Self-oxidized amorphous FeOx@NiOy electrocatalyst with double-shell hollow nanoarchitecture for boosting oxygen evolution reaction

Abstract

FeNi-based electrocatalysts are promising for oxygen evolution reaction (OER), but it is still challengeable to obtain unique nanoarchitecture with rich active sites and high OER activity. Herein, a novel self-oxidation strategy is proposed to convert FeNi hydrogels with core-shell structures into amorphous FeNi–O aerogels with double-shell (FeOx@NiOy) hollow nanoarchitecture by the Kirkendall effect. Attributed to the unique double-shell hollow nanoarchitecture, the FeNi–O aerogels own large specific surface area and porosity, which provides many more active sites for OER and facilitates ion diffusion and O2 release. Furthermore, the strong electron interactions occurring at the non-homogeneous interface of the double-shelled structure, can effectively accelerate the electron transfer thus boosting OER. In addition, the amorphous FeOx@NiOy double shell structure is benefit to maintain structural stability and prevent its corrosion by electrolyte. As a result, the FeNi–O aerogels deliver excellent OER activity with a low overpotential of only 280 mV at a high current density of 50 mA cm−2, a low Tafel slope of 32.5 mV dec−1, and good long-term catalytic stability. The work provides a facile, and low-cost strategy to develop hollow non-noble metal based electrocatalysts with boosted OER activity.