Pristine and graphitized-MWCNTs as durable cathode-catalyst supports for PEFCs

Selvaganesh, Vinod S and Sridhar, P and Pitchumani, S and Shukla, AK (2014) Pristine and graphitized-MWCNTs as durable cathode-catalyst supports for PEFCs. In: JOURNAL OF SOLID STATE ELECTROCHEMISTRY, 18 (5). pp. 1291-1305.

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Abstract

Long-term deterioration in the performance of PEFCs is attributed largely to reduction in active area of the platinum catalyst at cathode, usually caused by carbon-support corrosion. Multi-walled carbon-nanotubes (MWCNTs) as cathode-catalyst support are found to enhance long-term stability of platinum catalyst (Pt) in relation to non-graphitic carbon. In addition, highly graphitic MWCNTs (G-MWCNTs) are found to be electrochemically more stable than pristine MWCNTs. This is because graphitic-carbon-supported-Pt (Pt/MWCNTs) cathodes exhibit higher resistance to carbon corrosion in-relation to non-graphitic-carbon-supported-Pt (Pt/C) cathodes in PEFCs during accelerated stress-test (AST) as evidenced by chronoamperometry and carbon dioxide studies. The corresponding change in electrochemical surface area (ESA), cell performance, and charge-transfer resistance are monitored through cyclic voltammetry, cell polarization, and impedance measurements, respectively. The extent of crystallinity, namely amorphous or graphitic nature of the three supports, is examined by Raman spectroscopy. X-ray diffraction and transmission electron microscopy studies both prior and after AST suggest lesser deformation in catalyst layer and catalyst particles for Pt/G-MWCNTs and Pt/MWCNTs cathodes in relation to Pt/C cathodes, reflecting that graphitic carbon-support resists carbon corrosion and helps mitigating aggregation of Pt particles. It is also found that with increasing degree of graphitization, the electrochemical stability for MWCNTs increases due to the lesser surface defects.

Item Type:	Journal Article
Publication:	JOURNAL OF SOLID STATE ELECTROCHEMISTRY
Publisher:	SPRINGER
Additional Information:	Copyright for this article belongs to the SPRINGER, 233 SPRING ST, NEW YORK, NY 10013 USA
Keywords:	Accelerated stress test; Carbon corrosion; Cathode catalyst; Degradation; Electrochemical surface area; Membrane electrode assembly
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	24 Jun 2014 07:22
Last Modified:	24 Jun 2014 07:22
URI:	http://eprints.iisc.ac.in/id/eprint/49318

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