Mesoporous cobalt hydroxide prepared using liquid crystal template for efficient oxygen evolution in alkaline media

Abstract

Active, stable and economical electro-catalysts are very necessary for hydrogen production through water splitting by electrolysis. This work reports the synthesis and characterization of highly porous cobalt hydroxide (meso-Co-OH) formed by a simple chemical precipitation within the interstitial space of liquid crystal template. The physicochemical properties of the meso-Co-OH were characterized by surface area analyzer, X-ray diffraction, XPS, scanning and transmission electron microscopes. The meso-Co-OH exhibits low crystallinity and high surface area of 457±5m2/g with a mesoporous structure and pore diameter of 4.0±1.0nm. As confirmed by the electrochemical characterizations, the meso-Co-OH is highly effective electro-catalyst for oxygen evolution reaction (OER) at low applied potential and shows superior activity and stability than iridium oxide during long term water electrolysis in alkaline media. The meso-Co-OH shows oxygen evolution current and onset potential comparable to the IrO2 catalyst and the current is enhanced by 10 times than the values of bulk cobalt hydroxide electrode. For meso-Co-OH catalyst the oxygen evolution overpotential of 1.55V (vs. RHE) at current density of 25mA cm2 has been achieved in 1.0M KOH. The enhanced OER activity was attributed to the substantial increase in the active catalyst surface area due to the formation of mesoporous network within the cobalt hydroxide framework.