Development of anode catalysts for direct alcohol fuel cells

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Title: Development of anode catalysts for direct alcohol fuel cells
Author: Lee, Eungje
Abstract: Direct alcohol fuel cells (DAFC ) are attracting considerable interest to meet a variety of energy needs as they offer higher efficiency with less pollution compared to other conventional energy -conversion devices . However , the sluggish alcohol oxidation reaction kinetics and durability problems of the conventional Pt -Ru anode catalyst hamper the commercialization of the DAFC systems . With an aim to overcome these problems , there have been intensive efforts to alloy Pt -Ru with other metals . Although such strategies have led to some enhancement in activity , the durability problem caused by the instability of Ru could still not be alleviated . In this regard , this dissertation focuses on the development of non -Ru electrocatalysts with high activity and durability for DAFC applications . First , Ru -free , Pt -based bimetallic electrocatalysts for methanol oxidation reaction (MOR ) were studied . Particularly , Pt -Sn and Pt -CeO₂ catalysts were synthesized , respectively , by a polyol method and a one -step reverse microemulsion (RME ) method . The prepared samples are investigated for phase and morphological evaluations by various material -characterization techniques . Cyclic voltammetry and accelerated durability tests revealed that these alternative catalysts have much higher stability with a catalytic activity for MOR comparable to that of Pt -Ru . In the case of Pt -CeO₂ , an improved particle morphology is obtained by the RME synthesis , and the advantage of the RME method is reflected by a higher catalytic activity in comparison to that of Pt -CeO₂ synthesized by the conventional synthesis method . It has been known that Pt -Sn is better than Pt -Ru for ethanol oxidation reaction (EOR ) , and the direct ethanol fuel cells (DEFC ) employing Pt -Sn as the anode catalyst have better durability than the DMFC system employing a Pt -Ru anode catalyst . Therefore , this dissertation then focused on the enhancement of the catalytic activity for EOR by incorporating a third metal M to the Pt -Sn catalyst . Following the synthesis and characterization of the Pt -Sn -M (M = Mo and Pd ) alloys , the effect of M on the enhanced catalytic activity of Pt -Sn -M is presented . The activity enhancement of the above catalysts is based on the promoting effect of the second or third elements added to Pt . However , in the final chapter of this dissertation , the activity enhancement of Pt nanoparticle itself through the formation of low energy surfaces is investigated . Carbon -supported Pt nanoparticles are synthesized in mixed water -ethylene glycol solvent , and the positive effect of the mixed solvent on both the morphology and surface structure of the Pt nanoparticles for COad oxidation is discussed .
URI: http : / /hdl .handle .net /2152 /ETD -UT -2010 -08 -1708
Date: 2010-12-09


Development of anode catalysts for direct alcohol fuel cells. Doctoral dissertation, University of Texas at Austin. Available electronically from http : / /hdl .handle .net /2152 /ETD -UT -2010 -08 -1708 .

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