Abstract
Water electrolysis is a promising strategy to produce green hydrogen. However, this process is hampered by the high cost of precious electrode and the sluggish kinetics of oxygen evolution reaction (OER). Thus, it is desirable for developing an efficient and low-cost OER electrocatalyst. Herein, N and Fe co-doped CoO nanoparticles (CoxFeyO-N), rich of O vacancies and the interface of CoO/CoxN, were successfully prepared via the annealing of Fe doped cobalt-based coordination polymers in an NH3 atmosphere. The ratio of Co2+ and Fe3+ was systematically varied, and Co0.89Fe0.11O-N possesses the highest OER activity in 1.0 M KOH. Furthermore, through growth of the resultant Co0.89Fe0.11O-N onto nickel foam, the corresponding OER activity can be further enhanced with the overpotential of 360 mV at current density of 50 mA cm(-2). The superior OER activity of Co-0.8,Fe11O-N originates from the presence of oxygen vacancies and CoO/CoxN interface. During the reaction, CoO-N was partially oxidized into Co3O4, which accompanies CoO to co-catalyze OER. The study provides new insights for the preparation and understanding the active sites for Co-based catalysts for OER. (C) 2021 Elsevier B.V. All rights reserved.