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

Abstract

Modified Pt and Ti substrates were prepared by electrodeposition of nanocrystallite Pt and Pt x -Sn y 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 Pt x -Sn y 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 H 2 SO 4 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.

The Effect of SnO₂ and Rh on Pt Nanowire Catalysts for Ethanol Oxidation

“…Generally, the Tafel slope provides insights into whether the rds involves the transfer of the first or second electron and whether a chemical reaction is involved [51]. The Tafel slope values were close to the theoretical value of 120 mV dec -1 obtained on carbon-supported Pt catalysts, consistent with a Temkin-type adsorption mechanism for both OHads and ethoxy adsorption at low potentials [52,53].…”

Realising the activity benefits of Pt preferential (111) surfaces for ethanol oxidation in a nanowire electrocatalyst

“…Tafel slopes around 120 mV dec -1 have been obtained on single-crystal carbon-supported Pt catalysts. Generally, the Tafel slope allows the observation of whether the rds is the transfer of the first or second electron and if a chemical reaction is involved [46]. Thus, for the synthesised Pt/C NWs catalyst, the obtained slope value (close to 120.0 mV dec -1 ) is in agreement with a mechanism that involves Temkin-type adsorption for both OH ads and ethoxy at low potentials [47].…”

Determination of Diffusion Coefficient of Isopropanol in Alkaline Medium using Electrochemical Methods on Pd Electrode~!2009-12-09~!2010-02-20~!2010-06-09~!

“…Some work has been done to investigate the electrooxidation of isopropanol on Pt-based catalysts in alkaline medium [9,10]. However, Pt has a low activity for isopropanol electrooxidation.…”