dc.contributor.author
Pasquini, Chiara
dc.date.accessioned
2022-07-05T12:53:22Z
dc.date.available
2022-07-05T12:53:22Z
dc.identifier.uri
https://refubium.fu-berlin.de/handle/fub188/35419
dc.identifier.uri
http://dx.doi.org/10.17169/refubium-35134
dc.description.abstract
Hydrogen produced from water via electrolysis is the most promising carbon-free fuel at our disposal, it is considered one of the pillars for the decarbonization of our society. One of the bottlenecks for a wider application of this technology is the efficiency of the water oxidation reaction, thus, a lot of effort has been directed to the investigation of catalysts and reaction mechanisms. The amorphous Co oxide catalyst (CoCat) is particularly active at neutral pH for the water oxidation reaction. In this thesis, the reaction mechanism for CoCat is studied by simultaneous coupling of electrochemistry with spectroscopic techniques. Operando X-ray absorption spectroscopy is adapted and employed to obtain time-resolved information on oxidation state changes and detailed insights into the reaction mechanism. Operando Raman spectra are collected at various applied potentials and show spectral changes, which can be assigned to two distinct Co oxidation reactions, establishing Raman spectroscopy as a novel tool to study metal oxidation states. Furthermore, Raman spectroscopy reveals the presence of local acidification at the catalyst surface due to proton transfer limitations, which strongly affects catalyst performances. The reaction mechanism differs in alkaline electrolytes, where the catalytic efficiency is higher. The differences between the two pH regimes are investigated to unravel the key factors for catalyst efficiency.
en
dc.format.extent
206 Seiten
dc.rights.uri
http://www.fu-berlin.de/sites/refubium/rechtliches/Nutzungsbedingungen
dc.subject
electrolysis
en
dc.subject
Cobalt oxide
en
dc.subject
oxidation state
en
dc.subject
isotope effect
en
dc.subject
time resolved operando spectroscopy
en
dc.subject
X-ray absorption
en
dc.subject.ddc
500 Natural sciences and mathematics::530 Physics::537 Electricity and electronics
dc.title
The mechanism of the water oxidation reaction catalyzed by an amorphous Co-based catalyst is revealed using operando Raman and time-resolved X-ray absorption spectroscopy
dc.contributor.gender
female
dc.contributor.firstReferee
Dau, Holger
dc.contributor.furtherReferee
Hildebrandt, Peter
dc.date.accepted
2022-05-24
dc.identifier.urn
urn:nbn:de:kobv:188-refubium-35419-4
refubium.affiliation
Physik
dcterms.accessRights.dnb
free
dcterms.accessRights.openaire
open access
dcterms.accessRights.proquest
accept