M. G. Hosseini - Electrochemistry Research Laboratory, Department of Physical Chemistry, Chemistry Faculty, University of Tabriz, Tabriz, Iran
S. H. Mousavi - Electrochemistry Research Laboratory, Department of Physical Chemistry, Chemistry Faculty, University of Tabriz, Tabriz, Iran
v Daneshvari-Esfahlan - Electrochemistry Research Laboratory, Department of Physical Chemistry, Chemistry Faculty, University of Tabriz, Tabriz, Iran

Fuel cells are attractive sources of electrical power since they realize the direct conversion of chemical into electrical energy. Considerable interest has been directed to the use of fuel cells inelectric vehicle technology. One promising system is the direct methanol fuel cell (DMFC). Since it requires little additional equipment compared to the extensive gas process technology for methanol reforming, the fuel is best transported and converted into energy from the liquid state.In this research, we report the preparation and application of Ni/ZrO2-NTs/Zr electrode formed by anodizing of the zirconium substrate to produce ZrO2 nanotubes with subsequent cathodic deposition of nickel on these nanotubes. The electroactivity of the Ni/ZrO2-NTs/Zr electrode forthe methanol oxidation in alkaline solutions was studied by cyclic voltammetry. The results werecompared with those of the pure nickel. Fig. 1 shows cyclic voltammograms of (a) Ni/ZrO2-NTs/Zr in the presence of 0.1 M methanol (b) Ni in the absence of methanol (c) Ni in the presence of 0.1 M methanol in 0.5 M NaOH solution at a potential sweep rate of 100 mVs-1. It is observed from Fig. 1 that the presence ofmethanol in 0.5 M NaOH solution leads to the rapid increase in the anodic currents. The electrochemical oxidation of methanol at nickel electrodes can be represented by:Ni (OH) 2 → NiOOH + H+ + e- (1) NiOOH+ methanol → Ni (OH) 2 + oxidation products of methanol (2)The active NiOOH formed during the positive potential scan is consumed through Reaction 2. Subsequently, the formed Ni (OH) in Reaction 2 is again oxidized to NiOOH during the anodicpotential sweep. The current densities for methanol oxidation on Ni/ZiO2-NTs/Zr electrode are greater than that observed for flat nickel electrode. This implies that the Ni/ZrO2-NTs/Zr electrodes exhibit higher catalytic activity compared with flat nickel electrodes. This can be attributed to the larger surface area of the Ni/ZrO2-NTs/Zr electrodes.

Ni/ZrO2 NTs/Zr, Electrooxidation, Cyclic voltammetry, Methanol