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Durable Fuel Cell Electrocatalysts for Energy Conversion.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Durable Fuel Cell Electrocatalysts for Energy Conversion./
作者:	Zhang, Zishuai.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2019,
面頁冊數:	242 p.
附註:	Source: Dissertations Abstracts International, Volume: 82-10, Section: B.
Contained By:	Dissertations Abstracts International82-10B.
標題:	Fuel cells. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28254573
ISBN:	9798708700575

Durable Fuel Cell Electrocatalysts for Energy Conversion.
Zhang, Zishuai.

Durable Fuel Cell Electrocatalysts for Energy Conversion. - Ann Arbor : ProQuest Dissertations & Theses, 2019 - 242 p.

Source: Dissertations Abstracts International, Volume: 82-10, Section: B.

Thesis (Ph.D.)--McGill University (Canada), 2019.

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

Electrocatalysts play an important avenue in clean and efficient energy conversion. Of the many electrocatalytic processes, the oxygen reduction reaction (ORR) attracts increasing attention due to its widespread importance in electrochemical cells. One of the most important applications is in proton-exchange membrane fuel cells (PEMFCs), which are considered as a promising power generation system because of its low operating temperature (70-90 ˚C), sustainable energy sources (hydrogen) and high energy efficiency. ORR is a key half reaction that takes place at the cathode with sluggish kinetics and requires noble metal (e.g. platinum)-based electrocatalysts to increase the reaction rate to attain practically usable levels. High cost and poor durability are major drawbacks of the commercial platinum on carbon (Pt/C) catalyst, and the corrosion of the carbon supports is considered one of the main reasons for the loss of expensive Pt, resulting in loss of performance of PEMFC. Therefore, more corrosion resistant, electrochemically stable and lowcost supports are highly desired for PEMFCs' improved performance.Methanol oxidation reaction (MOR) is an anodic half reaction occurs at anodes of methanol fuel cells. Pt/C catalyst is also commonly used for that reaction. This thesis attempts to rationally design and synthesize various different nanostructured alternatives to carbon black for ORR and MOR. Graphene, a high conductive and stable two-dimensional carbon support, was successfully exfoliated electrochemically with little defects. Platinum (Pt) nanoparticles were deposited on graphene via double-pulse deposition technique. The catalyst was demonstrated to be highly efficient for MOR with a 920 mA/mg forward current density.Durable carbon nanotube (CNT) microspheres were synthesized through a facile and scalable ultrasonic bonding method without any binder or surfactant. The CNT microspheres with electrodeposited Pt were showcased as efficient ORR catalyst supports which showed no degradation after 12, 000 cycles (26.6 h). Furthermore, a soluble acicular calcium carbonate (aragonite, diameter 100 nm; length 800 nm) was used to created connected porosity in the microspheres to improve the mass transfer as the thickness increases. As for the ORR catalysis performance, the Pt decorated microspheres with macropores was 3.4 times higher (specific activity at 0.9V vs RHE) than non-macroporous microspheres with the identical Pt loading.Besides carbon-based supports, TiC was investigated as a potential carbon alternative due to its metallic electrical conductivity and excellent corrosion resistance. A cobalt oxide shell with high ORR activity was deposited onto TiC to improve its stability at high potential. We demonstrated that the oxide anchored Pt on TiC catalysts exhibited excellent durability (~100% catalytic activity remained at 0.1M KOH, and ~92% catalytic activity remained at 0.1M HClO4 after 16.7 h) compared to the Pt/C (~50% remained in both alkaline and acidic solutions). As assessed by transmission electron microscope (TEM), no significant Pt detachment or agglomeration was observed in oxide anchored catalysts, while heavily agglomeration has occurred to Pt/C.Hematene, two-dimensional layer of hematite (Fe2O3), has recently been exfoliated by means of liquid exfoliation. As the biodegradable metal, Fe-based materials attracts lots of attentions due to their ability to be entirely dissolved and cleared from the body. Electronics comprised of biodegradable metals can be programmed to degrade after the implantation. Here, we fabricated potentially biodegradable electrodes by using Au and hematene for glucose oxidation. It showed 9.5 mA/mgAu oxidation current density at the potential of 0.6V (vs. RHE), and high stability during the continuous cell cycling. Additionally, the prepared catalyst exhibited short response time and linear calibration range.

