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Interface analysis and development of BiVO4 and CuFeO2 heterostructures for photochemical water splitting

Hermans, Yannick (2019):
Interface analysis and development of BiVO4 and CuFeO2 heterostructures for photochemical water splitting.
Darmstadt, Technische Universität,
[Ph.D. Thesis]

Abstract

Solar photo(electro)chemical (PEC) water splitting is regarded as a promising ways of renewable hydrogen production. Especially, type 2 PEC systems, in which the necessary energy needed to split water can be supplied by two complimentary photoabsorbers, have the potential to economically compete with steam methane reforming, the conventional hydrogen production method. In this work, BiVO4 and CuFeO2 were chosen to perform the water oxidation and water reduction reaction, respectively. However, according to literature additional contact materials are required to achieve a reasonable water splitting performance. The exact benefits of these contact materials have not yet been completely elucidated. Therefore, we opted in this work to investigate the junction properties of certain BiVO4 and CuFeO2 based heterostructures through so called interface experiments, whereby a certain contact material was stepwise sputtered onto a BiVO4 or CuFeO2 substrate, performing photoelectron spectroscopy measurements in between each deposition step. In this way we could interpret the band alignment between the substrate and the contact material, as well as determine the Fermi level tunability for the studied photoabsorbers. In parallel, new anisotropic CuFeO2 and BiVO4 based heterostructured powders were created through photodeposition. In particular, silver, platinum, cobalt(oxy)(hydr)oxide and nickel(oxy)(hydr)oxide were successfully deposited onto anisotropically shaped BiVO4 and CuFeO2 powders. These powders were tested as well for their performance in photochemical water splitting.

Item Type: Ph.D. Thesis
Erschienen: 2019
Creators: Hermans, Yannick
Title: Interface analysis and development of BiVO4 and CuFeO2 heterostructures for photochemical water splitting
Language: English
Abstract:

Solar photo(electro)chemical (PEC) water splitting is regarded as a promising ways of renewable hydrogen production. Especially, type 2 PEC systems, in which the necessary energy needed to split water can be supplied by two complimentary photoabsorbers, have the potential to economically compete with steam methane reforming, the conventional hydrogen production method. In this work, BiVO4 and CuFeO2 were chosen to perform the water oxidation and water reduction reaction, respectively. However, according to literature additional contact materials are required to achieve a reasonable water splitting performance. The exact benefits of these contact materials have not yet been completely elucidated. Therefore, we opted in this work to investigate the junction properties of certain BiVO4 and CuFeO2 based heterostructures through so called interface experiments, whereby a certain contact material was stepwise sputtered onto a BiVO4 or CuFeO2 substrate, performing photoelectron spectroscopy measurements in between each deposition step. In this way we could interpret the band alignment between the substrate and the contact material, as well as determine the Fermi level tunability for the studied photoabsorbers. In parallel, new anisotropic CuFeO2 and BiVO4 based heterostructured powders were created through photodeposition. In particular, silver, platinum, cobalt(oxy)(hydr)oxide and nickel(oxy)(hydr)oxide were successfully deposited onto anisotropically shaped BiVO4 and CuFeO2 powders. These powders were tested as well for their performance in photochemical water splitting.

Place of Publication: Darmstadt
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Surface Science
Date Deposited: 16 Jun 2019 19:55
Official URL: https://tuprints.ulb.tu-darmstadt.de/8700
URN: urn:nbn:de:tuda-tuprints-87001
Referees: Jaegermann, Prof. Dr. Wolfram ; Toupance, Prof. Dr. Thierry
Refereed / Verteidigung / mdl. Prüfung: 6 May 2019
Alternative Abstract:
Alternative abstract Language

Die photo(elektro)chemische (PEC) Wasserspaltung ist ein vielversprechender Weg zur Erzeugung von Wasserstoff aus erneuerbaren Energiequellen. Insbesondere PEC-Systeme vom Typ 2, bei denen die erforderliche Energie zum spalten von Wasser von zwei komplementaren Photoabsorbern bereitgestellt werden kann, haben das Potenzial wirtschaftlich zu konkurrieren mit der Dampfreformierung von Methan, dem herkömmlichen Verfahren zur Wasserstofferstellung. In dieser Arbeit wurden BiVO4 und CuFeO2 ausgewählt, um die Wasseroxidation beziehungsweise Wasserreduktion durchzuführen. Laut Literatur sind jedoch zusätzliche Kontaktmaterialien erforderlich um eine angemessene Wasserspaltleistung zu erreichen. Die genauen Vorteile dieser Kontaktmaterialien sind noch nicht vollstandig geklärt. Deshalb wurde sich in dieser Arbeit da zu entschieden, die Heteroübergangseigenschaften bestimmter BiVO4-und CuFeO2-basierter Heterostrukturen durch sogenannte Grenzflächenexperimente zu untersuchen. Innerhalb dieser Grenzflächenexperiment wurde ein bestimmtes Kontaktmaterial schrittweise auf ein BiVO4-oder CuFeO2-Substrat gesputtert und photoelektronenspektroskopische Messungen zwischen jedem Abscheidungsschritt durchgeführt. Auf diese Weise könnte die Bandanpassung zwischen dem Substrat und dem Kontaktmaterial sowie die maximal mögliche Variierung des Fermi-Niveaus fur die untersuchten Photoabsorbern bestimmt werden. Ein weiterer Teil dieser Arbeit umfasst die Herstellung von neuen anisotropen heterostrukturierten CuFeO2-und BiVO4-Pulvern durch Photodeposition. Insbesondere wurde Silber, Platin, Cobalt(oxy)(hydr)oxid und Nickel(oxy)(hydr)oxid auf anisotrop geformten BiVO4-und CuFeO2-Pulvern abgeschieden. Diese Pulvern wurden auf ihre Leistung bei der photochemischen Wasserspaltung getestet.

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