2D NiFe ₂ O ₄ /Ni(OH) ₂ Heterostructure‐Based Self‐Supporting Electrode With Synergistic Surface/Interfacial Engineering for Efficient Water Electrooxidation

To meet the industrial demand for overall water splitting, oxygen evolution reaction (OER) electrocatalysts with low-cost, highly effective, and durable properties are urgently required. Herein, a facile confined strategy is utilized to construct 2D NiFe₂O₄/Ni(OH)₂ heterostructures-based self-supporting electrode with surface-interfacial coengineering, in which abundant and ultrastable interfaces are developed. Under the high molar ratio of Ni/Fe, both spinel oxide and hydroxides phases are formed simultaneously to obtain 2D NiFe₂O₄/Ni(OH)₂ heterostructure. The in-depth analysis indicates that the NiFe₂O₄/Ni(OH)₂ interface displays strong electronic interactions and triggers the formation of crystalline-amorphous coexisting catalytic active NiOOH. Meanwhile, the stable catalyst-collector interface favors the electron transfer and oxygen molecules transport. The resultant 2D NiFe₂O₄/Ni(OH)₂@CP electrode exhibits superior OER performance, including a low overpotential of 389 mV and a long operating time of 12 h at 1 A cm^-2. This work paves a novel method for fabricating efficient and low-cost electrocatalysts for electrochemical conversation devices.