Investigation On The Effect Of Acetaldehyde And Acetic Acid On The Electrooxidation Behavior Of Ethanol By Cyclic Voltammetry

As an alternative to methanol,ethanol is safer,non-toxic,more convenient ,and has greater energy density(8.01kWh/kg),in addition,ethanol can be easily produced in great quantity through fermentation of sugar-containing raw materials. But the commerce of DEFC has so many difficulties.Therefore,the mechanism of ethanol oxidation and anode electrocatalysts has been extensively studied and is still the subjects of interest. In this thesis,the preparation of anode catalysts,the influence of acetaldehyde and acetic acid and the mechanism of ethanol oxidation are investigated systematically.Ethanol oxidation using Pt particles deposited over Pt electrode as electrocatalyst showing high electrocatalytic activities.The high electrocatalytic activities of the Pd particles deposited over graphite electrode as electrocatalyst towards the oxidation of ethanol in alkaline medium.Pt electrode with electrodeposited Platinum particles which are uniformly dispersed by cyclic voltammetry in chloroplatinic acid solution. The results of cyclic voltammetric and AC impedance testing shows that the process of ethanol oxidation is irreversible and diffusion controlled.Electrochemical properties of this electrode composites indicate that a higher electrocatalytic activity has been shown in oxidation of ethanol.Influence of acetaldehyde and acetic acid on the ethanol oxidation reaction is respectively studied by cyclic voltammetry. The results demonstrate that the decreased oxidation peak current of ethanol is not simply originated from acetaldehyde, and the polymer of acetaldehyde adsorbed on surfaces of Pt electrode hindered ethanol oxidation reaction. Acetic acid also inhibited ethanol oxidation reaction, probably due to the formation of ethyl acetate during the ethanol electrooxidation process.Electrochemical methods are used to investigate the electrooxidation behavior of ethanol in different media. It is found that the higher acidity of solution and lower concentration of Na2SO4 is favorable to ethanol oxidation within concentration range of H2SO4 is 0.05-1.0mol/L and Na2SO4 is 0.1-0.5mol/L. In acid media containing Na2SO4, the addition of H2SO4 is not beneficial to the ethanol oxidation. But when in alkaline media whether or not containing Na2SO4, higher concentration of NaOH is not helpful to the oxidation of ethanol.Graphite electrode with electrodeposited Pd particles by potentiostatic method. The results of cyclic voltammetry and AC impedance testing indicate that a higher electrocatalytic activity has been shown in oxidation of ethanol.