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Оxygen reduction on polycrystalline gold and palladium electrodes and on gold modified by palladium "islands"

dc.contributor.advisorGrgur, Branimir N.
dc.contributor.otherŠtrbac, Svetlana
dc.contributor.otherRakočević, Zlatko
dc.contributor.otherGvozdenović, Milica
dc.creatorSrejić, Irina Lj.
dc.date.accessioned2020-02-27T11:21:53Z
dc.date.available2020-02-27T11:21:53Z
dc.date.available2020-07-03T09:21:25Z
dc.date.issued2019-10-22
dc.identifier.urihttps://nardus.mpn.gov.rs/handle/123456789/12104
dc.identifier.urihttp://eteze.bg.ac.rs/application/showtheses?thesesId=7256
dc.identifier.urihttps://fedorabg.bg.ac.rs/fedora/get/o:21002/bdef:Content/download
dc.identifier.urihttp://vbs.rs/scripts/cobiss?command=DISPLAY&base=70036&RID=51888143
dc.description.abstractReakcija redukcije kiseonika je izučavana u kiseloj i baznoj sredini na dobro definisanim polikristalnim elektrodama zlata, Au(poly), paladijuma, Pd(poly), kao i na bimetalnim, Pd/Au(poly), elektrodama. Modifikovane Pd/Au(poly) elektrode su dobijene metodom spontane depozicije paladijuma na Au(poly) supstrat, kod koje se jednostavnim variranjem vremena deponovanja postižu različite pokrivenosti. Površinska morfologija radnih elektroda je ispitivana tehnikom mikroskopije atomskih sila. Istovremenim snimanjem topografskih i faznih slika je dobijen sveobuhvatan uvid u različite karakteristike radnih elektroda. Na taj način, u slučaju Pd(poly) elektrode su zapažene značajne promene na površini do kojih je došlo usled odigravanja reakcija redukcije kiseonika i vodonik-peroksida. U slučaju bimetalnih Pd/Au(poly) elektroda, mikroskopija atomskih sila je pokazala da dolazi do ostrvskog rasta depozita sa pokrivenostima ispod punog monosloja. Elektrohemijska karakterizacija elektroda je vršena u radnim rastvorima tehnikom ciklične voltametrije. Metodom rotirajuće disk elektrode (RDE) je ispitana elektrokatalitička aktivnost osnovnih Au(poly), Pd(poly) i bimetalnih Pd/Au(poly) elektroda za reakciju redukcije kiseonika. Pored toga, ispitivana je i reakcija redukcije vodonik-peroksida, koji se u zavisnosti od mehanizma reakcije redukcije kiseonika može javiti ili kao proizvod ili kao intermedijer. Analizom RDE rezultata se stekao uvid u mogući reakcioni mehanizam za redukciju kiseonika na svim radnim elektrodama. Pokazano je da se na Au(poly) elektrodi redukcija kiseonika odigrava uz izmenu 2e- u kiseloj sredini, dok se u baznoj sredini sa povećanjem potencijala mehanizam reakcije menja iz 2e- u 4e- redukciju. Redukcija kiseonika na Pd(poly) elektrodi se u obe sredine pretežno odigrava 4e- serijskim reakcionim putem u oblasti potencijala gde površina paladijuma nije ili je delimično oksidovana, dok se na površini koja je oksidovana, reakcija odigrava delimično 2e- reakcionim putem. Na modifikovanim Pd/Au(poly) elektrodama se redukcija kiseonika u obe sredine odigrava 4e- reakcionim putem. Bimetalne elektrode su pokazale poboljšanu aktivnost za redukciju kiseonika u odnosu na Au(poly) supstrat u kiseloj sredini, dok aktivnost paladijuma kao aktivnije komponente bimetalnog sistema nije premašena. U alkalnoj sredini, Pd/Au(poly) elektrode su pokazale veću aktivnost za redukciju kiseonika i od Au(poly) i od Pd(poly), čime je postignut sinergetski efekat.sr
