Short communication Methanol electrooxidation on a nickel electrode modified by nickel–dimethylglyoxime complex formed by electrochemical synthesis Ahmad Nozad Golikand a, * , Mehdi Asgari a , Mohammad Ghannadi Maragheh a , Saeed Shahrokhian b a Jaber Ibn Hayan Research Laboratory, Atomic Energy Organization of Iran (AEOI), Karegare Shomali St., Tehran 11365-8486, Iran b Faculty of Chemistry, Sharif University of Technology, Tehran 11365-9516, Iran Received 19 June 2005; received in revised form 27 November 2005; accepted 29 November 2005 Abstract Nickel–dimethylglyoxime complex (NiDMG) modified nickel electrode (Ni/NiDMG) showed a catalytic activity towards methanol oxidation in NaOH solution. The modified electrode prepared by the dimethylglyoxime anodic deposition on Ni electrode in the solution containing 0.20 mol L 1 NH 4 Cl + NH 4 OH (pH 9.50) and 1.0 · 10 4 mol L 1 dimethylglyoxime. The modified electrode conditioned by potential recycling in a potential range of 100–700 mV (vs. SCE) by cyclic voltammetry in alkaline medium (0.10 M NaOH). The results show that the NiODMG film on the electrode behaves as an efficient catalyst for the electrooxidation of methanol in alkaline medium via Ni(III) species formed on the electrode with the cross exchange reaction occurring throughout the film at a low concentration of meth- anol. A plausible mechanism was proposed for catalytic oxidation of methanol at NiODMG-modified Ni electrode. Moreover, the effects of various parameters such as anodic deposition time, anodic deposition potential (both in modification step), potential scan rates, meth- anol concentration and media temperature on the electrooxidation of methanol were investigated. Ó 2005 Elsevier B.V. All rights reserved. Keywords: Electrocatalytic oxidation; Methanol; Nickel; Nickel dimethylglyoxime; Modified electrode; Electrochemical synthesis 1. Introduction The electrocatalytic oxidation of alcohols has received significant amount of interest because of its applications in direct methanol fuel cells [1–4]. The literature on electro- chemical oxidation of alcohols can be roughly grouped into two sets: fuel cells and homogenous catalysis. Work on fuel cells primarily focuses on surface science/electrochemistry approach, single molecule catalysts are generally not considered. In contrast, the inorganic community’s investi- gation of the electrooxidation of alcohols primarily con- sisted of homogenous systems. The alcohol substrates are typically either secondary alcohol such that the reaction stops after 2 e  oxidation to the ketone or primary alcohols so that competition between 2 e  oxidation to the aldehyde and 4 e  oxidation to carboxylic acid is possible. Metha- nol, which can also undergo 6 e  oxidation to CO 2 , rarely appears in the homogeneous studies [3,4]. Recently, nickel complexes modified electrodes most widely have been used for electrocatalytic oxidation of alcohols especially methanol [5–11]. Macrocyclic com- plexes of nickel are interesting as modifying agents, because in alkaline media nickel redox centers show high catalytic activity towards oxidation of small organic com- pounds such as methanol [10,12]. Cataldi et al. [13,14] showed that the conductive microstructures formed in alkaline solutions provide a large dispersion of nickel- based catalytic sites which exhibit high electrocatalytic activity towards the oxidation of carbohydrates in alka- line medium and this effect for electrooxidation of meth- anol in alkaline solution is reported by Shyh-Jiun Liu [15]. 0022-0728/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jelechem.2005.11.033 * Corresponding author. Tel.: +98 21 8008965; fax: +98 21 8638749. E-mail address: anozad@aeoi.org.ir (A.N. Golikand). www.elsevier.com/locate/jelechem Journal of Electroanalytical Chemistry 588 (2006) 155–160 Journal of Electroanalytical Chemistry