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Organic Materials for Solar Fuel Generation.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Organic Materials for Solar Fuel Generation./
作者:	Smith, Charlotte.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2019,
面頁冊數:	212 p.
附註:	Source: Dissertations Abstracts International, Volume: 83-05, Section: B.
Contained By:	Dissertations Abstracts International83-05B.
標題:	Polymers. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28781451
ISBN:	9798494453532

Organic Materials for Solar Fuel Generation.
Smith, Charlotte.

Organic Materials for Solar Fuel Generation. - Ann Arbor : ProQuest Dissertations & Theses, 2019 - 212 p.

Source: Dissertations Abstracts International, Volume: 83-05, Section: B.

Thesis (Ph.D.)--The University of Liverpool (United Kingdom), 2019.

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

In this work, organic materials have been studied for their application in photoelectrochemical water oxidation and the electrochemical reduction of CO2 in water, using porous and linear conjugated polymers and hydrogels. The use of such organic materials for solar fuel generation is highly attractive as they are cheap, relatively easy to synthesise and their structure-properties can be fine-tuned for selective gas uptake, changes in optical and physical properties such as band gap, pore size, surface area and solubility.The use of a conjugated microporous polymer containing a bipyridine (CMP-(bpy)20) unit allowed for the incorporation of a well-known CO2 molecular electrocatalyst, [Mn(bpy)(CO)3Br], in order to prevent the undesirable process of dimerisation of Mn centres prior to the formation of the catalytically active reduced species. Engineering of the electrode was explored via drop casting a suspension of CMP-(bpy)20-Mn in a polymer/acetonitrile solution, such as Nafion or PANI to aid adhesion to the electrode surface and exploit secondary functionalities such as proton and electrical conduction respectively. Although dimerisation of Mn catalyst was prevented, CO Faradaic Efficiencies and the electroactive content were low. This is likely due to only a small fraction of catalytic centres becoming electroactive due to structural distortions across the polymer backbone resulting in insulated regions, and only Mn that is in direct contact with the electrode surface is electroactive. We also explored growing CMP-(bpy)20 onto the surface of a GCE to produce thin film electrodes in an attempt to increase the planarity of CMP-(bpy)20 and diffusion through the porous structure.Two soluble linear polymers, P8s and P56, known to be good photocatalysts for hydrogen evolution were spectroscopically studied via transient absorption spectroscopy to gain insight into their photocatalytic mechanism and the role of solvents present. Due to the ease of processability and superior hydrogen evolution rate of P8s, we then went on to explore P8s as a photoanode for water oxidation purposes. XPS measurements showed P8s to be a suitable material for overall water splitting as it straddles the band gap for both hydrogen and oxygen evolution. Improved photocurrents were achieved by the fabrication of a heterojunction using TiO2 by a factor of 30 reaching photocurrents up to 20.97 µA.cm-2 . Photoactivity was further enhanced by increasing the amount of absorbed photons by using high surface area mesoporous TiO2. Transient absorption spectroelectrochemistry gave insight into the excited state dynamics of the photoanode and their lifetimes, which showed a longlived hole in the material. Utilisation of the hole was demonstrated by the addition of a hole scavenger into the electrolyte, followed by the incorporation of a co-catalyst for water oxidation.An amino acid functionalised perylene bisimide (PBI-A) hydrogel was studied in various hydrated states using UV-Visible absorption spectroscopy and neutron scattering to explore how drying affects changes in structure. Although the overall networks were similar, drying of a PBI-A hydrogel to form a xerogel resulted in an irreversible change in packing on the molecular scale between PBI-A units within a fibre. Spectroscopic studies showed a longlived charge separated state under visible light illumination unlike previous reports of dominant UV activity for this class of materials. Therefore we tested the materials as photoanodes for water oxidation and explored how the difference in water content within a gel affects photoactivity and their excited state dynamics. Utilisation of the photogenerated hole was determined from oxygen evolution experiments in the addition of an IrOx water oxidation co-catalyst.

ISBN: 9798494453532Subjects--Topical Terms:

535398
Polymers.

Organic Materials for Solar Fuel Generation.
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300 $a 212 p.
500 $a Source: Dissertations Abstracts International, Volume: 83-05, Section: B.
500 $a Advisor: Cowan, Alex;Cooper, Andy I. .
502 $a Thesis (Ph.D.)--The University of Liverpool (United Kingdom), 2019.
506 $a This item must not be sold to any third party vendors.
520 $a In this work, organic materials have been studied for their application in photoelectrochemical water oxidation and the electrochemical reduction of CO2 in water, using porous and linear conjugated polymers and hydrogels. The use of such organic materials for solar fuel generation is highly attractive as they are cheap, relatively easy to synthesise and their structure-properties can be fine-tuned for selective gas uptake, changes in optical and physical properties such as band gap, pore size, surface area and solubility.The use of a conjugated microporous polymer containing a bipyridine (CMP-(bpy)20) unit allowed for the incorporation of a well-known CO2 molecular electrocatalyst, [Mn(bpy)(CO)3Br], in order to prevent the undesirable process of dimerisation of Mn centres prior to the formation of the catalytically active reduced species. Engineering of the electrode was explored via drop casting a suspension of CMP-(bpy)20-Mn in a polymer/acetonitrile solution, such as Nafion or PANI to aid adhesion to the electrode surface and exploit secondary functionalities such as proton and electrical conduction respectively. Although dimerisation of Mn catalyst was prevented, CO Faradaic Efficiencies and the electroactive content were low. This is likely due to only a small fraction of catalytic centres becoming electroactive due to structural distortions across the polymer backbone resulting in insulated regions, and only Mn that is in direct contact with the electrode surface is electroactive. We also explored growing CMP-(bpy)20 onto the surface of a GCE to produce thin film electrodes in an attempt to increase the planarity of CMP-(bpy)20 and diffusion through the porous structure.Two soluble linear polymers, P8s and P56, known to be good photocatalysts for hydrogen evolution were spectroscopically studied via transient absorption spectroscopy to gain insight into their photocatalytic mechanism and the role of solvents present. Due to the ease of processability and superior hydrogen evolution rate of P8s, we then went on to explore P8s as a photoanode for water oxidation purposes. XPS measurements showed P8s to be a suitable material for overall water splitting as it straddles the band gap for both hydrogen and oxygen evolution. Improved photocurrents were achieved by the fabrication of a heterojunction using TiO2 by a factor of 30 reaching photocurrents up to 20.97 µA.cm-2 . Photoactivity was further enhanced by increasing the amount of absorbed photons by using high surface area mesoporous TiO2. Transient absorption spectroelectrochemistry gave insight into the excited state dynamics of the photoanode and their lifetimes, which showed a longlived hole in the material. Utilisation of the hole was demonstrated by the addition of a hole scavenger into the electrolyte, followed by the incorporation of a co-catalyst for water oxidation.An amino acid functionalised perylene bisimide (PBI-A) hydrogel was studied in various hydrated states using UV-Visible absorption spectroscopy and neutron scattering to explore how drying affects changes in structure. Although the overall networks were similar, drying of a PBI-A hydrogel to form a xerogel resulted in an irreversible change in packing on the molecular scale between PBI-A units within a fibre. Spectroscopic studies showed a longlived charge separated state under visible light illumination unlike previous reports of dominant UV activity for this class of materials. Therefore we tested the materials as photoanodes for water oxidation and explored how the difference in water content within a gel affects photoactivity and their excited state dynamics. Utilisation of the photogenerated hole was determined from oxygen evolution experiments in the addition of an IrOx water oxidation co-catalyst.
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