Layered transition metal oxyhydroxides as tri-functional electrocatalysts

Abstract

Layered transition metal-based materials have been intensively explored for their electrocatalytic capabilities in energy-related applications such as the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) lately. These reactions are kinetically sluggish, and require catalysts to promote their efficiency. Since their discovery and characterization decades ago, the catalytic properties of metal oxyhydroxides have not been profoundly studied. It was only in recent years when emphasis was placed on them again, mainly as possible OER catalysts. In this work, we wish to delve deeper into several layered first-row transition metal (cobalt, chromium, iron, manganese and nickel) oxyhydroxides, and investigate their inherent electrochemistry and electrocatalytic behaviors for HER and OER, as well as the oxygen reduction reaction (ORR). Characterisation of these materials was performed using scanning electron microscopy, X-ray powder diffraction, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy prior to electrochemical studies. Among the five layered oxyhydroxides examined, cobalt and nickel oxyhydroxides exhibited better electrocatalytic properties than the other three layered oxyhydroxides mainly in HER and OER.