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Development of Metalloenzyme Dioxyge...

Agbo, Peter Chukwudi Ifeanychukwu.

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Development of Metalloenzyme Dioxygen Reduction Cathodes.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Development of Metalloenzyme Dioxygen Reduction Cathodes./
Author:	Agbo, Peter Chukwudi Ifeanychukwu.
Description:	152 p.
Notes:	Source: Dissertation Abstracts International, Volume: 76-03(E), Section: B.
Contained By:	Dissertation Abstracts International76-03B(E).
Subject:	Inorganic chemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3642397
ISBN:	9781321291988

Development of Metalloenzyme Dioxygen Reduction Cathodes.
Agbo, Peter Chukwudi Ifeanychukwu.

Development of Metalloenzyme Dioxygen Reduction Cathodes. - 152 p.

Source: Dissertation Abstracts International, Volume: 76-03(E), Section: B.

Thesis (Ph.D.)--California Institute of Technology, 2015.

This item must not be sold to any third party vendors.

The prime thrust of this dissertation is to advance the development of fuel cell dioxygen reduction cathodes that employ some variant of multicopper oxidase enzymes as the catalyst. The low earth-abundance of platinum metal and its correspondingly high market cost has prompted a general search amongst chemists and materials scientists for reasonable alternatives to this metal for facilitating catalytic dioxygen reduction chemistry. The multicopper oxidases (MCOs), which constitute a class of enzyme that naturally catalyze the reaction O2 + 4H+ + 4e- → 2H2O, provide a promising set of biochemical contenders for fuel cell cathode catalysts. In MCOs, a substrate reduces a copper atom at the type 1 site, where charge is then transferred to a trinuclear copper cluster consisting of a mononuclear type 2 or "normal copper" site and a binuclear type 3 copper site. Following the reduction of all four copper atoms in the enzyme, dioxygen is then reduced to water in two two-electron steps, upon binding to the trinuclear copper cluster. We identified an MCO, a laccase from the hyperthermophilic bacterium Thermus thermophilus strain HB27, as a promising candidate for cathodic fuel cell catalysis. This protein demonstrates resilience at high temperatures, exhibiting no denaturing transition at temperatures high as 95 C, conditions relevant to typical polymer electrolyte fuel cell operation.

ISBN: 9781321291988Subjects--Topical Terms:

3173556
Inorganic chemistry.

Development of Metalloenzyme Dioxygen Reduction Cathodes.
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020 $a 9781321291988
035 $a (MiAaPQ)AAI3642397
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100 1 $a Agbo, Peter Chukwudi Ifeanychukwu. $3 3181258
245 1 0 $a Development of Metalloenzyme Dioxygen Reduction Cathodes.
300 $a 152 p.
500 $a Source: Dissertation Abstracts International, Volume: 76-03(E), Section: B.
500 $a Advisers: Harry B. Gray; James R. Heath.
502 $a Thesis (Ph.D.)--California Institute of Technology, 2015.
506 $a This item must not be sold to any third party vendors.
520 $a The prime thrust of this dissertation is to advance the development of fuel cell dioxygen reduction cathodes that employ some variant of multicopper oxidase enzymes as the catalyst. The low earth-abundance of platinum metal and its correspondingly high market cost has prompted a general search amongst chemists and materials scientists for reasonable alternatives to this metal for facilitating catalytic dioxygen reduction chemistry. The multicopper oxidases (MCOs), which constitute a class of enzyme that naturally catalyze the reaction O2 + 4H+ + 4e- → 2H2O, provide a promising set of biochemical contenders for fuel cell cathode catalysts. In MCOs, a substrate reduces a copper atom at the type 1 site, where charge is then transferred to a trinuclear copper cluster consisting of a mononuclear type 2 or "normal copper" site and a binuclear type 3 copper site. Following the reduction of all four copper atoms in the enzyme, dioxygen is then reduced to water in two two-electron steps, upon binding to the trinuclear copper cluster. We identified an MCO, a laccase from the hyperthermophilic bacterium Thermus thermophilus strain HB27, as a promising candidate for cathodic fuel cell catalysis. This protein demonstrates resilience at high temperatures, exhibiting no denaturing transition at temperatures high as 95 C, conditions relevant to typical polymer electrolyte fuel cell operation.
520 $a In Chapter I of this thesis, we discuss initial efforts to physically characterize the enzyme when operating as a heterogeneous cathode catalyst. Following this, in Chapter II we then outline the development of a model capable of describing the observed electrochemical behavior of this enzyme when operating on porous carbon electrodes. Developing a rigorous mathematical framework with which to describe this system had the potential to improve our understanding of MCO electrokinetics, while also providing a level of predictive power that might guide any future efforts to fabricate MCO cathodes with optimized electrochemical performance. In Chapter III we detail efforts to reduce electrode overpotentials through site-directed mutagenesis of the inner and outer-sphere ligands of the Cu sites in laccase, using electrochemical methods and electronic spectroscopy to try and understand the resultant behavior of our mutant constructs. Finally, in Chapter IV, we examine future work concerning the fabrication of enhanced MCO cathodes, exploring the possibility of new cathode materials and advanced enzyme deposition techniques.
590 $a School code: 0037.
650 4 $a Inorganic chemistry. $3 3173556
650 4 $a Biophysics. $3 518360
650 4 $a Organic chemistry. $3 523952
690 $a 0488
690 $a 0786
690 $a 0490
710 2 $a California Institute of Technology. $b Chemistry. $3 2096080
773 0 $t Dissertation Abstracts International $g 76-03B(E).
790 $a 0037
791 $a Ph.D.
792 $a 2015
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3642397