Abstract
Nickel hydroxide nanoflakes (Ni(OH)(2)-NF) were prepared by chemical deposition and in situ exfoliation of nickel hydroxide layers confined in the aqueous domain of the liquid crystalline hexagonal template of BrijA (R) 78 surfactant. Using excess of sodium borohydride as a reducing agent generates concurrent excessive dynamic hydrogen bubbles which exfoliated and fragmented the nickel hydroxide layers precipitated within the soft hexagonal template. The physicochemical characterizations of Ni(OH)(2)-NF by using surface area analyser, X-ray diffraction (XRD), XPS and transmission electron microscope (TEM) showed the formation of alpha-Ni(OH)(2) nanoflakes with thickness of 2-3 nm and have about 450 m(2) g(-1) surface area which is 20 times higher than that for bare nickel (bare-Ni) deposited without surfactant template. The electrocatalytic activity of the Ni(OH)(2)-NF catalyst for urea electrolysis was studied by cyclic voltammetry and chronoamperometry techniques. The Ni(OH)(2)-NF has shown a superior activity for the electrochemical oxidation of urea in alkaline solution and exhibits more than tenfold increase in activity in comparison with the bare-Ni deposit. The enhancement of urea electrooxidation activity was related to the superficial enhancement in the electroactive surface area of Ni(OH)(2)-NF. This new approach of deposition and in situ exfoliation by using liquid crystal template and hydrogen bubbles offers a new platform to nanostructuring wide range of catalysts with better catalytic performance.