In Situ Real-Time Monitoring of ITO Film under a Chemical Etching Process Using Fourier Transform Electrochemical Impedance Spectroscopy

Abstract

As a novel approach to the in situ real-time investigation of an ITO electrode during the wet etching process, step-excitation Fourier-transform electrochemical impedance spectroscopy (FT-EIS) was implemented. The equivalent circuit parameters (e.g., R ct, C dl) continuously obtained by the FT-EIS measurements during the entire etching process showed an electrode activation at the initial period as well as the completion of etching. The FT-EIS results were further validated by cyclic voltammograms and impedance measurements of partially etched ITO films using ferri- and ferrocyanide solution in combination with FESEM imaging, EDS, XRD analyses, and COMSOL simulation. We also demonstrated that this technique can be further utilized to obtain intact interdigitated array (IDA) electrodes in a reproducible manner, which is generally considered to be quite tricky due to delicacy of the pattern. Given that the FT-EIS allows for instantaneous snapshots of the electrode at every moment, this work may hold promise for in situ real-time examination of structural, electrokinetic, or mass transfer-related information on electrochemical systems undergoing constantly changing, transient processes including etching, which would be impossible with conventional electroanalytical techniques.

Multilayered NiMo/CoMn/Ni Cathodic Electrodes with Enhanced Activity and Stability toward Alkaline Water Electrolysis

“…Electrochemical impedance spectroscopy is a commonly used technique in electrical analysis, which is used to study the harmonic response of electrochemical systems . A simple one-dimensional line segment model was designed as shown in Figure S5, the length of the line segment L is related to the system diffusion coefficient ( D ) and the lowest frequency ( f min ) L = normal10 D 2 π f min It is assumed that the electrolyte does not affect the chemical reaction, the solution resistance is low enough, and assume that φ l = 0.…”

In Situ Real-Time Dendritic Growth Determination of Electrodeposits on Ultramicroelectrodes

“…Numerous studies have employed EIS to examine electrode surface roughness or electrode morphology. − However, traditional EIS is not suitable for dynamic systems such as an electrodeposition system due to data distortion originating from its prolonged data acquisition time. Multisine Fourier-transform electrochemical impedance spectroscopy (FTEIS), which utilizes a superposition of AC waves with varying frequency as the perturbation signal, substantially reduces the data acquisition time, collecting the impedance data relevant to the dynamic systems including electrochemical etching, electrodeposition, and so forth. , Given the noninvasive nature of electrochemical impedance spectroscopy, we suggest the implementation of multisine FTEIS to enable the in situ real-time monitoring of dendritic electrodeposition on microelectrodes. As the geometry of the electrode affects the diffusion properties of metal precursors, the low-frequency impedance data acquired by FTEIS contain the information about the dimension of the electrodeposit.…”

Imaging Metal/Metal Oxide Electrocatalyst Transformations in Liquids

“…Surface and interface structure of nanocrystals effect unique functional applications. The well-defined shape and structure influence structural stability and electrochemistry behaviors, their original states always change during the reaction conditions. − Therefore, in situ characterization techniques are expected to understand deeply mechanisms of designing well-defined nanocrystals and practical applications. − As such, in situ/operando spectroscopy techniques including X-ray analysis, Raman analysis, and nuclear magnetic resonance (NMR), among others, provide macroscale integral information and monitor material dynamics under operating conditions. − However, these spectroscopic techniques could not reveal the structural and chemical transformation mechanisms of metal oxide/metal nanocrystals, which is essential and urgent for understanding and controlling their properties to extend their electrochemical applications.…”