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Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices / Bill Gannon

Swansea University Author: Bill Gannon

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DOI (Published version): 10.23889/SUthesis.57775

Abstract

A number of material coatings were investigated, specifically for 316-grade stainlesssteel electrodes, for use with alkaline water-splitting electrolysis. The aim was to enhancelongevity, particularly with respect to the highly intermittent usage that is typical of renewableenergy generation, and to...

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Published: Swansea 2021
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Dunnill, Charles W.
URI: https://cronfa.swan.ac.uk/Record/cronfa57775
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first_indexed 2021-09-06T10:49:55Z
last_indexed 2021-09-07T03:22:00Z
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spelling 2021-09-06T12:34:26.4549578 v2 57775 2021-09-06 Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices 98bbf039bdc4835b1cbee374c8acd399 Bill Gannon Bill Gannon true false 2021-09-06 CHEG A number of material coatings were investigated, specifically for 316-grade stainlesssteel electrodes, for use with alkaline water-splitting electrolysis. The aim was to enhancelongevity, particularly with respect to the highly intermittent usage that is typical of renewableenergy generation, and to increase activity. Long-term experiments were conductedover many thousands of cycles of on-off accelerated ageing at constant current density. Theeffects of ageing were analysed using chronopotentiometry, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy, energy dispersivex-ray spectroscopy, x-ray photoelectron spectroscopy and gas chromatography. It was foundthat titanium nitride did not have high activity for the hydrogen evolution reaction (HER),and underwent rapid oxidation and destruction if used as an anode. A new version ofelectrodeposited Raney nickel was developed that demonstrated improved activity, includingan overpotential for the HER at 10mAcm-2 of just 28 mV. As a bifunctional catalystit demonstrated an overpotential at 10mAcm-2 of just 319 mV, making it the second mostactive catalyst known, and certainly the simplest to deposit. This activity was traced to theincreased electrochemical surface area of the coating, which was higher as deposited, andincreased by up to a factor of three after ageing. During surface-area measurements, anapparent anomaly was discovered between results obtained for the same electrode via EISand CV. New methods of equivalent circuit fitting to transient waveforms were developed,and the anomaly was explained by time-domain simulations of the constant-phase elementrepresentation of the double-layer capacitance. A zero-gap electrolyser was constructed inorder to investigate its performance, and it was found that woven stainless-steel mesh couldoperate as a gas-separation membrane. E-Thesis Swansea alkaline electrolysis, water-splitting, electrocatalyst, titanium nitride, raney nickel 6 9 2021 2021-09-06 10.23889/SUthesis.57775 Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices © 2021 by William, J.F. Gannon is licensed under CC BY 4.0 COLLEGE NANME Chemical Engineering COLLEGE CODE CHEG Swansea University Dunnill, Charles W. Doctoral Ph.D Zienkiewicz PhD Scholarship from Swansea University 2021-09-06T12:34:26.4549578 2021-09-06T11:43:48.0940941 Faculty of Science and Engineering School of Engineering and Applied Sciences - Chemical Engineering Bill Gannon 1 57775__20747__bb41e006854a4f6f9b9f497db4bf396c.pdf wjg-thesis-main.pdf 2021-09-06T12:14:10.5995687 Output 23226865 application/pdf Version of Record true Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices © 2021 by William, J.F. Gannon is licensed under CC BY 4.0 true eng https://creativecommons.org/licenses/by/4.0/?ref=chooser-v1
title Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices
spellingShingle Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices
Bill Gannon
title_short Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices
title_full Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices
title_fullStr Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices
title_full_unstemmed Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices
title_sort Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices
author_id_str_mv 98bbf039bdc4835b1cbee374c8acd399
author_id_fullname_str_mv 98bbf039bdc4835b1cbee374c8acd399_***_Bill Gannon
author Bill Gannon
author2 Bill Gannon
format E-Thesis
publishDate 2021
institution Swansea University
doi_str_mv 10.23889/SUthesis.57775
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Chemical Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Chemical Engineering
document_store_str 1
active_str 0
description A number of material coatings were investigated, specifically for 316-grade stainlesssteel electrodes, for use with alkaline water-splitting electrolysis. The aim was to enhancelongevity, particularly with respect to the highly intermittent usage that is typical of renewableenergy generation, and to increase activity. Long-term experiments were conductedover many thousands of cycles of on-off accelerated ageing at constant current density. Theeffects of ageing were analysed using chronopotentiometry, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy, energy dispersivex-ray spectroscopy, x-ray photoelectron spectroscopy and gas chromatography. It was foundthat titanium nitride did not have high activity for the hydrogen evolution reaction (HER),and underwent rapid oxidation and destruction if used as an anode. A new version ofelectrodeposited Raney nickel was developed that demonstrated improved activity, includingan overpotential for the HER at 10mAcm-2 of just 28 mV. As a bifunctional catalystit demonstrated an overpotential at 10mAcm-2 of just 319 mV, making it the second mostactive catalyst known, and certainly the simplest to deposit. This activity was traced to theincreased electrochemical surface area of the coating, which was higher as deposited, andincreased by up to a factor of three after ageing. During surface-area measurements, anapparent anomaly was discovered between results obtained for the same electrode via EISand CV. New methods of equivalent circuit fitting to transient waveforms were developed,and the anomaly was explained by time-domain simulations of the constant-phase elementrepresentation of the double-layer capacitance. A zero-gap electrolyser was constructed inorder to investigate its performance, and it was found that woven stainless-steel mesh couldoperate as a gas-separation membrane.
published_date 2021-09-06T04:13:46Z
_version_ 1763753932751896576
score 11.012678

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