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Electroless deposition methods to sy...

University of South Carolina., Chemical Engineering.

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Electroless deposition methods to synthesize fuel cell catalysts: Methodology and structural characteristics.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Electroless deposition methods to synthesize fuel cell catalysts: Methodology and structural characteristics./
Author:	Beard, Kevin.
Description:	291 p.
Notes:	Advisers: John W. Van Zee; John R. Monnier.
Contained By:	Dissertation Abstracts International70-02B.
Subject:	Chemistry, Inorganic. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3344668
ISBN:	9781109032031

Electroless deposition methods to synthesize fuel cell catalysts: Methodology and structural characteristics.
Beard, Kevin.

Electroless deposition methods to synthesize fuel cell catalysts: Methodology and structural characteristics. - 291 p.

Advisers: John W. Van Zee; John R. Monnier.

Thesis (Ph.D.)--University of South Carolina, 2009.

Electroless deposition (ED) is a preparative technique for the synthesis of bimetallic supported catalysts wherein a reducible metal salt is deposited on specific sites of a catalyst surface using a catalytically-activated chemical reducing agent. This dissertation describes the use of ED to prepare several families of carbon-supported Pt-M (M = Rh, Pd, and Co) bimetallic catalysts having improved physical and performance characteristics for fuel cell applications.

ISBN: 9781109032031Subjects--Topical Terms:

517253
Chemistry, Inorganic.

Electroless deposition methods to synthesize fuel cell catalysts: Methodology and structural characteristics.
LDR:04772nmm 2200373 a 45 001 886655
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020 $a 9781109032031
035 $a (UMI)AAI3344668
035 $a AAI3344668
040 $a UMI $c UMI
100 1 $a Beard, Kevin. $3 1058360
245 1 0 $a Electroless deposition methods to synthesize fuel cell catalysts: Methodology and structural characteristics.
300 $a 291 p.
500 $a Advisers: John W. Van Zee; John R. Monnier.
500 $a Source: Dissertation Abstracts International, Volume: 70-02, Section: B, page: 1172.
502 $a Thesis (Ph.D.)--University of South Carolina, 2009.
520 $a Electroless deposition (ED) is a preparative technique for the synthesis of bimetallic supported catalysts wherein a reducible metal salt is deposited on specific sites of a catalyst surface using a catalytically-activated chemical reducing agent. This dissertation describes the use of ED to prepare several families of carbon-supported Pt-M (M = Rh, Pd, and Co) bimetallic catalysts having improved physical and performance characteristics for fuel cell applications.
520 $a Firstly, the ED of Pt on Rh/C is studied to understand the effect of synthesis parameters (reducing agent and stabilizing agent concentrations, pH of ED bath, and precursor catalyst loading) on rate and extent of Pt deposition. There is a linear relationship between the rate and extent of Pt deposition with concentration of the reducing agent and precursor catalyst loading; the stabilizing agent concentration has little effect on rate and only a modest effect on extent of Pt ED. Lastly, the extent of Pt ED shows a maximum with respect to the pH of the ED bath. TEM analyses of the Rh/C and Pt-Rh/C samples indicate that higher weight loadings of Rh result in more similar-sized particles rather than particle growth. Deposition of only 6--7% Pt gives a Pt surface area similar to that for a commercial 20% Pt/C catalyst.
520 $a Next, after modification of the carbon support and selection of a proper Pd salt, a series of Pt-Pd/C catalysts was prepared by electroless deposition of Pt. Analysis by TEM confirms that ED of Pt on the smaller Pd particles results in smaller overall Pt-Pd/C particles compared to Pt-Rh/C and commercial 20% Pt/C. The structure of the Pt-Pd particles was also investigated by X-ray photoelectron spectroscopy (XPS); results suggest that Pt and Pd form a near-surface solid solution, or alloy, particle and not a core/shell particle. Despite favorable particle size and Pt dispersion characteristics, the Pt-Pd/C oxygen reduction reaction (ORR) activity, measured by rotating disk electrode (RDE), remained comparable to the commercial 20% Pt/C catalyst. The alloy composition of the Pt-Pd surface may be linked to the reason why ORR activity was the same as that for a monometallic Pt/C catalyst.
520 $a Finally, Pt has been electrolessly deposited on a Co/C catalyst. HRTEM images indicate that ED of Pt on Co results in formation of Co core/Pt shell particles which have the potential of protecting the Co from leaching in acidic environments and increasing the ORR activity of the Pt surface. Temperature programmed reduction (TPR) studies indicate that one complete monolayer of Pt on Co is formed at a Pt : Co atomic ratio of approximately 0.1. However, acid treatment in 0.3M H2SO4 for Pt-Co/C bimetallic compositions with Pt : Co atomic ratios > 0.1 show significant Co leaching, although leaching is lower than for pure Co/C catalysts. HRTEM and EDX analyses indicate that Pt does deposit layer-by-layer to produce complete encapsulation of Co for "small" (< 6 nm) Co particles, but the formation of three dimensional aggregates of Pt is favored on the surfaces of "large" (>10 nm) Co particles. ORR, determined by RDE, indicates that Pt site specific activity of Pt-Co/C is much greater than commercial Pt/C while Pt mass specific activity of Pt-Co/C is approximately equal to commercial Pt/C due to the existence of the three dimensional Pt aggregates on the large Co particles. Future efforts should focus on the formation of uniformly small (< 6 nm) Co particles to favor the formation of fully encapsulated Co core/Pt shell particles.
590 $a School code: 0202.
650 4 $a Chemistry, Inorganic. $3 517253
650 4 $a Engineering, Chemical. $3 1018531
690 $a 0488
690 $a 0542
710 2 $a University of South Carolina. $b Chemical Engineering. $3 1029807
773 0 $t Dissertation Abstracts International $g 70-02B.
790 $a 0202
790 1 0 $a Buggy, James $e committee member
790 1 0 $a Chen, Donna $e committee member
790 1 0 $a Monnier, John R., $e advisor
790 1 0 $a Van Zee, John W., $e advisor
790 1 0 $a Weidner, John $e committee member
790 1 0 $a Williams, Christopher T. $e committee member
791 $a Ph.D.
792 $a 2009
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3344668