ISBN: 9798708700575Subjects--Topical Terms:

645135
Fuel cells.
Subjects--Index Terms:

Oxygen reduction reaction

Durable Fuel Cell Electrocatalysts for Energy Conversion.
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100 1 $a Zhang, Zishuai. $3 3690297
245 1 0 $a Durable Fuel Cell Electrocatalysts for Energy Conversion.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2019
300 $a 242 p.
500 $a Source: Dissertations Abstracts International, Volume: 82-10, Section: B.
500 $a Advisor: Barralet, Jake.
502 $a Thesis (Ph.D.)--McGill University (Canada), 2019.
506 $a This item must not be sold to any third party vendors.
520 $a Electrocatalysts play an important avenue in clean and efficient energy conversion. Of the many electrocatalytic processes, the oxygen reduction reaction (ORR) attracts increasing attention due to its widespread importance in electrochemical cells. One of the most important applications is in proton-exchange membrane fuel cells (PEMFCs), which are considered as a promising power generation system because of its low operating temperature (70-90 ˚C), sustainable energy sources (hydrogen) and high energy efficiency. ORR is a key half reaction that takes place at the cathode with sluggish kinetics and requires noble metal (e.g. platinum)-based electrocatalysts to increase the reaction rate to attain practically usable levels. High cost and poor durability are major drawbacks of the commercial platinum on carbon (Pt/C) catalyst, and the corrosion of the carbon supports is considered one of the main reasons for the loss of expensive Pt, resulting in loss of performance of PEMFC. Therefore, more corrosion resistant, electrochemically stable and lowcost supports are highly desired for PEMFCs' improved performance.Methanol oxidation reaction (MOR) is an anodic half reaction occurs at anodes of methanol fuel cells. Pt/C catalyst is also commonly used for that reaction. This thesis attempts to rationally design and synthesize various different nanostructured alternatives to carbon black for ORR and MOR. Graphene, a high conductive and stable two-dimensional carbon support, was successfully exfoliated electrochemically with little defects. Platinum (Pt) nanoparticles were deposited on graphene via double-pulse deposition technique. The catalyst was demonstrated to be highly efficient for MOR with a 920 mA/mg forward current density.Durable carbon nanotube (CNT) microspheres were synthesized through a facile and scalable ultrasonic bonding method without any binder or surfactant. The CNT microspheres with electrodeposited Pt were showcased as efficient ORR catalyst supports which showed no degradation after 12, 000 cycles (26.6 h). Furthermore, a soluble acicular calcium carbonate (aragonite, diameter 100 nm; length 800 nm) was used to created connected porosity in the microspheres to improve the mass transfer as the thickness increases. As for the ORR catalysis performance, the Pt decorated microspheres with macropores was 3.4 times higher (specific activity at 0.9V vs RHE) than non-macroporous microspheres with the identical Pt loading.Besides carbon-based supports, TiC was investigated as a potential carbon alternative due to its metallic electrical conductivity and excellent corrosion resistance. A cobalt oxide shell with high ORR activity was deposited onto TiC to improve its stability at high potential. We demonstrated that the oxide anchored Pt on TiC catalysts exhibited excellent durability (~100% catalytic activity remained at 0.1M KOH, and ~92% catalytic activity remained at 0.1M HClO4 after 16.7 h) compared to the Pt/C (~50% remained in both alkaline and acidic solutions). As assessed by transmission electron microscope (TEM), no significant Pt detachment or agglomeration was observed in oxide anchored catalysts, while heavily agglomeration has occurred to Pt/C.Hematene, two-dimensional layer of hematite (Fe2O3), has recently been exfoliated by means of liquid exfoliation. As the biodegradable metal, Fe-based materials attracts lots of attentions due to their ability to be entirely dissolved and cleared from the body. Electronics comprised of biodegradable metals can be programmed to degrade after the implantation. Here, we fabricated potentially biodegradable electrodes by using Au and hematene for glucose oxidation. It showed 9.5 mA/mgAu oxidation current density at the potential of 0.6V (vs. RHE), and high stability during the continuous cell cycling. Additionally, the prepared catalyst exhibited short response time and linear calibration range.
