Surface hydroxyl group-enriched nickel cobalt molybdate hydrate for improved oxygen evolution activity in an anion exchange membrane water electrolyzer

Abstract

The present report depicts a simple one-step reflux method to fabricate nickel cobalt molybdate hydrate (NCMH) nanostructured rods in gram-scale (>1.8 g). The structure and electrocatalytic oxygen evolution reaction (OER) activity of the NCMH have been explored both experimentally and theoretically. Further, experimental and theoretical analyses indicate that the presence of cobalt in NCMH promotes OH adsorption and enrichment of the NCMH surface with hydroxyl functionalities, which in turn improves the interfacial electrochemistry of NCMH to display better alkaline OER performance than either nickel molybdate hydrate or cobalt molybdate hydrate. In addition, the single cell anion exchange membrane (AEM) water electrolyzer containing an NCMH anode outperforms the commercial IrO2 anode with high current density of ∼1.0 A cm−2 at 1.82 Vcell and stable performance for 58 h with ∼74.57% cell efficiency. Therefore, nickel cobalt molybdenum oxide hydrate nanorods can serve as promising anode materials for AEM water electrolyzers.