Electrochemical synthesis of Li-doped NiFeCo oxides for efficient catalysis of the oxygen evolution reaction in an alkaline environment

Abstract

Oxygen evolution reaction (OER) is an essential reaction for overall electrochemical water splitting. In this present study, we adopt a facile electrochemical deposition method to synthesize the Li-doped NiFeCo oxides for OER in an alkaline medium. The scanning electron microscopy, X-ray diffraction, Brunauer-Emmet-Teller method and X-ray photo-electron spectroscopy provides the information of morphology, structure, specific surface area and electronic state of the electrocatalysts respectively. Investigates the electrochemical properties by the thin-film technique on a rotating disk electrode and in a single-cell laboratory water electrolyzer connects with electrochemical impedance spectroscopy. Among the catalysts under investigation, Ni0·9Fe0·1Co1·975Li0·025O4 exhibits the highest activity towards oxygen evolution reaction, and explains the activity by the oxygen binding energy; such knowledge can be helped to develop better catalyst. We achieve onset over potential 220 mV and receive 10 mA cm−2 current density at over potential 301 mV with Tafel slope 62 mV dec−1 in 1 M KOH solution. The results are similar to recently published catalysts in the literature. In water electrolyzer, the Ni0·9Fe0·1Co1·975Li0·025O4 modified nickel foam anode exhibits a current density of 143 mA cm−2 at a cell voltage of 1.85 V in 10 wt% KOH and a temperature of 50 °C.