Determination of Reaction Mechanisms Occurring at Fuel Cell Electrocatalysts Using Electrochemical Methods, Spectroelectrochemical Measurements and Analytical Techniques

Abstract

There is now a great interest in developing different kinds of fuel cells for several applications (stationary electric power plants, transportation, portable electronic devices). For many applications, hydrogen is the most convenient fuel, but it is not a primary fuel, so that it has to be produced from different sources: water, fossil fuels (natural gas, hydrocarbons, etc.), biomass resources, etc. When produced from fossil fuel and biomass resources, hydrogen gas contains a non negligible amount of CO, which acts as a poisoning species for platinum electrocatalysts. Other fuels, particularly alcohols, which are liquid under ambient temperature and pressure, are more convenient due to the easiness of their handling and distribution and high theoretical energy density (6 to 8 kWh kg−1, for methanol and ethanol, respectively). Direct Methanol Fuel Cells (DMFCs) and Direct Ethanol Fuel Cells (DEFCs) are based on the Proton Exchange Membrane Fuel Cell (PEMFC) system, in which hydrogen is replaced by the alcohol. Moreover, due to the presence of carbon monoxide, the issues for PEMFCs working with reformate gas are close to those met in Direct Alcohol Fuel Cells (DAFCs), where the dissociative adsorption of alcohol leads to the formation of adsorbed CO species.