Bimetallic NiO/NiFe₂O₄ heterostructures with interfacial effects for boosting electrochemical water splitting applications

The present work reports the simple preparation of NiO/ NiFe₂O₄ heterostructures with interfacial effects as bifunctional electrocatalysts for overall water splitting. At increasing Ni/Fe precursor ratios, the evolution of NiO phases is observed in NFO heterostructures, which incorporate differential strain effects at the interface. The modulated heterojunction of NiO/NiFe₂O₄ heterostructure incorporates compressive strain at the interfaces enhancing its electrocatalytic performances. Notably, NiO/NiFe₂O₄ heterostructure prepared at equimolar Ni/Fe ratios (NFO-1) exhibits significant electrocatalytic performances due to modulated interfacial effects. As such, NFO-1 exhibits lower OER and HER overpotentials of about 242 mV and 106 mV for 10 mA cm⁻² current density and exhibits improved water splitting activity, requiring 1.56 V to drive 10 mA cm⁻² current density. The present work emphasizes the importance of modulating the heterostructures of transition metal oxides to enhance the interfacial effects as bifunctional electrocatalysts for water splitting applications.