Simulation of electrochemical processes during oxygen evolution on Pb-MnO2 composite electrodes

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Forsén, Olof fi
dc.contributor.author Schmachtel, Sönke
dc.contributor.author Murtomäki, Lasse fi
dc.contributor.author Aromaa, Jari fi
dc.contributor.author Lundström, Mari fi
dc.contributor.author Barker, Michael H. fi
dc.date.accessioned 2019-10-22T09:01:43Z
dc.date.available 2019-10-22T09:01:43Z
dc.date.issued 2017
dc.identifier.citation Schmachtel, Sönke & Murtomäki, Lasse & Aromaa, Jari & Lundström, Mari & Barker, Michael H. 2017. Simulation of electrochemical processes during oxygen evolution on Pb-MnO2 composite electrodes. Electrochimica Acta. Volume 245. 28+6. en
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/40758
dc.description.abstract The geometric properties of Pb-MnO2 composite electrodes are studied, and a general formula ispresented for the length of the triple phase boundary (TPB) on two dimensional (2D) compositeelectrodes using sphere packing and cutting simulations. The difference in the geometrical properties of2D (or compact) and 3D (or porous) electrodes is discussed. It is found that the length of the TPB is theonly reasonable property of a 2D electrode that follows a 1/r particle radius relationship. Subsequently,sphere packing cuts are used to derive a statistical electrode surface that is the basis for the earlierproposed simulations of different electrochemical mechanisms. It is shown that two of the proposedmechanisms (conductivity and a two-step-two-material kinetic mechanism) can explain the currentincrease at Pb-MnO2 anodes compared to standard lead anodes.The results show that although MnO2 has low conductivity, when combined with Pb as the metal matrix,the behaviour of the composite is not purely ohmic but is also affected by activation overpotentials,increasing the current density close to the TPB. Current density is inversely proportional to the radius ofthe catalyst particles, matching with earlier experimental results. Contrary to earlier SECM experiments,mass transport of sulphuric acid is not likely to have any influence, as confirmed with simulations.A hypothetical two-step-two-material mechanism with intermediate H2O2 that reacts on both the Pbmatrix and MnO2 catalyst is studied. It was found that assuming quasi-reversible generation of H2O2followed by its chemical decomposition on MnO2, results are obtained that agree with the experiments.If the quasi-reversible formation of H2O2 occurs near the peroxide decomposition catalyst, currentincreases, leading to an active TPB and to the current density that scales with 1/r. It is furtheremphasised that both the Pb matrix and MnO2 catalyst are necessary and their optimum ratio dependson the used current density. Yet, additional experimental evidence is needed to support the postulatedmechanism. en
dc.format.extent 28+6
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher Elsevier en
dc.relation.ispartofseries Electrochimica Acta fi
dc.relation.ispartofseries Volume 245 fi
dc.rights © 2017 Elsevier. This is the post print version of the following article: Schmachtel, Sönke & Murtomäki, Lasse & Aromaa, Jari & Lundström, Mari & Barker, Michael H. 2017. Simulation of electrochemical processes during oxygen evolution on Pb-MnO2 composite electrodes. Electrochimica Acta. Volume 245. 28+6, which has been published in final form at http://www.sciencedirect.com/science/article/pii/S001346861730912X. This post-print is published with permission from Elsevier under CC BY-NC-ND 4.0 license (http://creativecommons.org/licenses/by-nc-nd/4.0/) en
dc.subject.other Chemistry en
dc.subject.other Metallurgy en
dc.subject.other Technology en
dc.title Simulation of electrochemical processes during oxygen evolution on Pb-MnO2 composite electrodes en
dc.type A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä fi
dc.description.version Peer reviewed en
dc.rights.holder Elsevier
dc.contributor.school Kemian tekniikan korkeakoulu fi
dc.contributor.school School of Chemical Technology en
dc.contributor.department Kemian laitos fi
dc.contributor.department Department of Chemistry en
dc.subject.keyword Oxygen evolution on composite electrode en
dc.subject.keyword metal electrowinning en
dc.subject.keyword triple phase boundary length en
dc.subject.keyword two-step two-material mechanism en
dc.subject.keyword diffusion domain approach en
dc.identifier.urn URN:NBN:fi:aalto-201705103815
dc.type.dcmitype text en
dc.contributor.lab Laboratory of Physical Chemistry and Electrochemistry en
dc.type.version Post print en


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