Calculations of oxygen reduction reaction on nanoparticles

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Title: Calculations of oxygen reduction reaction on nanoparticles
Author: Tang, Wenjie, 1982-
Abstract: Proton exchange membrane fuel cells are attractive power sources because they are highly efficient and do not pollute the environment . However , the use of Pt -based catalysts in present fuel cell technologies is not optimal : Pt is rare and expensive , and even the best commercial Pt cathodes have high overpotentials due to slow oxygen reduction kinetics . As a result , much effort has gone toward developing cheaper , more effective catalysts . Nanoparticles are attractive because they have different catalytic properties than analogous bulk systems , require less material , and have tunable reactivities based on their composition and size . It is important to perform detailed studies of nanoparticle catalysts since composition and size effects are poorly understood . Computational simulations of such materials can provide useful insights and potentially aid in the design of new catalysts . Here , I examine composition and size effects in nanoparticle catalysts using computational methods . Two bimetallic systems are investigated to explore composition effects : Pd -shell particles with several different core metals , and Pd /Cu random alloy particles . Depending on how the two metals are mixed (core -shell or random alloy ) , charge transfer and strain due to alloying are found to have different contributions to the catalytic activity . Size effects are studied for pure Pt particles , where corner and edge sites are found to play an important role . The binding geometries of molecular oxygen to corner and edge sites lead to peroxide formation instead of water on small Pt particles . Results form these calculations can provide useful information for designing novel catalysts in the future . By changing the composition and /or size of nanoparticles in the proper way , the interaction between the adsorbate and catalyst can be optimized , and better catalysts can be obtained .
URI: http : / /hdl .handle .net /2152 /ETD -UT -2010 -05 -775
Date: 2010-09-16


Calculations of oxygen reduction reaction on nanoparticles. Doctoral dissertation, University of Texas at Austin. Available electronically from http : / /hdl .handle .net /2152 /ETD -UT -2010 -05 -775 .

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