Improved trifunctional electrocatalytic performance of integrated Co3O4 spinel oxide morphologies with abundant oxygen vacancies for oxygen reduction and water-splitting reactions

Abstract

A simple and surfactant-free hydrothermal method was used to produce different forms of integrated nanostructures of Co3O4 spinel oxides, which exhibited excellent trifunctional electrocatalytic activity toward oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The surface morphology and structural features of Co3O4 spinel oxide catalysts were investigated, and 40–70-nm nanocube particles were found decorated over petal-, slab-, and flower-like spinel oxide structures with the dominant (111) crystalline plane. According to physicochemical studies, the Co3O4 spinel oxide catalyst with the slab morphology has a high Co3+/Co2+ ratio and an abundance of oxygen vacancies, resulting in improved trifunctional performance with an early ORR onset potential (0.91 V), low overpotential for OER (460 mV) and HER (363 mV), and extended durability. This study provides insights into the design and structural features of Co3O4 spinel oxides through a simple and template-free synthesis approach to compete as an efficient trifunctional electrocatalyst for water splitting and metal–air battery applications.