How Reactive are Metal Surfaces in Solution? A Comparison of the Electrochemical Adsorption of Organic Molecules on Pt At Low Potentials

Abstract

IntroductionTransition metal surfaces are widely employed as catalysts ofchemical reactions, both at the metal/gas [1] and at the metal/solution [2] interfaces. Well-known examples are ceramic-supportedcatalystsusedingasexhaustsofvehiclestooxidizepartially burnt fuels [3] and metal-based catalysts used in fuelcell devices to promote electrochemical oxidation of organicmolecules for direct conversion of chemical energy into elec-trical energy with high efficiency [4].In this context, the electrochemical oxidation of alcoholshasbeenextensivelystudiedinthelastdecades[5]duetotheirpotentialfor practical applicationsinfuelcells.Directalcoholfuelcell(DAFC),especiallydirectethanolfuelcell(DEFC),isbecominga veryattractivealternative energysourcefor fossilfuel combustion engines due to several advantages, includingits high theoretical efficiency, high energy density of alcohols(comparable to gasoline) [6], and the possibility of energyproduction from renewable sources [7]. However, for theDEFC to become commercially attractive, a few issues mustbeovercome.Oneofthedifficultiesisthatthecurrentstate-of-the-art anodes are not capable of fully oxidizing ethanol toCO