Multi-component Platinum Group Metals for the methanol electro-oxidation process
Javu, Bulelwa Patricia
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The purpose of this study was to develop a high performance-lower cost catalyst to be applied in Direct Methanol Fuel Cells (DMFC). The study also aimed to prepare plurimetallic supported platinum (Pt), platinum-ruthenium (PtRu), platinum-ruthenium-vanadium (PtRuV) and platinum ruthenium-vanadium-iron (PtRuVFe) upon multi-walled carbon nanotube (MWCNT) as well as upon multiwalled carbon nanotube-titanium oxide (MWCNT/TiO2) supports. Platinum is very active but prone to poisoning by carbon monoxide (CO), which may be present in the fuel used in fuel cells. The focus on the use of methanol was because of its better reaction kinetics, and better performance in direct methanol fuel cells (DMFC) better than proton exchange membrane fuel cell (PEMFC). When Pt is alloyed with another platinum group metals (PGM) the alloying decreases the over-potential for reactions critical in the fuel cells. Proton exchange membrane fuel cell (PEMFC) performance may be improved at low metal loading, when supported pluri-metallic catalysts are applied since the trimetallic catalysts may promote high catalyst utilisation. In practice, DMFC require electrodes with a Pt loading to achieve acceptance fuel cell (FC) power performance. The aim of this study was therefore the reduction of the catalyst loading through further improvement of mass activity of Pt based catalysts by partial substitution of the noble metal/metals, and the use of a carbon support that will provide high surface area, good electrical conductivity and high stability. MWCNT supported pluri-metallic (PtRuVFe,) and bimetallic (PtRu) nanoparticles possessed characteristic of increased surface area, improved electron transfer rate, enhance electro-catalytic activity and promoted stability.