Abstract
In this research, the electro-catalytic activity of nickel-copper (Ni-Cu) alloy towards oxidation of ethanol and its possible redox process were investigated in alkaline solution. For this purpose, cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy techniques were employed. According to the cyclic voltammetry studies, Ni- Cu alloy compared to pure nickel can demonstrate a significantly higher response for ethanol oxidation. So, the enhancement of the anodic peak current corresponding to the oxidation of nickel hydroxide was accompanied with attenuated cathodic current in the presence of ethanol. The anodic peak currents have a linearly dependence on the square root of scan rate which is the characteristic of diffusion-controlled processes. Based on the chronoamperometry measurements, the reaction exhibited a Cottrellian behavior and the diffusion coefficient of ethanol was found to be 1.26 - 10-5 cm2 s-1. The impedance spectroscopy declared electro-catalytic behavior of Ni-Cu electrode for oxidation of ethanol and showed that the charge transfer resistance decreases by increasing the ethanol concentration.
Highlights
Direct ethanol fuel cells (DEFCs) have attracted much interest for different applications.[1,2] The reason is that they can provide convenient operation, storage and distribution
The aim of present work is to study the electrochemical oxidation of ethanol on Ni-Cu alloy (70/30) electrode in alkaline solution and compare its catalytic activity with pure Ni electrode via electrochemical techniques of cyclic voltammetry, chronoamperometry and impedance spectroscopy
Surface coverage of the redox species, G*, can be calculated according to the slope of the lines shown in Figure 3b:33 trode is high for ethanol oxidation, but it is at higher anodic over-potentials
Summary
Direct ethanol fuel cells (DEFCs) have attracted much interest for different applications.[1,2] The reason is that they can provide convenient operation, storage and distribution. Utilizing alkaline solution has many advantages in fuel cells It can enhance fuel cell efficiency, reduce corrosion, enable the application of many electrode materials, promote efficiency of the processes occured at both anode and cathode, eliminate sensitivity to the surface structure and decrease poisoning effects.[5,6,7,8]. Some studies have reported a significant increase in fuel utilization and power density through optimizing different factors related to fuel cells.[9,10] For the electrode, different materials have been employed to catalyze the electrochemical oxidation of ethanol.[11,12] One of the well-established electrode materials is nickel which poses proper surface oxidation properties. The aim of present work is to study the electrochemical oxidation of ethanol on Ni-Cu alloy (70/30) electrode in alkaline solution and compare its catalytic activity with pure Ni electrode via electrochemical techniques of cyclic voltammetry, chronoamperometry and impedance spectroscopy
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