Unique nanosheet–nanowire structured CoMnFe layered triple hydroxide arrays as self-supporting electrodes for a high-efficiency oxygen evolution reaction

Abstract

Developing highly active and low-cost electrocatalysts for the oxygen evolution reaction (OER) to meet industrial criteria is vitally essential. The control of morphology and microstructure on micrometer and nanometer scales has been widely applied as one of the most promising approaches for upgrading the catalytic abilities of electrocatalysts. Herein, novel CoMnFe layered triple hydroxide (LTH) arrays with a unique nanosheet–nanowire structure grown directly on 3D Ni foam (NF) have been first synthesized by controlling the incorporation of Fe. According to the morphology evolution with the key factors of hydrothermal treatment time and Fe addition, a possible formation mechanism of the nanosheet–nanowire microstructure has been proposed. Remarkably, this nanosheet–nanowire nanostructure of Co₄Mn₁Fe₃ LTH/NF can effectively lead to an intricate transportation network, uniform active site distribution at the nanoscale, electronic conductivity increase and open-channels for fast gas release, and thus significantly enhances the electrocatalytic activity of the material in the alkaline medium. The Co₄Mn₁Fe₃ LTH/NF can reach a current density of 100 mA cm⁻² at an ultralow overpotential of 226 mV with a small Tafel slope of 55 mV dec⁻¹ and exhibit strong durability for at least 100 h. Such superior OER activity is comparable to that of reported state-of-the-art OER catalysts. This work may greatly advance the research towards designing efficient electrocatalysts for the OER.