In situ observation of oscillatory redox dynamics of copper

Cao, Jing; Rinaldi, Ali; Plodinec, Milivoj; Huang, Xing; Willinger, Elena; Hammud, Adnan; Hieke, Stefan Werner; Beeg, Sebastian; Gregoratti, Luca; Colbea, Claudiu; Schlögl, Robert; Antonietti, Markus; Greiner, Mark; Willinger, Marc Georg

doi:10.1038/s41467-020-17346-7

Cited by 36 publications

(34 citation statements)

References 67 publications

(100 reference statements)

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“…Therefore, the reconstruction of the copper electrodes is ruled by the incorporation of oxygen in the copper lattice as well as by the oxidation temperature indicating that the morphology changes are dominated by oxidation/reduction processes. 37 The changes induced in the morphology of the electrodes after the electrocatalytic reduction of CO 2 were also investigated. Figure 2 B2,C2 shows that the electrodes oxidized at 25 and 150 °C undergo roughness changes during the reaction.…”

Section: Results and Discussionmentioning

confidence: 99%

On the Activity/Selectivity and Phase Stability of Thermally Grown Copper Oxides during the Electrocatalytic Reduction of CO₂

et al. 2020

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Revealing the active nature of oxide-derived copper is of key importance to understand its remarkable catalytic performance during the cathodic CO 2 reduction reaction (CO 2 RR) to produce valuable hydrocarbons. Using advanced spectroscopy, electron microscopy, and electrochemically active surface area characterization techniques, the electronic structure and the changes in the morphology/roughness of thermally oxidized copper thin films were revealed during CO 2 RR. For this purpose, we developed an in situ cell for X-ray spectroscopy that could be operated accurately in the presence of gases or liquids to clarify the role of the initial thermal oxide phase and its active phase during the electrocatalytic reduction of CO 2 . It was found that the Cu(I) species formed during the thermal treatment are readily reduced to Cu 0 during the CO 2 RR, whereas Cu(II) species are hardly reduced. In addition, Cu(II) oxide electrode dissolution was found to yield a porous/void structure, where the lack of electrical connection between isolated islands prohibits the CO 2 RR. Therefore, the active/stable phase for CO 2 RR is metallic copper, independent of its initial phase, with a significant change in its morphology upon its reduction yielding the formation of a rougher surface with a higher number of underco-ordinated sites. Thus, the initial thermal oxidation of copper in air controls the reaction activity/selectivity because of the changes induced in the electrode surface morphology/roughness and the presence of more undercoordinated sites during the CO 2 RR.

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Section: Results and Discussionmentioning

confidence: 99%

On the Activity/Selectivity and Phase Stability of Thermally Grown Copper Oxides during the Electrocatalytic Reduction of CO₂

et al. 2020

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“…The derivation of the complete chemical mechanism of a particular catalyst cannot be attained without a profound understanding of the dynamics of the catalyst material, irrespective of whether e.g., an automotive three-way catalyst or a catalyst for power-to-X technologies 3 is considered. The fluctuations can be produced by external stimuli, but also by changes being induced by the action of the catalyst itself 4,5 .…”

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Stroboscopic operando spectroscopy of the dynamics in heterogeneous catalysis by event-averaging

et al. 2021

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Heterogeneous catalyst surfaces are dynamic entities that respond rapidly to changes in their local gas environment, and the dynamics of the response is a decisive factor for the catalysts’ action and activity. Few probes are able to map catalyst structure and local gas environment simultaneously under reaction conditions at the timescales of the dynamic changes. Here we use the CO oxidation reaction and a Pd(100) model catalyst to demonstrate how such studies can be performed by time-resolved ambient pressure photoelectron spectroscopy. Central elements of the method are cyclic gas pulsing and software-based event-averaging by image recognition of spectral features. A key finding is that at 3.2 mbar total pressure a metallic, predominantly CO-covered metallic surface turns highly active for a few seconds once the O2:CO ratio becomes high enough to lift the CO poisoning effect before mass transport limitations triggers formation of a √5 oxide.

