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

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 ± 5 m2/g with a mesoporous structure and pore diameter of 4.0 ± 1.0 nm. 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 1.55 V (vs. RHE) at current density of 25 mA cm2 has been achieved in 1.0 M 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.

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