Metal–Organic Framework-Derived Fe-Doped CoF2/NF Composite as Bifunctional Electrocatalyst for Oxygen Evolution and Hydrazine Oxidation

High-efficient, low-price electrocatalysts for electrochemical water splitting are critical for clean energy technology. In this work, a bifunctional electrode of Fe-doped CoF2 nanorod on nickel foam (Fe–CoF2/NF) is successfully prepared using a three-step synthesis process, involving room-temperature coprecipitation and ligand exchange reaction followed by low-temperature fluorination. As expected, the obtained Fe–CoF2/NF self-supported electrode shows favorable oxygen evolution reaction (OER) and hydrazine oxidation reaction (HzOR) performance that benefited from a hollow nanorod structure with a lot of nanoparticles caused by fluorination reaction etching, doping by Fe, and rapid reconstruction of metal fluoride, which can increase electrochemical surface area, expose more active sites, and accelerate reaction kinetics. The Fe–CoF2/NF electrode can drive a current density of 10 mA cm–2 at a low overpotential of 210 mV, with outstanding durability in 1.0 M KOH. More impressively, the electrode delivers an extra low potential of 0.67 V at 10 mA cm–2 for HzOR in 1.0 M KOH/0.5 M N2H4, significantly reducing the potential of OER. The HzOR also exhibits outstanding stability, and the current density retention ratio is approximately 87.5% after 60 h. Thus, this work provides a strategy to design transition-metal fluoride with high efficiency OER and HzOR.