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Electro-Catalysis of Oxygen Reduction on Platinum-Bismuth Alloy Nanoparticles and a Study of Nafion Ionomer Impact.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Electro-Catalysis of Oxygen Reduction on Platinum-Bismuth Alloy Nanoparticles and a Study of Nafion Ionomer Impact.
作者:	Fang, Junchuan.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, 2021
面頁冊數:	235 p.
附註:	Source: Dissertations Abstracts International, Volume: 83-06, Section: B.
Contained By:	Dissertations Abstracts International83-06B.
標題:	Chemical engineering.
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28890273
ISBN:	9798492757243

Electro-Catalysis of Oxygen Reduction on Platinum-Bismuth Alloy Nanoparticles and a Study of Nafion Ionomer Impact.
Fang, Junchuan.

Electro-Catalysis of Oxygen Reduction on Platinum-Bismuth Alloy Nanoparticles and a Study of Nafion Ionomer Impact. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 235 p.

Source: Dissertations Abstracts International, Volume: 83-06, Section: B.

Thesis (Ph.D.)--University of Cincinnati, 2021.

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

In this dissertation, Bi is alloyed with Pt to improve the ORR performance. The sluggish ORR kinetics is a major barrier for fuel cells, thus motivating research aimed at developing electro-catalysts with enhanced ORR performance and understanding the impact of Nafion on ORR kinetics and oxygen diffusion. Dimethyl ether (DME) is investigated as a less toxic fuel alternative to methanol. Synthesis formulations are varied to understand the role of electro-catalyst structure on DMEOR activity.In the first section, free-standing Pt2Bi nanoplatelets (PtBi NP) are demonstrated with superior ORR performance and excellent long-term stability. At 0.9V, PtBi NP can achieve a specific activity of 18.08 Am-2Pt, 7.1 times higher than that of commercial Pt/C, and show a slight degradation in ORR performance without ECSA loss after accelerated durability test (ADT). This is attributed to the incorporated Bi atoms, optimizing the Pt d-band center, weakening the oxygen binding energy and reducing the Pt dissolution. Acid leaching is used to prepare electro-catalyst for real fuel cell test. RDE shows promising ORR performance. However, poor operating fuel cell performance is obtained under gas-feed conditions and is ascribed to poor oxygen transport through the ionomer/water layers present on the less wettable alloy surface relative to Pt/C. The second section describes a co-reduction synthesis of carbon-supported PtBi spherical nanoparticles (PtBi SP) with enhanced ORR activity and stability. At 0.9V, PtBi SP exhibits enhanced specific activity (about 4.7 times higher than that of Pt/C) and improved durability by reflecting little loss in ECSA and ORR activity after ADT. This is ascribed to electronic and synergistic ensemble effects associated with the incorporation of Bi atoms into the Pt lattice comparable to those of the PtBi NP. However, while qualitatively similar, these effects are much less prominent in the case of PtBi SP, which is evident in the lower ORR specific activity.Nafion deposition on the electro-catalyst surface and the impact on oxygen diffusion are studied in the third section. Macroscopic poly Pt electrode, commercial Pt/C and PtBi NP are employed as substrates while the deposition of different Nafion loadings is investigated. Resorcinol is also introduced as a polyelectrolyte structure modifier. CV and RDE are utilized to characterize oxygen transport behavior. Increased Nafion loading yields greater oxygen permeability due to solubility while bonding to the surface impedes ORR activity. Resorcinol is found to mitigate such bonding on macroscopic surfaces at lower potentials but reacts with the surface and interferes with ORR activity at higher potentials. Optimization of the relative amount of Nafion and resorcinol is needed in highly dispersed nanoparticle systems.The final section explores the DMEOR performance on PtBi SP synthesis conditions. Electro-catalysts synthesized with more Sn stabilizer exhibit substantial agglomeration with correspondingly lower ECSA and poorer DMEOR activity and durability. Increasing the rest period in the synthesis solution prior to supporting the nanoparticles on carbon is found to show similar degradation in DMEOR performance, suggesting comparable agglomeration. However, increasing the synthesis time is found to restore performance. Optimum synthesis conditions are here reported.

