Linking the evolution of catalytic properties and structural changes in copper–zinc nanocatalysts using <i>operando</i> EXAFS and neural-networks

Timoshenko, Janis; Jeon, Hyo Sang; Sinev, Ilya; Haase, Felix T.; Herzog, Antonia; Cuenya, Beatriz Roldán

doi:10.1039/d0sc00382d

Cited by 66 publications

(96 citation statements)

References 73 publications

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“…For example, Figure 1 a shows an absorption edge at ∼9.0 keV due to the absorption of X-ray photons by K-shell (1s) electrons of Cu in an oxidized Cu nanoparticle (NP). 25 In this case, the X-ray photons absorbed excite the core electrons of Cu to available unoccupied states in the valence band, resulting in the absorption edge, which then is referred to as Cu K-edge. The position of the absorption edge E 0 is element-specific, with the corresponding energies scaling approximately as Z 2 .…”

Section: Xas: Physical Principlesmentioning

confidence: 99%

“… (a) Cu K-edge XAS data for an as-prepared Cu nanocatalyst used for CO2RR (from ref ( 25 )). Schematics of the photoelectron scattering process, and pre-edge at the Cu K-edge are shown in the insets.…”

Section: Xas: Physical Principlesmentioning

confidence: 99%

“…The vertical dashed lines in panels c and d show the R -value corresponding to an average nearest neighbor Cu–O distance. See ref ( 25 ) for RMC details.…”

Section: Xas: Physical Principlesmentioning

confidence: 99%

“…In this case, the environment around the absorbing Cu 2+ species is similar to that in CuO, featuring a strongly distorted CuO 6 octahedron with axial Cu–O bonds being ∼0.8 Å longer than 4 in-plane Cu–O bonds (see the inset in Figure 1 a). 25 The resolution of the XANES features strongly depends on the absorption edge energy and for heavy elements is reduced significantly due to the high energy of the excitation and the short lifetime of the core-hole created. Improved resolution of the XANES features can be achieved in the so-called high energy resolution fluorescence detected (HERFD) mode, where instead of measuring transmission or fluorescence due to filling-in the created core hole, the fluorescence associated with a state with a longer lifetime is monitored.…”

Section: Xas: Physical Principlesmentioning

confidence: 99%

“…As an example, Figure 1 b shows Cu K-edge EXAFS spectra for oxidized Cu NPs. 25 The choice of background fitting procedure and the E 0 value selected can affect the appearance of the EXAFS features significantly, especially at low k -values, and therefore, it should be carried out systematically for all spectra in the analyzed series.…”

Section: Xas: Physical Principlesmentioning

confidence: 99%

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In Situ/Operando Electrocatalyst Characterization by X-ray Absorption Spectroscopy

2020

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During the last decades, X-ray absorption spectroscopy (XAS) has become an indispensable method for probing the structure and composition of heterogeneous catalysts, revealing the nature of the active sites and establishing links between structural motifs in a catalyst, local electronic structure, and catalytic properties. Here we discuss the fundamental principles of the XAS method and describe the progress in the instrumentation and data analysis approaches undertaken for deciphering X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra. Recent usages of XAS in the field of heterogeneous catalysis, with emphasis on examples concerning electrocatalysis, will be presented. The latter is a rapidly developing field with immense industrial applications but also unique challenges in terms of the experimental characterization restrictions and advanced modeling approaches required. This review will highlight the new insight that can be gained with XAS on complex real-world electrocatalysts including their working mechanisms and the dynamic processes taking place in the course of a chemical reaction. More specifically, we will discuss applications of in situ and operando XAS to probe the catalyst’s interactions with the environment (support, electrolyte, ligands, adsorbates, reaction products, and intermediates) and its structural, chemical, and electronic transformations as it adapts to the reaction conditions.

