Oxygen evolution catalyst containing CoNi nanoalloy and carbon nanotube maximized the electrochemical surface area and intrinsic activity

Abstract

To improve green-energy technology involving metal–air batteries, developing an efficient electrocatalyst for the oxygen evolution reaction (OER) and unveiling the factors that influence OER performance are crucial. Herein, we pyrolyzed the zeolitic imidazole framework to synthesize an N-doped carbon-based catalyst with a carbon nanotube (CNT) and the bimetallic CoNi nanoalloy. In addition, we optimized the size of CoNi particles and the formation of CNTs by controlling the reduction temperature (CoNi–CNT/NC-x; x is the reduction temperature). CoNi–CNT/NC-900 had the smallest CoNi nanoalloy particles, and CNTs were formed in CoNi–CNT/NC-600, -700, and −800 but not in −900. This infers that the ultrasmall CoNi nanoalloy particles and the formation of CNTs on their surface may come down to increasing the OER activity. Accordingly, the CoNi–CNT/NC-800 catalyst exhibited the highest OER performance (Ej10 = 1.53 V). This study proposes the rational design of an optimized catalyst with simple reduction condition control.