dc.description.abstractOxygen reduction reaction (ORR) was studied on polycrystalline gold, Au(poly), polycrystalline palladium, Pd(poly) and bimetallic Pd/Au(poly) electrodes in acid and alkaline solutions. Modified Pd/Au(poly) electrodes were obtained by spontaneous deposition of palladium on the Au(poly) substrate, where simple variation of the deposition time results in different coverage. Surface morphology of working electrodes was examined by atomic force microscopy technique. Comprehensive insight into different characteristics of working electrodes has been obtained by simultaneous recording of topographic and phase images. In the case of Pd(poly) electrodes, significant changes on the surface were observed due to the occurrence of oxygen and hydrogen-peroxide reduction reactions. In the case of bimetallic Pd/Au(poly) electrodes, it was concluded that there is an island growth of the deposited Pd, whereby a submonolayer coverage is obtained. Electrochemical characterization of working electrodes was performed in acid and alkaline electrolytes using a cyclic voltammetry technique. Electrocatalytic activity of bare Au(poly), Pd(poly) and bimetallic Pd/Au(poly) electrodes for ORR was examined using the rotating disk electrode (RDE) method. In addition, since hydrogen-peroxide can appear either as a product or as an intermediate during ORR, reduction reaction hydrogen-peroxide was studied. The insight into the possible reaction mechanism for the ORR on all working electrodes was obtained by analyzing the RDE results. ORR proceeds with the exchange of 2e- on the Au(poly) electrode in acid solution, while in the alkaline solution the reaction mechanism changes from 2e- to 4e- reduction with the increase of the potential. On Pd(poly) electrode, in the potential regions where Pd surface is either oxide free or partly oxidized, ORR proceeds mainly through 4e- series pathway in both media, while in the potential region where Pd surface is oxidized, reaction occurs partly through 2e- reduction. Oxygen reduction on modified Pd/Au(poly) electrodes in both media takes place through 4e- reaction pathway. Bimetallic electrodes showed improved catalytic activity for ORR with respect to Au(poly) substrate in the acid solution, while the activity of palladium, as more active component of this bimetallic system, was not exceeded. In alkaline electrolyte a synergistic effect was achieved, since Pd/Au(poly) electrodes showed greater ORR activity with respect to both Au(poly) and Pd(poly).en
dc.formatapplication/pdf
dc.languagesr
dc.publisherУниверзитет у Београду, Технолошко-металуршки факултетsr
dc.relationinfo:eu-repo/grantAgreement/MESTD/Integrated and Interdisciplinary Research (IIR or III)/45005/RS//
dc.rightsopenAccessen
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/
dc.sourceУниверзитет у Београдуsr
dc.subjectAu(poly)sr
dc.subjectAu(poly)en
dc.subjectPd(poly)en
dc.subjectPd/Au(poly)en
dc.subjectspontaneous depositionen
dc.subjectatomic force microscopyen
dc.subjectrotating disk electrodeen
dc.subjectoxygen reduction reactionen
dc.subjectPd(poly)sr
dc.subjectPd/Au(poly)sr
dc.subjectspontana depozicijasr
dc.subjectmikroskopija atomskih silasr
dc.subjectrotirajuća disk elektrodasr
dc.subjectreakcija redukcije kiseonikasr
dc.titleRedukcija kiseonika na polikristalnim elektrodama zlata, paladijuma i zlata modifikovanog "ostrvima" paladijumasr
dc.title.alternativeОxygen reduction on polycrystalline gold and palladium electrodes and on gold modified by palladium "islands"en
dc.typedoctoralThesisen
dc.rights.licenseBY-NC-ND
dc.identifier.fulltexthttps://nardus.mpn.gov.rs/bitstream/id/17742/Disertacija.pdf
dc.identifier.fulltexthttps://nardus.mpn.gov.rs/bitstream/id/17743/IzvestajKomisije22179.pdf
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/17742/Disertacija.pdf
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/17743/IzvestajKomisije22179.pdf
dc.identifier.rcubhttps://hdl.handle.net/21.15107/rcub_nardus_12104


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