气候变化领域集成服务门户(CCPortal): Operando X-ray characterization of high surface area iridium oxides to decouple their activity losses for the oxygen evolution reaction

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DOI	10.1039/c9ee01018a
	Operando X-ray characterization of high surface area iridium oxides to decouple their activity losses for the oxygen evolution reaction
	Povia M.; Abbott D.F.; Herranz J.; Heinritz A.; Lebedev D.; Kim B.-J.; Fabbri E.; Patru A.; Kohlbrecher J.; Schäublin R.; Nachtegaal M.; Copéret C.; Schmidt T.J.
发表日期	2019
ISSN	17545692
起始页码	3038
结束页码	3052
卷号	12 期号:10
英文摘要	IrO2 is the state-of-art O2-evolution reaction (OER) electrocatalyst implemented in proton exchange membrane electrolyzers, but in the near future iridium's ultra-low availability could threaten the successful development of this technology. To minimize this dependency, Ir-oxides with enhanced mass-specific surface areas and OER-activities are progressively being developed, but often suffer from a poorly understood deactivation under operating conditions. To understand this activity loss, in this study we used a modified Adams' fusion method to produce an Ir-oxide with a surface area of ≈350 m2 g-1 that consists of nano-disks with their surface partially covered by a layer of Ir(OOH). In order to investigate the effect of this surface oxidation state on the catalyst's reactivity and stability, a fraction of this as-synthetized sample was submitted to a second heat-treatment in air to further oxidize its surface (i.e., yielding IrO2 with ≈250 m2 g-1). While electrochemical characterization through rotating disk electrode voltammetry unveiled that the as-synthesized catalyst features a ≈2-fold larger surface-specific OER-activity than its heat-treated derivative, it also undergoes a greater loss of such activity in the course of an accelerated stress test (AST) that mimics electrolyzer startup/shutdown (≈45 vs. ≈30% OER-current decrease for the as-synthetized sample vs. its heat-treated derivative, respectively). Since ex situ analyses (e.g., through X-ray photoelectron spectroscopy) were not sufficient to explain this difference in stability, the operando changes in the samples' morphology and chemical composition were assessed using a recently developed apparatus that combines small angle X-ray scattering (SAXS) and X-ray absorption spectroscopy (XAS). While the XAS measurements demonstrated the compositional stability of both catalysts (i.e., oxidation state and local geometric structure), SAXS showed that the as-synthetized catalyst is made of two-dimensionally agglomerated disks that become thinner and wider in the course of the AST, whereas the heat-treated sample is composed of morphologically stable, sintered particles in the form of rough and porous agglomerates. Considering the complementary information provided by these operando and ex situ techniques, it was then possible to quantify the contributions of Ir-dissolution, surface area loss and changes in the surface oxidation state to the destabilization of both catalysts. © 2019 The Royal Society of Chemistry.
英文关键词	Agglomeration; Chemical analysis; Chemical stability; Curricula; Electrocatalysts; Electrolytic cells; Morphology; Oxidation; Oxygen; Rotating disks; X ray absorption spectroscopy; X ray photoelectron spectroscopy; X ray scattering; Chemical compositions; Compositional stability; Electrochemical characterizations; Local geometric structures; Oxygen evolution reaction; Proton exchange membrane electrolyzers; Rotating disk electrode voltammetry; X-ray characterization; Iridium compounds; catalyst; chemical composition; chemical reaction; detection method; electrode; inorganic compound; oxidation; oxygen
语种	英语
来源期刊	Energy & Environmental Science
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/189800
作者单位	Electrochemistry Laboratory, Paul Scherrer Institut, Villigen, 5232, Switzerland; Department of Chemistry and Applied Biosciences, ETH Zurich Vladimir, Prelog Weg. 1-5, Zurich, CH-8093, Switzerland; Laboratory for Neutron Scattering, Paul Scherrer Institute, Villigen, 5232, Switzerland; Scientific Center for Optical and Electron Microscopy, ETH Zurich, Auguste-Piccard-Hof 1, Zurich, 8093, Switzerland; Paul Scherrer Institut, Villigen, 5232, Switzerland; Laboratory of Physical Chemistry, ETH Zurich, Zurich, 8093, Switzerland
推荐引用方式 GB/T 7714	Povia M.,Abbott D.F.,Herranz J.,et al. Operando X-ray characterization of high surface area iridium oxides to decouple their activity losses for the oxygen evolution reaction[J],2019,12(10).
APA	Povia M..,Abbott D.F..,Herranz J..,Heinritz A..,Lebedev D..,...&Schmidt T.J..(2019).Operando X-ray characterization of high surface area iridium oxides to decouple their activity losses for the oxygen evolution reaction.Energy & Environmental Science,12(10).
MLA	Povia M.,et al."Operando X-ray characterization of high surface area iridium oxides to decouple their activity losses for the oxygen evolution reaction".Energy & Environmental Science 12.10(2019).