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Section: Xas: Physical Principlesmentioning

confidence: 99%

Section: Xas: Physical Principlesmentioning

confidence: 99%

“…The vertical dashed lines in panels c and d show the R -value corresponding to an average nearest neighbor Cu–O distance. See ref ( 25 ) for RMC details.…”

Section: Xas: Physical Principlesmentioning

confidence: 99%

Section: Xas: Physical Principlesmentioning

confidence: 99%

Section: Xas: Physical Principlesmentioning

confidence: 99%

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In Situ/Operando Electrocatalyst Characterization by X-ray Absorption Spectroscopy

2020

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Cationic Copper Species Stabilized by Zinc during the Electrocatalytic Reduction of CO₂ Revealed by In Situ X‐Ray Spectroscopy

Velasco‐Vélez

Poon

Gao

et al. 2023

Advanced Sustainable Systems

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Advanced in situ X‐ray absorption spectroscopy characterization of electrochemically co‐electrodeposited bi‐element copper alloy electrodes shows that zinc yields the formation of a stable cationic Cu species during the electroreduction of CO2 at high cathodic polarization. In contrast, the formation/stabilization of cationic Cu species in copper oxides, or doping Cu with another element, like Ni, is not possible. It is found that the pure and mixed Cu:Zn electrodes behave similarly in term of electrocatalytic selectivity to multi‐carbon products. At higher Zn concentrations the electrode behaves like the pure Zn catalyst, which indicates that the Cu cationic species do not have a significant influence on the selectivity to multi‐carbon products. It is found that in the non‐monotonically distribution of products is dominated in term of surface energy in which copper prefers the surface. Otherwise, this work highlights the importance of in situ characterization to uncover the mechanisms mediating the catalytic reactions in contrast to ex situ or post mortem analysis, which can be a source of misinterpretation.

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Redox‐Driven Cu─Pd Bond Formation to Enhance the Efficiency for Electroreduction of CO₂ to CO

Lai

Chu

Chang

et al. 2022

Adv Energy and Sustain Res

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The redox reaction as the driving force induces the dynamic structure of the electrocatalyst, which enhances the performance of the catalysis. Yet, it lacks the understanding of the influence of redox driving force on the transforming process, inhibiting obtaining the actual factor that determines the catalytic performance. Resorting to the pulse and in situ methodology, herein, the effect of spontaneous reoxidation on the structural transformation of the Cu–Pd bimetallic catalyst for CO2 electroreduction is investigated. During the pulse program, applying the open‐circuit voltage and cathodic potential intermittently oxidizes and reduces the Cu–Pd bimetallic catalyst, which systematically reveals the catalyst redox reaction imparting the increase in CO2‐to‐CO selectivity. Through in situ X‐ray absorption spectroscopy (XAS), the dynamic structure induced by the spontaneous reoxidation is unveiled, suggesting the Cu─Pd bond formation for the bimetallic catalyst with a higher Pd content. Such a reoxidation‐induced Cu─Pd bond enhances the CO faradaic efficiency to 88% with the CO current density of −132 mA cm−2. By the methodologies, a new perspective is provided to understand the redox‐driven dynamic structure and the corresponding effect on the product selectivity, which is a vital concept to design the new catalysts in the future.

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Linking the evolution of catalytic properties and structural changes in copper–zinc nanocatalysts using operando EXAFS and neural-networks

Abstract: A neural network is used to reveal composition-dependent structural evolution under operando conditions in CuZn nanocatalysts for CO2 electroreduction.

Cited by 66 publications

References 73 publications

In Situ/Operando Electrocatalyst Characterization by X-ray Absorption Spectroscopy

In Situ/Operando Electrocatalyst Characterization by X-ray Absorption Spectroscopy

Cationic Copper Species Stabilized by Zinc during the Electrocatalytic Reduction of CO₂ Revealed by In Situ X‐Ray Spectroscopy

Redox‐Driven Cu─Pd Bond Formation to Enhance the Efficiency for Electroreduction of CO₂ to CO

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Linking the evolution of catalytic properties and structural changes in copper–zinc nanocatalysts using operando EXAFS and neural-networks

Abstract: A neural network is used to reveal composition-dependent structural evolution under operando conditions in CuZn nanocatalysts for CO2 electroreduction.

Cited by 66 publications

References 73 publications

In Situ/Operando Electrocatalyst Characterization by X-ray Absorption Spectroscopy

In Situ/Operando Electrocatalyst Characterization by X-ray Absorption Spectroscopy

Cationic Copper Species Stabilized by Zinc during the Electrocatalytic Reduction of CO2 Revealed by In Situ X‐Ray Spectroscopy

Redox‐Driven Cu─Pd Bond Formation to Enhance the Efficiency for Electroreduction of CO2 to CO

Contact Info

Product

Resources

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Cationic Copper Species Stabilized by Zinc during the Electrocatalytic Reduction of CO₂ Revealed by In Situ X‐Ray Spectroscopy

Redox‐Driven Cu─Pd Bond Formation to Enhance the Efficiency for Electroreduction of CO₂ to CO