimal composition for generating abundant Ni/Fe₂O₃ heterointerfaces. The practical applicability of the 75 : 25 sample was confirmed by its remarkable performance as an anode catalyst for an anion exchange membrane water electrolyzer (AEMWE). The outstanding electrocatalytic performance of the 75 : 25 specimen was induced not only by the interparticle interactions between Ni and Fe₂O₃ NPs, but also by the intraparticle interactions within the heterostructured NPs. Overall, this report illustrates the benefits of Ni/Fe₂O₃ heterointerface engineering in obtaining highly efficient anode catalysts for AEMWEs.