morphology

The nature of the electrolyte cation is known to have a significant impact on electrochemical reduction of CO2 at catalyst|electrolyte interfaces. An understanding of the underlying mechanism responsible for catalytic enhancement as the alkali metal cation group is descended is key to guide catalyst development. *

In the article “Studying the cation dependence of CO2 reduction intermediates at Cu by in situ VSFG spectroscopy” Liam C. Banerji, Hansaem Jang, Adrian M. Gardner and Alexander J. Cowan use in situ vibrational sum frequency generation (VSFG) spectroscopy to monitor changes in the binding modes of the CO intermediate at the electrochemical interface of a polycrystalline Cu electrode during CO2 reduction as the electrolyte cation is varied. *

Three alkali metal cations have been chosen for analysis: K+, which is the most commonly used electrolyte cation for eCO2R, Cs+, which has been shown to give the greatest enhancement for C2+ products, and Na+, which shows poorer eCO2R performance than K+ whilst maintaining appreciable levels of C-based products. The ability of VSFG to study catalyst|electrolyte interfaces without the need for modifications, as required in the spectroelectrochemical studies mentioned in the article, which can fundamentally alter the electrodes activity, makes it an important tool to assess the mechanisms occurring on the pc-Cu electrodes routinely employed for eCO2R. *

A CObridge mode is observed only when using Cs+, a cation that is known to facilitate CO2 reduction on Cu, supporting the proposed involvement of CObridge sites in CO coupling mechanisms during CO2 reduction. Ex situ measurements show that the cation dependent CObridge modes correlate with morphological changes of the Cu surface. *

The results presented in the article suggest that a high level of bridge site formation is related to, or facilitated by, the Cu restructuring that happens as a result of the use of the Cs+ cations in the supporting electrolyte. Recent reports have indicated that multiple (bridge) bound CO may be electrochemically inert but this work builds on the emerging evidence that CObridge sites are a key intermediate in the CO–CO coupling step that is required for C2+ formation during eCO2R. *

NanoWorld Pointprobe® CONTR AFM probes for contact mode atomic force microscopy (AFM) were used to characterize the morphology of the CU electrode surface before bulk electrolysis and after bulk electrolysis.*

Fig. 5 from Liam C. Banerji et al. “Studying the cation dependence of CO2 reduction intermediates at Cu by in situ VSFG spectroscopy”: AFM images showing surface morphology of the Cu electrode surface (a) before bulk electrolysis, after bulk electrolysis in CO2 purged 0.5 M (b) NaHCO3, (c) KHCO3 and (d) CsHCO3 and also in (e) CO purged 0.5 M CsHCO3. Image analysis methods are described in the Experimental section.NanoWorld Pointprobe® CONTR AFM probes for contact mode atomic force microscopy (AFM) were used to characterize the morphology of the CU electrode surface before bulk electrolysis and after bulk electrolysis. — Fig. 5 from Liam C. Banerji et al. “Studying the cation dependence of CO2 reduction intermediates at Cu by in situ VSFG spectroscopy”: AFM images showing surface morphology of the Cu electrode surface (a) before bulk electrolysis, after bulk electrolysis in CO2 purged 0.5 M (b) NaHCO3, (c) KHCO3 and (d) CsHCO3 and also in (e) CO purged 0.5 M CsHCO3. Image analysis methods are described in the Experimental section of the original article.

*Liam C. Banerji, Hansaem Jang, Adrian M. Gardner and Alexander J. Cowan
Studying the cation dependence of CO2 reduction intermediates at Cu by in situ VSFG spectroscopy
Chemical Science 2024, 15, 2889-2897
DOI: https://doi.org/10.1039/D3SC05295H

The article “Studying the cation dependence of CO2 reduction intermediates at Cu by in situ VSFG spectroscopy” by Liam C. Banerji, Hansaem Jang, Adrian M. Gardner and Alexander J. Cowan is licensed under a Creative Commons Attribution 3.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third-party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/3.0/.

Ferroelectric polymer thin films crystallize in different phases and microstructures depending on fabrication conditions such as annealing temperature or layer deposition technique.*

In the article “Spherulite-like microstructure observed for spin-cast P(VDF-TrFE) thin films and their ferroelectric characteristics” Davide Disnan, Jonas Hafner, Michael Schneider and Ulrich Schmid demonstrate how the morphology of spin-cast poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) thin films changes as a function of annealing temperature from rice-like to spherulite-like microstructure, whereas the latter morphology is closer to the crystallization characteristic of poly(vinylidene-fluoride) (PVDF).*

Thin films of PVDF and P(VDF-TrFE) were analyzed at the nanometre-scale using atomic force microscopy. *

NanoWorld Pyrex-Nitride PNP-TR AFM probes were used for the ferroelectric characterization of the polymer thin films by atomic force microscopy. *

The displacement of the metal-ferroelectric-metal structure in response to the electric field applied was measured at one single point in the centre of the capacitor. For that purpose, the AFM cantilever (NanoWorld PNP-TR with a spring constant of k = 0.32 N/m made of silicon nitride (non-conductive cantilever for avoiding electrical interference caused by ground loops) was used.*

The deflection during the electrical stimulation was calibrated through the measurement of the inverse optical lever sensitivity of the probe. In order to avoid significant indentation effects, the silicon wafer surface surrounding the capacitor structure was used to land the cantilever for the calibration. *

Fig. 1 from «Spherulite-like microstructure observed for spin-cast P(VDF-TrFE) thin films and their ferroelectric characteristics» by D. Disnan et al: Spherulite-like microstructure of P(VDF-TrFE) and spherulite microstructure of PVDF. a, b Optical micrograph and AFM height image of the spherulite-like microstructure of P(VDF-TrFE). Features like needle-shaped crystals (NSC), nucleation centres (NC) and grain boundaries (GB) are highlighted on the spherulite-like microstructure surface. C ,d Analog for the spherulite microstructure of PVDF. NanoWorld Pyrex-Nitride AFM probes of the PNP-TR type were used for the Ferroelectric characterization of the polymer thin films. — Fig. 1 from «Spherulite-like microstructure observed for spin-cast P(VDF-TrFE) thin films and their ferroelectric characteristics» by D. Disnan et al:
Spherulite-like microstructure of P(VDF-TrFE) and spherulite microstructure of PVDF. a, b Optical micrograph and AFM height image of the spherulite-like microstructure of P(VDF-TrFE). Features like needle-shaped crystals (NSC), nucleation centres (NC) and grain boundaries (GB) are highlighted on the spherulite-like microstructure surface. C ,d Analog for the spherulite microstructure of PVDF.

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*Davide Disnan, Jonas Hafner, Michael Schneider and Ulrich Schmid
Spherulite-like microstructure observed for spin-cast P(VDF-TrFE) thin films and their ferroelectric characteristics
Polymer, Volume 272, 17 April 2023, 125840
DOI: https://doi.org/10.1016/j.polymer.2023.125840

The article “Spherulite-like microstructure observed for spin-cast P(VDF-TrFE) thin films and their ferroelectric characteristics” by Davide Disnan, Jonas Hafner, Michael Schneider and Ulrich Schmid is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/.