Cation-vacancy-rich NiFe₂O₄ nanoparticles embedded in Ni₃Se₂ nanosheets as an advanced catalyst for oxygen evolution reaction

Developing efficient and economically viable approaches to produce non-noble metal electrocatalysts with high performance is crucial for anion exchange membrane water electrolyzers. Here, we present a novel and mild two-step method to producing highly active and stability NiFe₂O₄/Ni₃Se₂ electrocatalyst by utilizing the dissolution/redeposition effect. Notably, the NiFe₂O₄ nanoparticles (∼10 nm) wrapped by Ni₃Se₂ nanosheets creating plentiful heterostructures and strong coupling forces to realize high-efficient alkaline water electrocatalysis. Therefore, the NiFe₂O₄/Ni₃Se₂ electrocatalyst delivers current densities of 1000 mA cm⁻² under overpotentials of 379 mV for alkaline oxygen evolution and operates over 1200 h across a range of current densities from 50 to 1000 mA cm⁻². An anion exchange membrane water electrolyzers with NiFe₂O₄/Ni₃Se₂ electrocatalyst exhibits performance (1.85 V @ 0.5 A cm⁻², 2.08 @ 1.0 A cm⁻²) superior to that of the benchmark device at room temperature, and robust stability under industrial conditions. Experimental results and theoretical investigations demonstrate that the special encapsulation structure effectively mitigated catalyst migration and modulated the adsorption of O-containing intermediates. This work provides a rational synthesis strategy and provides useful guidelines to facilely fabricate oxygen evolution reaction electrocatalyst with high performance for an industrial water electrolyzer.