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“…This description can be used for self-organised patterns on catalyst surfaces or self-sustaining waves which have been observed under operando conditions. 17,18 A combination of site heterogeneity, induced heterogeneity, and periodicity in each patch can be obtained for very complex cases, especially in redox catalysis. Consequently, due to the various forms of dynamics listed above, the conventional standard model of catalysis leading to microkinetic models is insufficient to capture the whole range of complexities that is required to bridge surface models to models for technical catalysts.…”

Section: Framework For Coupling Surface Models With Reactor Models An...mentioning

confidence: 99%

Advanced Kinetic Characterization

Omojola¹

2022

Preprint

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Microkinetic analysis that assumes the steady-state approximation are ubiquitous in the modelling and simulations of redox and non-redox reactions. Operando studies such as photoemission electron microscopic investigations have, however, provided evidence for (a)periodic surface concentration profiles and adspecie mobility. Consequently, the ubiquitous steady-state approximation used in nearly all (micro)-kinetic models may not be universally applicable. Furthermore, on unsupported and unpromoted catalyst surfaces, variations in the nature, quantity, and mobility of active sites are observed leading to various forms of site heterogeneity, induced heterogeneity, or both, as well as (a)periodic heterogeneity in the form of oscillatory waves and self-organised patterns. The relationship between surface-site distribution and the ensuing homogeneity and/or heterogeneity and product distribution and the resulting modelling tools used for analysis have not been explored comprehensively. Consequently, we provide a framework for cataloguing catalysts for advanced kinetic characterisation and modelling. The catalogue has two functions: (1) it relates surface models with reactor models, and (2) for any specific reaction, it shows (visually) the dynamicity of adspecie formation and evolution on the catalyst surface. Indeed, this second advantage has been exemplified by archived studies of carbon monoxide oxidation over Pd(111) catalysts. Using the homotattic patch model that leads to the adsorption integral equation, we catalogue catalysts according to evolving active sites on catalyst surfaces with varied homogeneity. We observe that the conventional microkinetic models are only accurate for a very small subset of chemical reactions where the standard model of catalysis applies. However, for many redox catalytic transformations, these models lose their applicability with respect to the dynamics of the active site, catalyst surface, and reaction. As a substitute, we present microdynamic models which not only account for every elementary reaction step but incorporate a multi-scale approach within kinetic models allowing for changing catalyst states, charge transport, as well as active site, catalyst surface, reaction, and reactor dynamics.

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In situ observation of oscillatory redox dynamics of copper

Cited by 36 publications

References 67 publications

On the Activity/Selectivity and Phase Stability of Thermally Grown Copper Oxides during the Electrocatalytic Reduction of CO₂

On the Activity/Selectivity and Phase Stability of Thermally Grown Copper Oxides during the Electrocatalytic Reduction of CO₂

Stroboscopic operando spectroscopy of the dynamics in heterogeneous catalysis by event-averaging

Advanced Kinetic Characterization

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In situ observation of oscillatory redox dynamics of copper

Cited by 36 publications

References 67 publications

On the Activity/Selectivity and Phase Stability of Thermally Grown Copper Oxides during the Electrocatalytic Reduction of CO2

On the Activity/Selectivity and Phase Stability of Thermally Grown Copper Oxides during the Electrocatalytic Reduction of CO2

Stroboscopic operando spectroscopy of the dynamics in heterogeneous catalysis by event-averaging

Advanced Kinetic Characterization

Contact Info

Product

Resources

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On the Activity/Selectivity and Phase Stability of Thermally Grown Copper Oxides during the Electrocatalytic Reduction of CO₂

On the Activity/Selectivity and Phase Stability of Thermally Grown Copper Oxides during the Electrocatalytic Reduction of CO₂