A systematic study on the effects of Ni2+ and OH- ions on performance of direct ethanol fuel cell

At present, concerns about global warming, population growth, as well as the rapid decline of world oil supplies, caused the use of new energy sources is considered. As a result, in the last few decades numerous studies has been focused on the direct alcohol fuel cells (DAFCs). Electro-oxidation of ethanol on the nickel modified graphite electrode and effective parameters on its efficiency are investigated. Nickel modified graphite electrode is prepared by cycling at two cathodic and anodic potential ranges in nickel chloride and alkaline solutions, respectively. Nickel oxyhydroxide is formed by repetitive potential cycling in alkaline solution. The effect of nickel and hydroxide ions concentration on electro-oxidation of ethanol are studied. The results show that at a certain concentration of nickel deposited on graphite electrode, increasing the concentration of hydroxyl ion leads to an increase in the current density of ethanol oxidation as the result increase the kinetic of reaction of oxidation and the cell performance. On the other hand, the concentration of NiCl2 can affect the peak current density of ethanol electrooxidation. At a constant concentration of hydroxide, increasing the concentration of nickel ions up to a certain amount, can also increase the oxidation of ethanol. To find the optimum concentration of NiCl2 solution for preparing the modified electrode, in separate experiments, the graphite electrode modified by different concentrations of NiCl2. The concentration of 0.7 M NiCl2 is suitable enough for saturating the surface of the electrode by nickel ion and enhancement of ethanol oxidation