New route for synthesis of electrocatalytic Ni(OH)2 modified electrodes—electrooxidation of borohydride as probe reaction

Immobilization of redox species like Ni(OH)2 onto the electrode surface is important in the application areas such as super capacitor, electrochromic displays and electrocatalysis. Nickel hexacyanoferrate (NiHCF) modified glassy carbon could be further derivatized with Ni(OH)2 by electrochemical cycling in alkali. The electrodeposition of Ni(OH)2 was usually carried out onto the electrode surface from nickel salt at high interfacial pH. This paper reports the preparation of Ni(OH)2 from insoluble nickel tetracyanonickelate supported on carbon (NTN/C). This insoluble precursor complex was decomposed by two methods. (1) By potential cycling of modified electrode with the above complex in alkali. (2) By thermal decomposition of the precursor complex (NTN/C) to form metallic nickel followed by cycling in alkali. Ni(OH)2 modified electrodes formed using both methods were characterized by cyclic voltammetry and also by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. Further, electrocatalytic properties of Ni(OH)2/C modified electrodes formed by the above two methods were studied and compared using borohydride oxidation as probe reaction.