Electro-Oxidation of Ethanol and Propanol at Pt and Ti Modified Nanoparticle Substrates for Direct Alcohol Fuel Cells (DAFCs)

Modified Pt and Ti substrates were prepared by electrodeposition of nanocrystallite Pt and Ptx-Sny catalysts for electro-oxidation of ethanol, 1-propanol and 2-propanol. The chemical composition, the phase structure and the surface morphology of the Pt and Ptx-Sny electrodeposits were studied by X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscope (SEM). Their electro-catalytic activities were studied in 0.5 M H2SO4 by cyclic votlammetry and chronoamperometric techniques. It was found that, the nature of the substrate significantly affects the performance of the prepared catalyst towards electro-oxidation of different alcohols. Accordingly, the modified Pt substrates display enhanced catalytic activity and a higher stability towards alcohols electro-oxidation compared to the modified Ti substrates. Steady state Tafel plots experiments showed smoother and higher rate of alcohols oxidation on the modified Pt substrates than that on the modified Ti. High anodic Tafel slopes >200 for 1-propanol and 2- propanol electro-oxidation were obtained on Ti modified substrates indicating the complexity of the oxidation reaction on such electrodes.