Interface engineered NiFe₂O₄−x/NiMoO₄ nanowire arrays for electrochemical oxygen evolution

Abstract

Designing highly active and stable electrocatalysts for oxygen evolution reaction (OER) is the key to success in sustainable water splitting reaction, a sustainable route towards high purity hydrogen production. Interface engineering is one of the most effective strategies for modulating the local electronic structure of active sites to enhance catalytic activity. Herein, NiFe₂O₄−x nanoparticles were integrated to NiMoO₄ nanowires (NiFe₂O₄−x/NMO) grown on nickel foam to construct an extended interface with strong electronic interactions. The NiFe₂O₄−x/NMO demonstrates high OER activities as manifested by a low overpotential of 326 mV at a high current density of 600 mA cm⁻² and good long-term stability. The intimate interface between NiFe₂O₄−x and NiMoO4 is responsible for the Fe-facilitated phase transition to active γ-NiOOH phase as revealed by in situ Raman spectroelectrochemical studies. This study outlines how the interface design of integrated nanostructures can optimize the formation of active phase for enhanced catalytic activity.