Effect Of Anode Pollutant Hydrogen Sulfide On Proton Exchange Membrane Fuel Cell Performance

Proton exchange membrane fuel cell (PEMFC) is considered as most ideal power source and hopefully clean technology, due to its advantages of high efficiency, high energy density, low emission and easy transportation and storage of the fuel. Hydrogen fuel cells use hydrogen as fuel gas. One of the important factors which restrict the wide application of a PEMFC is the sources of hydrogen. At present, preparation for hydrogen by refored gases is the most practical options. However, because of restrictions on hydrogen technology, unpurified raw materials and intermediate products, it will lead to impurities, such as carbon oxides, nitrogen oxides and sulfide etc. So it is great significance to the development of PEMFC to solve the problem of the hydrogen sulfide poisoning problem.We studied the effect of hydrogen sulfide on the PEMFC performance by the polarization, cyclic voltammetry, potential step, current block, electrochemical impedance and other electrochemical methods. By studying the relationship between concentrations of hydrogen sulfide and PEMFC performance, we found that the adsorption of hydrogen sulfide on platinum catalyst can be cumulative bad effects. Even if the concentration of hydrogen sulfide less than 2 part per million, the long period effects will result in a decline of cell performance.That is not the ideal way only by control the concentration of hydrogen sulfide in fuel to maintain the properties of cell. We need to taken measures to restore the battery performance. Some methods, that using pure hydrogen, polarization, cyclic voltammetry and potential step method, had been adopted to recover cell performance. The performance cannot be restored with pure hydrogen and polarization curves way.It can be completely recovered by cyclic voltammetry and potential step method.We took ways such as electrochemical impedance spectroscopy and the current blocking researching on poisoning and recovery mechanisms. The results show that the adsorption of hydrogen sulphide caused the production of Pt-S layer which lead difficult adsorption of hydrogen and the increasing of electrochemical reaction resistance. The same characteristic of cyclic voltammetry and potential step method is the application of high potential to oxidize Pt-S adsorbate substance on electrode surface. Then, Pt surface would be fully restored to the oxidation of hydrogen.