Enhanced electrocatalytic efficiency of C/MWNTs for methanol oxidation using Ni deposited on MWNTs

Abstract

The power density of direct methanol fuel cells (DMFCs) can be changed by using different anode materials. Especially porous materials are preferred for the anode. In the present study, multiwall carbon nanotubes were first injected into graphite. Then, by depositing nickel, a catalyst was prepared for use as the anode material of the DMFC. This catalyst was named Ni@MWNTs. The oxidation of methanol and some kinetic parameters were investigated in KOH solution. Cyclic voltammetry was used for the electrochemical measurements. Kinetic parameters of the methanol oxidation were determined at different temperatures, scan rates, and concentrations of methanol. The surface morphologies and nickel deposition amounts of the Ni@MWNTs and Ni-C (nickel deposited graphite) electrodes were characterized with scanning electron microscope (SEM), atomic force microscope (AFM), and energy-dispersive X-ray (EDX) spectroscope. It was found that the Ni@MWNTs electrode was more active than the Ni-C electrode. The activation energy of the Ni@MWNTs electrode was calculated as 19.52 kJ mol$^{-1}$ for the methanol oxidation process.