Deep Reconstruction\nof Fe-NiMoO₄·<i>n</i>H₂O@NiOOH\nas Efficient Oxygen Evolution Electrocatalysts

Abstract

In electrocatalytic hydrolysis, the oxygen evolution\nreaction (OER)\nreaction involves a four-electron transfer process. The complex transfer\nprocess reduces the rate of hydrolysis. Therefore, the electrocatalyst\nwith good OER performance is desirable for not only fundamental research\nbut also further application. Transition-metal electrocatalysts, as\none of the alternatives to noble-metal catalysts, have abundant reserves\nand unique d orbital electrons. In particular, transition-metal molybdates\nundergo dynamic reconstruction at oxidation potentials, and the hydroxyl\noxides formed after reconstruction are the main active species for\noxygen-related reactions. In this work, we prepared self-supported\nFe-doped NiMoO₄·<i>n</i>H₂O@NiOOH\nelectrocatalysts by hydrothermal reaction and electrochemical oxidation.\nPorous NiOOH was generated on the surface of NiMoO₄·<i>n</i>H₂O by electrooxidation, and Fe doping was realized\nin this process. The porous structure of the surface is conducive\nto the penetration of the electrolyte, which can accelerate the ion\ntransport rate. The doping of Fe was used to modulate the electronic\nstructure and improve the electrocatalytic activity. The overpotential\nwas only 227 mV at 10 mA/cm² in the 1 M KOH electrolyte.\nIn addition, the electrocatalyst exhibited high stability at a current\ndensity of 20 mA/cm².