Document Type

Theses, Ph.D

Rights

This item is available under a Creative Commons License for non-commercial use only

Publication Details

Thesis submitted for examination for the award of Doctor of Philosophy (PhD), School of Chemical and Pharmaceutical Sciences, Dublin Institute of Technology, Kevin Street, Dublin 8, 2016.

Abstract

The anodic reaction of the Direct Ethanol Fuel Cell has been studied with various catalysts such as electrodeposited platinum, palladium, nickel and gold electrodes. The mechanism of bimetallic catalysts was used to reduce the platinum content needed for ethanol oxidation. The effects of increased temperature, ethanol concentration, electrolyte pH and scan rate have been examined. The impact of different carbon surfaces such as carbon ink, carbon paper and commonly used Vulcan XC72 have also been analysed in order to determine the optimum conditions for the EOR in a fuel cell.

Electrochemical methods were used to analyse catalyst performance such as cyclic voltammetry, linear sweep voltammetry, current/time plots, chronocoulometry and Tafel analysis. Tafel slopes were calculated from 250 mV/decade up to 550 mV/decade. In addition, the best performing catalysts, Pt75%Pd25% and Pt90%Ni10% were used in a model fuel cell with an air cathode where power between 30 and 100 μW was obtained. Moreover, selected catalysts were analysed by Electrochemical Impedance Spectroscopy, circuit modelling, Scanning Electron Microscopy and elemental mapping.

Electrodeposition was found to be a quick, reliable and reproducible method for catalyst deposition and 120 mC/cm2 or 0.12 mg/cm2 of precious metal was typically used for analysis. The carbon substrate was found to be a major limitation due to induction periods for charge collection measured by chronocoulometry and its high resistance of 800-1000 Ω.cm2 measured by Impedance Spectroscopy.

DOI

10.21427/D76J1Z

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