520 $a L'utilisation d'electrocatalyseurs pour la production efficace d'energie propre est une necessite. Parmi les nombreux processus electrocatalytiques, la reaction de reduction de l'oxygene (RRO) suscite de plus en plus d'interet, etant un des principes de base des cellules electrochimiques propres. Les piles a combustible a membrane echangeuse de protons (PCMEP) representent l'une des applications les plus fondamentales de la RRO. Elles sont considerees comme un systeme de production d'energie prometteur en raison de leur basse temperature de fonctionnement (70-90 °C), de leur source d'energie durable (hydrogene) et de leur rendement energetique elevee. La RRO est une demi-reaction cle qui se produit au niveau des cathodes du systeme avec une cinetique lente qui requiert donc la presence d'electrocatalyseurs en metal noble (e.g., platine) afin de l'accelerer pour ainsi satisfaire les exigences applicatives. Neanmoins le cout eleve et la faible durabilite des systemes commerciaux (Pt /C) representent des desavantages majeurs : la corrosion des supports de carbone entrainent une degradation de l'onereux electrocatalyseur en platine et donc une perte notable d'efficacite des PCMEP. Par consequent, des supports plus resistants a la corrosion, electrochimiquement stables et a faible cout sont fortement souhaites pour le succes commercial des PCMEP.La reaction d'oxydation du methanol (ROM) est la demi-reaction qui se produit au niveau des anodes des cellules electrochimiques a methanol. Le catalyseur Pt /C est egalement couramment utilise pour cette reaction. Cette these vise a concevoir et a elaborer diverses alternatives aux systemes commerciaux bases sur l'utilisation de supports en noir de carbone pour les reactions de reduction de l'oxygene et d'oxydation du methanol (respectivement RRO et ROM). Des feuillets de graphene, un support bidimensionnel hautement conducteur et stable, a ete exfolie avec succes par electrochimie, ne generant que peu de defauts. Des nanoparticules de platine (Pt) ont ete deposees sur ces feuillets par depot en double impulsion. Le catalyseur s'est avere tres efficace pour le MOR avec une densite de courant directe de 920 mA mg-1.Des microspheres de nanotube de carbone durables (NTC) ont ete synthetisees par une methode de liaison par ultrasons, simple et evolutive, sans liant ni surfactant. Apres electrodeposition de Pt, ces dernieres se sont averees des supports de catalyseur RRO efficaces qui ne presentaient aucune degradation apres 12 000 cycles (26,6 h). En outre, un carbonate de calcium aciculaire soluble (aragonite, diametre 100 nm; longueur 800 nm) a ete utilise pour generer une porosite connectee l'interieur de ces microspheres afin d'ameliorer le transfert de masse. La presence d'un reseau de macropores interconnectes dans les microspheres a ameliore la catalyse de la RRO d'un facteur 3,4 en comparaison avec des microspheres nanoporeuses comportant un taux similaire de Pt (activite specifique a 0,9V vs ERH).Outre les supports a base de carbone, le carbure a egalement ete considere comme un alternative viable en raison de sa conductivite electrique et de sa resistance elevee a la corrosion. Une couche d'oxyde de cobalt comportant une haute activite envers la RRO a ete deposee sur un support TiC afin d'augmenter sa stabilite a des potentiels eleves. Nous avons demontre que les catalyseurs d'oxyde de cobalt incrustes de Pt deposes sur les support TiC presentaient une excellente durabilite (≈ 100% d'activite catalytique demeurait a 0,1 M KOH et environ 92% d'activite catalytique a 0,1 M HClO4 apres 16,7 h) par rapport a au systeme (Pt / C) commercial (≈ 50% d'activite catalytique en milieu acide ou basique). Aucun detachement ou agglomeration de Pt significatif n'a ete observe par MET pour les systemes (oxyde de coblat-Pt/TiC), tandis qu'une forte agglomeration s'est produite sur les sytemes (Pt /C).Enfin, des electrodes basees sur l'exfoliation en milieu liquide de feuillets 2D en hematite (i.e. hematene, Fe2O3) ont ete elaborees. Un interet croissant est porte sur de telles electrodes a base metallique, du fait de leur capacite a etre totalement biodegradees une fois dans implantees l'organisme : en vue, la fabrication de systemes electroniques implantables a biodegradation programmee. Dans notre cas, ces electrodes totalement biodegradables composees d'hematene et d'or concues specifiquement pour la reaction d'oxydation du glucose ont demontre une haute stabilite lors du fonctionnement et une densite de courant d'oxydation de 9,5 mA / mgAu (activite specifique a 0,6V vs ERH). De plus, le catalyseur prepare presentait un temps de reponse court et une plage d'etalonnage lineaire.
590 $a School code: 0781.
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