Concurrent Deposition and Exfoliation of Nickel Hydroxide Nanoflakes Using Liquid Crystal Template and Their Activity for Urea Electrooxidation in Alkaline Medium

• Published in: Electrocatalysis 2017, Vol.8 (1), p.16-26
• Main Authors: Ghanem, Mohamed A., Al-Mayouf, Abdullah M., Singh, Jai P., Arunachalam, Prabhakarn
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts; Chemistry; Chemistry and Materials Science; Electrochemistry; Energy Systems; Original Research; Physical Chemistry; Surface area; Surfactants; Transmission electron microscopy; Voltammetry; X-ray diffraction
• ISSN: 1868-2529; 1868-5994
• DOI: 10.1007/s12678-016-0336-8

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 Brij®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 α-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. Graphical Abstract Nickel hydroxide nanoflakes (Ni(OH) 2 -NF) catalyst for the electrochemical oxidation of urea in alkaline solution.