Electrochemical Properties And Characterization Of Organic Polyols As Alternative Fuel For Direct Methanol Fuel Cell

Direct methanol fuel cells(DMFCs) use methanol as fuel, in the transport, storage, use and so on has high security, coupled with a high specific energy, so methanol as fuel have attracted increasingly attention. However, DMFC existence methanol permeability (Methanol Crossover), electro-catalyst poisoning and other issues, so look for new alternative methanol fuel into one of a hot attention. Among them, alternative fuels for the straight-chain primary alcohol molecules, in particular C1-C5 primary alcohols of more reports. But few reports of increase carbon branched-chain and relevant the number of hydroxyl (-OH) such as organic molecules polyols. As the polyols'hydroxyl (-OH) are numerous, larger molecules, so it can greatly reduce the permeability of molecules which through the proton exchange membrane, and improve fuels efficiency. Therefore, study on the electrochemical performance of polyols, for alternative fuels provide an important reference value. In this paper, using cyclic voltammtry method (CV) study on neopentyl glycol (NPG), trimethylol ethane (PG) and pentaerythritol (PE) of the three polyols for the influence of electrochemical behavior at different conditions on bare platinum electrode. Compare the electrochemical behavior of the three polyols on the bare platinum electrode, the dispersed platinum electrode (Pt/Pt) and polyaniline-modified dispersed platinum electrode (Pt/PAni/Pt) respectively. Using electrochemical method compare the permeability of neopentyl glycol (NPG), trimethylol ethane (PG) and methanol in the Nafion membrane. The main contents are as follows:CV method study on the electrochemical behavior of organic molecules polyol neopentyl glycol (NPG), trimethylol ethane (PG) and pentaerythritol (PE) on the bare platinum electrode, results showed that the greater sweep speed, higher temperature, the more it will benefit the electrooxidation of three polyols; in a certain range of concentration, the greater the concentration of alcohol solution, but smaller H2SO4 solution, the more conducive to the electrooxidation of polyols. At the potential between -0.2-1.2V, the oxidation peak current of three kinds of polyols are far less than of methanol.Polyaniline synthesized by CV method used for the catalyst Pt load. Because of this special structure of polyaniline improved the dispersion of platinum particles, and increase the utilization of platinum particles in the catalyst system. Scanning electron microscopy (SEM) results showed that, the mean particle size of the platinum particles on Pt/Pt electrode is 240nm or so, on Pt/ PAni/Pt electrode is about 150nm. Impedance test results show that, the electrochemical reaction resistance of Pt/PAni/Pt electrode and Pt/Pt electrode decreases compare to the bare platinum electrode, meanwhile the catalytic activity increased. By comparing the Neopentyl Glycol(NPG), trimethylol ethane(PG) and pentaerythritol(PE), it can be seen that on Pt/PAni/Pt electrode the peak current is far more than on Pt/Pt electrode and bare platinum electrode.Cyclic voltammetry(CV) and chronoamperometry(CA) were used, calculate the permeability of methanol, neopentyl glycol and trimethylol ethane in the Nafion membrane. The results showed that the permeability of methanol is far greater than the Neopentyl Glycol(NPG) and trimethylol ethane(PG). Chronoamperometry(CA) results show that as time grown the three alcohols cross over Nafion membrane permeability also increases.