Mierwaldt, Daniel

[["dc.bibliographiccitation.firstpage","3378"],["dc.bibliographiccitation.issue","16"],["dc.bibliographiccitation.journal","Advanced Functional Materials"],["dc.bibliographiccitation.lastpage","3388"],["dc.bibliographiccitation.volume","22"],["dc.contributor.author","Raabe, Stephanie"],["dc.contributor.author","Mierwaldt, Daniel"],["dc.contributor.author","Ciston, Jim"],["dc.contributor.author","Uijttewaal, Matthe"],["dc.contributor.author","Stein, Helge"],["dc.contributor.author","Hoffmann, Joerg"],["dc.contributor.author","Zhu, Y."],["dc.contributor.author","Bloechl, Peter E."],["dc.contributor.author","Jooss, Christian"],["dc.date.accessioned","2018-11-07T09:07:08Z"],["dc.date.available","2018-11-07T09:07:08Z"],["dc.date.issued","2012"],["dc.description.abstract","Fundamental studies of catalysts based on manganese oxide compounds are of high interest since they offer the opportunity to study the role of variable valence state in the active state during O2 evolution from H2O. This paper presents a study of doping dependent O2 evolution electrocatalysis of Pr-doped CaMnO3 via in situ environmental transmission electron microscopy (ETEM) combined with ex situ cyclic voltammetry studies. ETEM studies of heterogeneous catalysis are a challenge, since the reactions in the H2O vapor phase cannot directly be observed. It is shown that the oxidation of silane by free oxygen to solid SiO2-x can be used to monitor catalytic oxygen evolution. Electron energy loss spectroscopy (EELS) as well as the in situ X-ray absorption study of near edge structures (XANES) in H2O vapor reveals that the Mn valence is decreased in the active state. Careful TEM analysis of samples measured by ex situ cyclic voltammetry and an in situ bias-controlled ETEM study allows us to distinguish between self-formation during oxygen evolution and corrosion at the Pr1-xCaxMnO3-H2O interface. Including density functional theory (DFT) calculations, trends in O2 evolution activity and defect chemistry in the active state can be correclated to doping induced changes of the electronic band structure in A-site doped manganites."],["dc.identifier.doi","10.1002/adfm.201103173"],["dc.identifier.isi","000307566200003"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/25721"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1616-3028"],["dc.relation.issn","1616-301X"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","In Situ Electrochemical Electron Microscopy Study of Oxygen Evolution Activity of Doped Manganite Perovskites"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","5301"],["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","The Journal of Physical Chemistry C"],["dc.bibliographiccitation.lastpage","5310"],["dc.bibliographiccitation.volume","119"],["dc.contributor.author","Mildner, Stephanie"],["dc.contributor.author","Beleggia, Marco"],["dc.contributor.author","Mierwaldt, Daniel"],["dc.contributor.author","Hansen, Thomas W."],["dc.contributor.author","Wagner, Jakob B."],["dc.contributor.author","Yazdi, Sadegh"],["dc.contributor.author","Kasama, Takeshi"],["dc.contributor.author","Ciston, Jim"],["dc.contributor.author","Zhu, Y."],["dc.contributor.author","Jooß, Christian"],["dc.date.accessioned","2018-11-07T09:59:43Z"],["dc.date.available","2018-11-07T09:59:43Z"],["dc.date.issued","2015"],["dc.description.abstract","Environmental transmission electron microscopy (ETEVI) studies offer great potential for gathering atomic scale information on the electronic state of electrodes in contact with reactants. It also poses big challenges due to the impact of the high energy electron beam. In this article, we present an ETEM study of a Pr0.64Ca0.36MnO3 (PCMO) thin filth electrocatalySt for water splitting and Oxygen evolution in contact with water vapor: We show by means of off-axis electron holography and electrostatic modeling that the electron beam gives rise to a positive electric sample potential due to secondary electron emission. The value of the electric potential depends on the primary electron flux, the sample's electric Conductivity and grounding, and gas properties. We present evidence that two observed electrochemical reactions are driven by a beam induced electrostatic potential of the order of a volt. The first reaction is an anodic oxidation of oxygen depleted amorphous PCMO which results in recrystallization of the oxide. The Second reaction is oxygen evolution which can be detected by the oxidation of a silane additive and formation of SiO2-gamma at catalytically active surfaces. The quantification of beam induced potentials is an important step for future controlled electrochemical experiments in an ETEM."],["dc.description.sponsorship","DFG [SFB 1073]"],["dc.identifier.doi","10.1021/jp511628c"],["dc.identifier.isi","000351189100006"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/37654"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation","SFB 1073: Kontrolle von Energiewandlung auf atomaren Skalen"],["dc.relation","SFB 1073 | Topical Area C | C02 In situ hochauflösende Untersuchung des aktiven Zustands bei der photo- und elektrochemischen Wasserspaltung"],["dc.relation.issn","1932-7447"],["dc.relation.orgunit","Institut für Materialphysik"],["dc.title","Environmental TEM Study of Electron Beam Induced Electrochemistry of Pr0.64Ca0.36MnO3 Catalysts for Oxygen Evolution"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]