1D self-supporting NiFe2O4/NiMoO4 heterostructure as bifunctional electrocatalyst via interface engineering for highly efficient seawater splitting

Direct seawater electrolysis is a promising way for hydrogen energy production. However, developing efficient and cost-effective electrocatalysts remains a significant challenge for seawater electrolysis with industrial-level current density due to high concentration of salts and compete reaction of chlorine evolution. Herein, a 1D NiFe₂O₄/NiMoO₄ heterostructure as a bifunctional electrocatalyst for overall seawater splitting is constructed by combining NiMoO₄ nanowires with NiFe₂O₄ nanoparticles on carbon felt (CF) by a simple hydrothermal, impregnation and calcination method. The electrocatalyst exhibits low overpotential of 237 and 292 mV for oxygen evolution reaction and hydrogen evolution reaction at 400 mA/cm² in the alkaline seawater (1 mol/L KOH + 0.5 mol/L NaCl) due to the plentiful interfaces of NiFe₂O₄/NiMoO₄ which exposes more active sites and expands the active surface area, thereby enhancing its intrinsic activity and promoting the reaction kinetics. Notably, it displays low voltages of 1.95 V to drive current density of 400 mA/cm² in alkaline seawater with its excellent stability of 200 h at above 100 mA/cm², exhibiting outstanding performance and good corrosion resistance. This work provides an effective strategy for constructing efficient and cost-effective electrocatalysts for industrial seawater electrolysis, underscoring its potential for sustainable energy applications.