Proton exchange membrane (PEM) fuel cell technology is promissing alternative solution to today&rsquo / s energy concerns providing clean environment and efficient system. Decreasing platinum (Pt) content of fuel cell is one of the main goals to reduce high costs of fuel cell technology in the way of commercialization. In this target, porous carbons provide an alternative solution as a support material for fuel cell electrocatalysts. It is also essential to increase surface area of carbon support material to have well dispersion of the Pt nanoparticles. The aim of this thesis is to synthesize mesoporous carbon supports named as hollow core mesoporous shell (HCMS) carbon and prepare their corresponding electrocatalysts with platinum impregnation method.
HCMS carbon supports were synthesized by using two different carbon sources.
As a first approach, phenol/paraformaldehyde couples were used and carbon source exhibited 1053 m 2 /g BET surface area and 1.046 nm BJH adsorption pore diameter.
Second approach was to use divinylbenzene (DVB) as a carbon source with an initiator named as azo bis isobuytronitrile (AIBN) differing synthesis criteria. It is observed that using AIBN/DVB, pore sizes increased up to 3.44 nm.
Platinum impregnation was conducted by microwave irradiation method using hydrogen hexachloroplatinate (IV) hydrate as a platinum precursor. The first achievement was to increase platinum loading up to 44 wt % on commercial Vulcan
XC 72 by using ethylene glycol as a reducing agent. Using different reducing agents such as hydrazine, sodium borohydrate with a combination of ethylene glycol, platinum loading reached up to 34 wt % on HCMS carbon support. Accordingly, 34 wt %, 32 wt % and 28 wt % Pt/HCMS carbon supported electrodes preparation was achieved. The sizes of the platinum nanoparticles were calculated by XRD analysis as 4 nm, 4.2 nm and 4.5 nm for 28 wt %, 32 wt % and 34 wt % Pt/HCMS carbon supported electrodes respectively. Characterizations of catalysts were performed by ex situ (N 2 adsorption, TGA, SEM, TEM and Cyclic Voltammetry) and in situ (PEMFC tests) analysis.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12612376/index.pdf |
| Date | 01 September 2010 |
| Creators | Guvenatam, Burcu |
| Contributors | Eroglu, Inci |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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