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dc.contributor.advisorSüzer, Şefik
dc.contributor.authorCamcı, Merve
dc.date.accessioned2017-01-02T08:31:50Z
dc.date.available2017-01-02T08:31:50Z
dc.date.copyright2016-12
dc.date.issued2015-12
dc.date.submitted2016-12-27
dc.identifier.urihttp://hdl.handle.net/11693/32599
dc.descriptionCataloged from PDF version of article.en_US
dc.descriptionThesis (Ph.D.): Bilkent University, Department of Chemistry, İhsan Doğramacı Bilkent University, 2016.en_US
dc.descriptionIncludes bibliographical references (leaves 97-111).en_US
dc.description.abstractAttention towards electrochemical energy storage devices assembled with innovative solvent-free electrolytes ‘ionic liquids’ (ILs) has been progressively rising over the last two decades. In order to design a particular electrochemical device it becomes crucial to understand the structure of interfacial region and the electrical response of ILs. Accordingly, this thesis focuses on Xray Photoelectron Spectroscopic (XPS) investigations of electrochemical devices containing ILs, that is compatible with ultra high vacuum condition needed for XPS. Towards better understanding the fundamental aspects of certain electrochemical issues, electrochemical devices consisting of two metalelectrodes, which contains N,N – Diethyl -N- methyl -N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide, (DEME-TFSI) IL-electrolyte between them, have been investigated by XPS under external electrical stimuli control, as a novel analytical tool for elucidating; (i) charging/ discharging phenomena, (ii) electrical double layer (EDL) formation and (iii) electrochemical reaction products. In the first part, a co-planar electrochemical device, with two gold electrodes on porous polyethylene membrane (PEM) plus DEME-TFSI impregnated between the electrodes, has been studied using external DC bias, for recording the position dependent electrical potential variations. In addition, AC bias is used to harvest temporal behavior. For the AC bias a square wave excitation is used, for which two frequencies are adopted corresponding to slow (10 mHz) and fast (1 kHz) time scales, for probing the response of the system at infinite- and zero-time onset, respectively. In all cases XP spectra have been recorded at different lateral positions. As a result of these DC and AC applications a new understanding has surfaced. Accordingly, although at the metal-electrolyte interface the EDL formation is limited to lateral dimensions at the nanometer scale, its visualization through the analysis of the XPS-probed voltage transients can be extended to very large distances from the interface, in the millimeters scale. These responses have also been modeled using a simple equivalent circuit with two oppositely polarized electrodes and an ionic conducting medium in between. In the second part, re-arrangement of the DEME-TFSI’s ionic constituents at the Au electrode/IL-electrolyte interface has been monitored by the dynamic-XPS approach under application of electrical pulses in the form of a slow (1 mHz) triangular wave with an amplitude of 5V, while recording the intensity fluctuations of the two N1s peaks corresponding to the anionic and the cationic fragments. In the last part, the externally bias XPS analysis has been used for insitu and in-vacuo monitoring of anodically triggered electrochemical preparation and characterization of Au NPs in both a co-planar and also in a wire-plane electrode electrochemical geometries. The small sized Au NPs’ formation within the DEME-TFSI medium has been confirmed by the characteristic peak around 470 nm in the Visible spectrum and with the spherical and well-dispersed (~4 nm) particles in TEM images.en_US
dc.description.statementofresponsibilityby Merve Camcı.en_US
dc.format.extentxxiii, 111 leaves : charts (some color).en_US
dc.language.isoEnglishen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectX-ray Photoelectron Spectroscopyen_US
dc.subjectIonic liquidsen_US
dc.subjectElectrical double layeren_US
dc.subjectGold nanoparticlesen_US
dc.subjectElectrochemical reductionen_US
dc.subjectIn-situ monitoring of electrochemical reactionsen_US
dc.titleInvestigation of electronic properties of ionic liquid electrochemical devices by X-ray photoelectron spectroscopyen_US
dc.title.alternativeİyonik sıvılı elektrokimyasal aygıtların elektronik özelliklerinin X-ışını fotoelektron spektroskopisiyle incelenmesien_US
dc.typeThesisen_US
dc.departmentDepartment of Chemistryen_US
dc.publisherBilkent Universityen_US
dc.description.degreePh.D.en_US
dc.identifier.itemidB154949
dc.embargo.release2019-12-27


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