The Electro-Deposition/Dissolution of CuSO<sub>4</sub> Aqueous Electrolyte Investigated by <i>In Situ</i> Soft X-ray Absorption Spectroscopy

Velasco‐Vélez, Juan‐Jesús; Skorupska, Katarzyna; Frei, Elias; Huang, Yu‐Cheng; Dong, Chung‐Li; Su, Bing‐Jian; Hsu, Cheng-Kuei; Chou, Hung-Yu; Chen, Jin‐Ming; Strasser, Peter; Schlögl, Robert; Knop‐Gericke, Axel; Chuang, Cheng‐Hao

doi:10.1021/acs.jpcb.7b06728

Cited by 30 publications

(36 citation statements)

References 44 publications

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“…1c) not found in bulk sulfate solutions is not surprising. The similar observations but different interpretations have been reported very recently 27,28 indicating that further studies of this system are necessary.…”

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confidence: 73%

Interfacial Electrochemistry in Liquids Probed with Photoemission Electron Microscopy

et al. 2017

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Studies of the electrified solid-liquid interfaces are crucial for understanding biological and electrochemical systems. Until recently, use of photoemission electron microscopy (PEEM) for such purposes has been hampered by incompatibility of the liquid samples with ultrahigh vacuum environment of the electron optics and detector. Here we demonstrate that the use of ultrathin electron transparent graphene membranes, which can sustain large pressure differentials and act as a working electrode, makes it possible to probe electrochemical reactions in operando in liquid environments with PEEM.

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confidence: 73%

Interfacial Electrochemistry in Liquids Probed with Photoemission Electron Microscopy

et al. 2017

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“…Finally, after the electrochemical reduction of the deposited Cu film electrodes, the Cu oxidation state was deliberately controlled by linear sweep voltammetry (LSV) and concomitant recording of the electronic structure via in situ XAS at the Cu L2,3-edges ( Figure 1C). Stable Cu 2+ species were produced under anodic polarization where a significant amount of Cu 2+ dissolves due to a local reduction of the pH 27 . This dissolution diminished the thickness of the electrodeposited material somewhat.…”

Section: Resultsmentioning

confidence: 99%

The Role of the Copper Oxidation State in the Electrocatalytic Reduction of CO₂ into Valuable Hydrocarbons

Velasco‐Vélez

Jones

Gao

et al. 2018

ACS Sustainable Chem. Eng.

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Redox-active copper catalysts with accurately prepared oxidation states (Cu 0 , Cu + and Cu 2+) and high selectivity to C2 hydrocarbon formation, from electrocatalytic cathodic reduction of CO2, were fabricated and characterized. The electrochemically prepared copper-redox electro-cathodes yield higher activity for the production of hydrocarbons at lower oxidation state. By combining advanced X-ray spectroscopy and in situ micro-reactors it was possible to unambiguously reveal the variation in the complex electronic structure that the catalysts undergo at different stages (i.e. during fabrication and electrocatalytic reactions). It was found that the surface, sub-surface and bulk properties of the electrochemically prepared catalysts are dominated by the formation of copper carbonates on the surface of cupric-like oxides, which prompts catalyst deactivation by restraining effective charge transport. Furthermore, the formation of reduced or partially-reduced copper catalysts yields the key dissociative protonconsuming reactive adsorption of CO2 to produce CO; allowing the subsequent hydrogenation into C2 and C1 products by dimerization and protonation. These results yield valuable information on the variations in the electronic structure that redox-active copper catalysts undergo in the course of the electrochemical reaction, which, under extreme conditions are mediated by thermodynamics but, critically, kinetics dominate near the oxide/metal phase transitions.

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“…Anyhow, the dissolution process observed is different than the chemical dissolution observed during anodic polarization of copper electrodes. 29 In addition to the activity/selectivity tests, changes in the electrode morphology and surface roughness induced by the thermal oxidation in air and CO 2 RR were investigated by means of ex situ SEM analysis and ECSA measurements. Figure 2 B1–D1 shows the electrode morphology after the thermal treatment at different temperatures used to prepare the different electrodes of this investigation.…”

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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The Electro-Deposition/Dissolution of CuSO₄ Aqueous Electrolyte Investigated by In Situ Soft X-ray Absorption Spectroscopy

Cited by 30 publications

References 44 publications

Interfacial Electrochemistry in Liquids Probed with Photoemission Electron Microscopy

Interfacial Electrochemistry in Liquids Probed with Photoemission Electron Microscopy

The Role of the Copper Oxidation State in the Electrocatalytic Reduction of CO₂ into Valuable Hydrocarbons

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

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The Electro-Deposition/Dissolution of CuSO4 Aqueous Electrolyte Investigated by In Situ Soft X-ray Absorption Spectroscopy

Cited by 30 publications

References 44 publications

Interfacial Electrochemistry in Liquids Probed with Photoemission Electron Microscopy

Interfacial Electrochemistry in Liquids Probed with Photoemission Electron Microscopy

The Role of the Copper Oxidation State in the Electrocatalytic Reduction of CO2 into Valuable Hydrocarbons

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

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Product

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The Electro-Deposition/Dissolution of CuSO₄ Aqueous Electrolyte Investigated by In Situ Soft X-ray Absorption Spectroscopy

The Role of the Copper Oxidation State in the Electrocatalytic Reduction of CO₂ into Valuable Hydrocarbons

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