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

Abstract

High-efficient, low-price electrocatalysts for electrochemical water splitting are critical for clean energy technology. In this work, a bifunctional electrode of Fe-doped CoF 2 nanorod on nickel foam (Fe−CoF 2 /NF) is successfully prepared using a threestep synthesis process, involving room-temperature coprecipitation and ligand exchange reaction followed by low-temperature fluorination. As expected, the obtained Fe−CoF 2 /NF selfsupported 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−CoF 2 /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 N 2 H 4 , 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.

Taking Advantage of Potential Coincidence Region: Insights into Gas Production Behavior in Advanced Self-Activated Hydrazine-Assisted Alkaline Seawater Electrolysis

“…As shown in Figure d, FeCoP/NF exhibits higher electrocatalytic HzOR activity with higher reactive current densities at lower overpotentials, reaching a current density of 10 mA cm –2 at −127 mV, which is much lower than 22 mV for FeP/NF, −98 mV for CoP/NF, and many other recently reported highly efficient electrocatalysts (Figure g and Table S3). − HzOR under alkaline conditions is a four-electron transfer process N 2 H 4 + OH − → N 2 normalH 3 * + H 2 normalO + e − N 2 normalH 3 * + OH − → N 2 normalH 2 * + H 2 normalO + e − N 2 normalH 2 * + OH − → N 2 H * + H 2 normalO + e − N 2 H * + OH − → N 2 …”

Trimetallic Fe3O4@Au/MOF nanopolyhedrons with peroxidase-like catalytic activity for the electrochemical detection of tert-butyl hydroquinone as a pollutant in edible oil

“…It is known that hollow nanostructures with a large number of nanoparticles can be generated through the combination of metal clusters and organic ligands, which can increase the electrochemical surface area, expose more active sites, and accelerate the reaction kinetics, thus improving the catalytic ability of the materials. 22…”