Deep Reconstruction of Fe-NiMoO4·nH2O@NiOOH as Efficient Oxygen Evolution Electrocatalysts

In electrocatalytic hydrolysis, the oxygen evolution reaction (OER) reaction involves a four-electron transfer process. The complex transfer process reduces the rate of hydrolysis. Therefore, the electrocatalyst with good OER performance is desirable for not only fundamental research but also further application. Transition-metal electrocatalysts, as one of the alternatives to noble-metal catalysts, have abundant reserves and unique d orbital electrons. In particular, transition-metal molybdates undergo dynamic reconstruction at oxidation potentials, and the hydroxyl oxides formed after reconstruction are the main active species for oxygen-related reactions. In this work, we prepared self-supported Fe-doped NiMoO4·nH2O@NiOOH electrocatalysts by hydrothermal reaction and electrochemical oxidation. Porous NiOOH was generated on the surface of NiMoO4·nH2O by electrooxidation, and Fe doping was realized in this process. The porous structure of the surface is conducive to the penetration of the electrolyte, which can accelerate the ion transport rate. The doping of Fe was used to modulate the electronic structure and improve the electrocatalytic activity. The overpotential was only 227 mV at 10 mA/cm2 in the 1 M KOH electrolyte. In addition, the electrocatalyst exhibited high stability at a current density of 20 mA/cm2.