ISBN: 9798492757243Subjects--Topical Terms:

206267
Chemical engineering.
Subjects--Index Terms:

Fuel cells

Electro-Catalysis of Oxygen Reduction on Platinum-Bismuth Alloy Nanoparticles and a Study of Nafion Ionomer Impact.
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500 $a Source: Dissertations Abstracts International, Volume: 83-06, Section: B.
502 $a Thesis (Ph.D.)--University of Cincinnati, 2021.
506 $a This item must not be sold to any third party vendors.
520 $a In this dissertation, Bi is alloyed with Pt to improve the ORR performance. The sluggish ORR kinetics is a major barrier for fuel cells, thus motivating research aimed at developing electro-catalysts with enhanced ORR performance and understanding the impact of Nafion on ORR kinetics and oxygen diffusion. Dimethyl ether (DME) is investigated as a less toxic fuel alternative to methanol. Synthesis formulations are varied to understand the role of electro-catalyst structure on DMEOR activity.In the first section, free-standing Pt2Bi nanoplatelets (PtBi NP) are demonstrated with superior ORR performance and excellent long-term stability. At 0.9V, PtBi NP can achieve a specific activity of 18.08 Am-2Pt, 7.1 times higher than that of commercial Pt/C, and show a slight degradation in ORR performance without ECSA loss after accelerated durability test (ADT). This is attributed to the incorporated Bi atoms, optimizing the Pt d-band center, weakening the oxygen binding energy and reducing the Pt dissolution. Acid leaching is used to prepare electro-catalyst for real fuel cell test. RDE shows promising ORR performance. However, poor operating fuel cell performance is obtained under gas-feed conditions and is ascribed to poor oxygen transport through the ionomer/water layers present on the less wettable alloy surface relative to Pt/C. The second section describes a co-reduction synthesis of carbon-supported PtBi spherical nanoparticles (PtBi SP) with enhanced ORR activity and stability. At 0.9V, PtBi SP exhibits enhanced specific activity (about 4.7 times higher than that of Pt/C) and improved durability by reflecting little loss in ECSA and ORR activity after ADT. This is ascribed to electronic and synergistic ensemble effects associated with the incorporation of Bi atoms into the Pt lattice comparable to those of the PtBi NP. However, while qualitatively similar, these effects are much less prominent in the case of PtBi SP, which is evident in the lower ORR specific activity.Nafion deposition on the electro-catalyst surface and the impact on oxygen diffusion are studied in the third section. Macroscopic poly Pt electrode, commercial Pt/C and PtBi NP are employed as substrates while the deposition of different Nafion loadings is investigated. Resorcinol is also introduced as a polyelectrolyte structure modifier. CV and RDE are utilized to characterize oxygen transport behavior. Increased Nafion loading yields greater oxygen permeability due to solubility while bonding to the surface impedes ORR activity. Resorcinol is found to mitigate such bonding on macroscopic surfaces at lower potentials but reacts with the surface and interferes with ORR activity at higher potentials. Optimization of the relative amount of Nafion and resorcinol is needed in highly dispersed nanoparticle systems.The final section explores the DMEOR performance on PtBi SP synthesis conditions. Electro-catalysts synthesized with more Sn stabilizer exhibit substantial agglomeration with correspondingly lower ECSA and poorer DMEOR activity and durability. Increasing the rest period in the synthesis solution prior to supporting the nanoparticles on carbon is found to show similar degradation in DMEOR performance, suggesting comparable agglomeration. However, increasing the synthesis time is found to restore performance. Optimum synthesis conditions are here reported.
590 $a School code: 0045.
650 4 $a Chemical engineering. $3 206267
653 $a Fuel cells
653 $a Oxygen reduction reaction
653 $a Platinum-bismuth alloy
653 $a Nafion impact
653 $a Dimethyl ether oxidation reaction
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710 2 $a University of Cincinnati. $b Engineering and Applied Science: Chemical Engineering. $3 915892
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792 $a 2021
793 $a English
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