Nanoscale electrochemical charge transfer kinetics investigated by electrochemical scanning microwave microscopy

Awadein, Mohamed; Sparey, Maxwell; Grall, Simon; Kienberger, Ferry; Nicolas, Clément; Gramse, Georg

doi:10.1039/d2na00671e

Cited by 3 publications

(1 citation statement)

References 42 publications

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“…The confinement of the electrical interaction between the tip and the MUT allows for better lateral resolution, higher signal-to-noise ratio (SNR), and more accurate calibration, as we will discuss in section 2.2. Moreover, unshielded tips have significant limitations when employed for measurements in liquids [10], as the tip shaft and cantilever contribute to electrochemical reactions and the measured S-Parameter depends on the immersion depth. Probes with a shielded cantilever [11] to reduce the stray capacitance are commercially available (PrimeNano Inc.).…”

Section: Introductionmentioning

confidence: 99%

Coaxial tips for a scanning microwave microscope and its calibration with dielectric references

Eckmann,

Herzog,

Lin

et al. 2024

Meas. Sci. Technol.

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Scanning microwave microscopy is a combination of an atomic force microscope with a vector network analyzer to measure locally resolved impedances. The technique finds application in the realms of semiconductor industries, material sciences, or biology. To determine quantitative material properties from the measured impedances, the system must be calibrated. Transferring the calibration from the calibration substrate onto the material under test is strongly limited when using unshielded probes, as the electromagnetic coupling to the surroundings can reach several centimeters. This work reports the fabrication of coaxially shielded probes for a scanning microwave microscope and their integration into such an instrument. We discuss a calibration method with dielectric references, using a simulation-assisted 1-port VNA calibration algorithm. Uncertainty considerations of the measurement process are included and propagation throughout the algorithm is performed. The calibration is verified with an additional dielectric reference. As an application example, the results for a static-random-access memory sample are presented. We identified system-related drift and trace noise as the dominant contributors to the uncertainties of the calibrated results. The here presented shielded tips can broaden the application scope of scanning microwave microscopy, as they are door-openers for measurements in liquids.

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Section: Introductionmentioning

confidence: 99%

Coaxial tips for a scanning microwave microscope and its calibration with dielectric references

Eckmann,

Herzog,

Lin

et al. 2024

Meas. Sci. Technol.

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Plasmonic photocatalysts for enhanced solar hydrogen production: A comprehensive review

Vasseghian

Joo

2023

Fuel

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Electrified Nanogaps under an AC Field: A Molecular Dynamics Study

Tavakol,

Newbold,

Voïtchovsky

2024

J. Phys. Chem. C

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The organization and dynamics of ions and water molecules at electrified solid−liquid interfaces are generally well understood under static fields, especially for macroscopic electrochemical systems. In contrast, studies involving alternating (AC) fields tend to be more challenging. In nanoscale systems, added complexity can arise from interfacial interactions and the need to consider ions and molecules explicitly. Here we use molecular dynamics (MD) simulations to investigate the behavior of NaCl aqueous solutions at different concentrations confined in nanogaps under AC fields ranging from 10 MHz to 10 GHz. We explore the impact of the gap size (2−60 nm) and of the solid material composing the electrode (silica, charged silica, or gold). Analysis of the transient and stable responses of the system shows that the total transverse dipole M z,total formed by the water molecules and the ions across the gap is always able to counter the applied field regardless of AC frequency, NaCl concentration, or electrode material. As expected, the ions lag at higher frequencies, leading to a capacitive behavior. This effect is fully compensated by water dipoles that lead the field, reaching a maximum lead at a specific frequency which depends on salt concentration and gap size. Changing the gap size affects the magnitude of M z,total . Finally, the electrode material is shown to affect the electrolyte behavior in the gap region. We anticipate these results to be useful for nanoscale dielectric spectroscopy, including scanning probes.

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Nanoscale electrochemical charge transfer kinetics investigated by electrochemical scanning microwave microscopy

Abstract: We show how Microwave Microscopy can be used to probe local charge transfer reactions with unprecedented sensitivity, visualizing surface reactions with only a few hundred molecules involved. While microwaves are...

Cited by 3 publications

References 42 publications

Coaxial tips for a scanning microwave microscope and its calibration with dielectric references

Coaxial tips for a scanning microwave microscope and its calibration with dielectric references

Plasmonic photocatalysts for enhanced solar hydrogen production: A comprehensive review

Electrified Nanogaps under an AC Field: A Molecular Dynamics Study

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