Double etch strategy induced morphologic transformation engineering of Fe–Ni hydroxide for the efficient and stable oxygen evolution

Abstract

Developing high-efficiency and steady nickel-iron based catalysts are of great significance for oxygen evolution reaction (OER). However, the rarity of active sites exposed to electrolytes is difficult, limiting their OER properties. Herein, an innovative double-etch strategy has been developed to synthesize Fe–NiOH@NF nanosheet supported on nickel foam. Where NH4+ was applied to change the morphology of precursor (NiNH4PO4) from one-dimensional (1D) to two-dimensional (2D) to expose a larger solution contact area and the etch of OH− thinned the layered structure in the process of transforming Fe–NiNH4PO4 for Fe-β-Ni(OH)2. And the double etching strategy makes Fe–NiOH@NF-5 possess excellent electrocatalytic OER performance, when reaching the current densities of 100 and 1000 mA cm−2, the obtained catalytic materials only required a low overpotential of 260 and 320 mV, respectively. Meanwhile, the stability of the structure was also verified in strong corrosion environment (1 M KOH), and the catalytic activity presents unattenuated after stable operation at 100 mA cm−2 for 80 h. Density functional theory (DFT) confirmed that the optimized adsorption intermediates and conductivity were the keys to the better performance. The morphology control strategy of this work provided a significant reference for the improved OER properties of transition metal-based catalysts.