Fabrication and Characterization of Controlled-Morphology Self-Supported Fe/Co Layered Double Hydroxides as Catalysts for the Oxygen Evolution Reaction

Electrochemical water splitting is a promising method of hydrogen production that involves two half reactions, namely the fast hydrogen evolution reaction and the slow oxygen evolution reaction (OER). The latter reaction can be accelerated by electrocatalysts, which reduce its overpotential to improve energy conversion efficiency. Herein, Fe-doped Co layered double hydroxides on 3D Ni foam (CoxFey-LDH/NF) with different Co/Fe molar ratios were hydrothermally synthesized in a single step and evaluated as OER catalysts. Structural and electrochemical characterizations provided insights into the origin of the synergistic effect of Fe and Co on OER performance enhancement and indicated that catalyst composition, crystal/electronic structure, and surface morphology are strongly related to Fe content. The best-performing catalyst, Co3Fe1-LDH/NF, exhibited a nanoneedle morphology, an overpotential of 201 mV at a current density of 10 mA cm−2, a small Tafel slope of 47.9 mV dec−1, and satisfactory long-term electrochemical stability in 1.0 M KOH. Thus, this work emphasizes the significance of effective structure design via precise control of catalyst morphology for the development of non-precious metal electrocatalysts.