Sol-Gel Based Silica Electrodes for Inorganic Membrane DMFCs
Author(s) -
Hyea Kim
Publication year - 2009
Publication title -
the electrochemical society interface
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.568
H-Index - 46
eISSN - 1944-8783
pISSN - 1064-8208
DOI - 10.1149/2.f09094if
Subject(s) - materials science , electrode , membrane , sol gel , chemical engineering , nanotechnology , chemistry , engineering , biochemistry
However, theDMFC performancewasunstablebecause thepolymer-basedionomerusedin thecatalystinkwasincompatible withtheglassmembrane. The coefficientofthermalexpansion mismatchbetweentheelectrode andmembranecontributedtohigh contactresistance. Therearelong- termreliabilityissueswiththewater- rich, polymerionomersoakinginthe aqueousmethanolofapassiveDMFC. Inthisproject, electrodesbased onglass-basedionomerswere investigated. Platinum-ruthenium glasselectrodes (PtRu/C-SiO2) were preparedbyincorporatingthe PtRu/Cnanoparticlesintoasilica- basedmatrix. TheSiO2 matrixwas synthesizedthroughthesol-gel reactionof 3-(trihydroxysilyl)-1- propanesulfonicacid (3TPS) and 3-glycidoxypropyltrimethoxysilane (GPTMS). Thestructuresof 3TPS andGPTMSareshowninFig. 1. The sulfonicacidgroupin 3TPSprovides protonconductivityinthecatalyst layer.Thethreehydroxylgroupsofthe 3TPSreactwithwaterandcondense toformasilicamatrixencapsulating thecatalystinthematrix. Theepoxy contentoftheGPTMSimprovedthe mechanicalpropertiesoftheelectrode bycrosslinkingwiththesilicon dioxidematrix. Thesizeanddistributionofthe PtRu/Cparticleswascontrolledby changingthemicrostructureand propertiesofthegelmatrix. The effectofgelationtime, molefraction ofreactantswithinthesol, curing temperature,andglassionomercontent wereinvestigated. Theadhesionof thecatalystlayeronthemembrane, electrochemicalactivityformethanol oxidation, anddecreasemethanol cross-overthroughthemembrane wereinvestigated. Theoptimumglass electrodewascomposedof 90 mol% 3TPSand 10 mol% GPTMSandthe catalyst-to-glassratiowas1:5.The3TPS
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