Elucidation of nickel-iron chloride/oxychloride as a precatalyst for oxygen evolution reaction

This study unravels nickel-iron chloride/oxychloride as a unique precatalyst for oxygen evolution reaction. Chloride/oxychloride layers are electrodeposited on a permalloy surface upon sodium chloride etching to prepare the precatalyst. After chloride etching for 20 cycles (NiFe-NaCl-20) in NaCl, the oxygen evolution reaction (OER) activity of the pristine permalloy (B-NiFe) in 1.0 M KOH electrolyte is highly enhanced than those of the alloys eroded for 10 (NiFe-NaCl-10) and 30 cycles (NiFe-NaCl-30). In addition, the heterogeneous chloride/oxychloride electrode surfaces are transformed into active hydroxide/oxyhydroxide in KOH. Consequently, the as-prepared NiFe-NaCl-20 electrode required a low overpotential of 246 mV to achieve a current density of 10 mA cm-2 compared to the other investigated electrodes. The enhanced performance may be attributed to the formation of numerous high-valent chloride/oxychloride species on the NiFe-NaCl-20 electrode surface. These results indicate that nickel-iron chloride/oxychloride is a competent precursor for developing an active OER electrode. (c) 2023 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.