Synthesis of self-supported NiCoFe(OH)x via fenton-like effect corrosion for highly efficient water oxidation

Efficient and inexpensive oxygen evolution reaction (OER) catalysts are essential for the electrochemical splitting of water into hydrogen fuel. Herein, we have successfully synthesized NiCoFe(OH)_x nanosheets on Ni-Fe foam (NFF) by exploiting the Fenton-like effect of Co²⁺ and S₂O₈²⁻ to corrode the NFF foam. The as-prepared NiCoFe(OH)_x/NFF exhibits the porous structure with the interconnected nanosheets that are firmly bonded to the conductive substrate of NFF, thereby enhancing ions and charge transfer kinetics. The unique structure and composition of NiCoFe(OH)_x/NFF result in the low overpotentials of 200 and 262 mV at current densities of 10 and 100 mA cm⁻², respectively, as well as a low Tafel slope of 53.25 mV dec⁻¹. In addition, NiCoFe(OH)_x/NFF displays low overpotentials of 267 and 294 mV at a high current density of 100 mA cm⁻² in simulated and real seawater, respectively. Furthermore, the assembled NiCoFe(OH)_x//Pt/C water electrolysis cell has achieved a current density of 10 mA cm⁻² at a low voltage of 1.49 V, and displayed the good stability with slight attenuation for 110 h. The high OER performance of NiCoFe(OH)_x is attributed to the co-catalytic effect of the three metal ions and the interconnected porous nanosheet structure.