Electrocatalysis of Ni-promoted Cd coated graphite toward methanol oxidation in alkaline medium

Abstract

The nickel–cadmium (Ni-promoted Cd) catalyst for using direct methanol fuel cell (DMFC) applications is electrochemically deposited on a graphite substrate. The activity of methanol oxidation is assessed by recording cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) techniques. The surface morphologies and chemical compositions of catalysts are determined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray florescence spectroscopy (XRF). Mean roughness of catalysts is measured by atomic force microscopy (AFM). Kinetic parameters of oxidation such as the anodic electron transfer coefficient (˛a), cathodic electron transfer coefficient (˛c) and charge transfer rate constant (ks) are calculated. The effect of methanol concentration and temperature on methanol oxidation is also investigated. The electrochemical measurements show that the addition of Cd to single coating enhances the electrocatalytic properties for methanol oxidation and Ni-promoted Cd/C has the best catalytic activity and stability.