Electrochemical Quartz Crystal Microbalance with Dissipation Monitoring (EQCM-D)

Electrochemical quartz crystal microbalance with dissipation (EQCM-D) has emerged as a powerful in situ technique to complement electrochemical experiments. Quartz crystal microbalance with dissipation (QCM-D) is a highly sensitive surface technique that monitors real-time changes occurring at surfaces with nano-level sensitivity. When combined with electrochemistry, it can provide information on mass and structural changes associated with electron transfer processes occurring at the electrode surface, such as electropolymerization, ion intercalation, corrosion, and electrodepostion. The unique ability of the QSense QCM-D technology to measure data at multiple harmonics has enabled characterization of rough/porous Li- ion battery electrodes on a mesoscopic scale (ref 5-8).

The QSense electrochemistry (EC) module (QEM 401) facilitates simultaneous QCM-D and electrochemistry measurements on the same surface. The EQCM-D setup offers great flexibility for conducting experiments under different conditions, for example, experiments can be performed in organic solvents and other harsh media. The entire EQCM-D set-up can be placed in a glove box using appropriate connectors. QSense offers a wide variety of sensor surfaces as electrode mimics. Customized sensor surfaces can be prepared to meet user’s requirements.

EQCM-D Experimental Set-up

Figure 1 shows pictures of the QSense Explorer (Figure 1A), QSense EC module QEM 401 (Figure 1B) and the QSense Explorer chamber with EC module mounted on it (Figure 1C). QSense EC module comes in a three-electrode configuration, where the sensor surface acts as the working electrode, a Pt plate is the counter electrode, and a customized low leak Ag/AgCl electrode is used as the reference electrode. It is possible to configure the module with a custom reference electrode for use with organic solvents. The module can also be used in a two-electrode configuration by sealing off the reference electrode port with the Teflon cap provided. Three of the ports shown in Figure 1 B are used to connect the three electrodes with the potentiostat. The two other ports are connected to inlet and outlet tubing and experiments can be operated in either flow or batch modes (Figure 1C).

Figure 1: (A) QSense Explorer instrument, (B) QSense EC module QEM 401, and (C) QCM-D electrochemistry set-up (Biolin Scientific)

Figure 2: Schematic diagram of EQCM-D set-up

The schematics in Figure 2 provides a detailed diagram of this setup; the QSense sensor mounted at the bottom serves as the working electrode; any changes happening at the surface in the electrochemical environment are measured in real time by monitoring the frequency (f) and dissipation (D) changes of the sensor crystal using QCM-D. The Pt ceiling acts as the counter electrode, and the reference electrode is mounted in the outlet flow close (~4-5 mm) to the working electrode.

QSense Window EC module, QWEM-401

For light sensitive EC experiments, Biolin Scientific provides a Window EC module QWEM 401equipped with a 1 mm thick sapphire glass window that allows optical access to sensor surface (Figure 3B). Onto the glass of the window EC module, a platinum ring electrode has been sputtered, which acts as the counter electrode (CE) (Figure 3C). The top electrode of the sensor acts as working electrode (WE). The reference electrode (RE) is placed in the outlet flow path.

Figure 3: (A) QCM-D Window electrochemistry set-up (B) QSense EC-Window module QWEM (C) picture of Pt counter electrode in QWEM, (Biolin Scientific)

The EQCM-D set-up allows combining QCM-D measurements with typical electrochemical experiments such as, cyclic voltammetry (CV), amperometry, voltammetry and electrochemical impedance spectroscopy (EIS).

Figure 4 shows example QCM-D and EC data collected during copper plating and stripping onto a QSense gold sensor in response to voltage cycling from +0.3 V to -0.5V at 50 mV/s 4 times. Copper sulfate solution (10 mM CuSO₄ in 0.1 M H₂SO₄) was used as electrolyte. The decrease in ∆f indicates mass building up on the surface while the increase in ∆D indicates the film’s viscoelastic character. Dissipation, in this case is relatively low compared to the change in ∆f indicating that the copper film was rigidly adsorbed to the surface. The copper plating and stripping process was reversible (Data is obtained from Biolin Scientific).

Figure 4: Frequency ∆f, Dissipation ∆D and current I response to cycling E from +0.3 V to -0.5 V to +0.5 V at 50 mV/s four times

Applications of EQCM-D:

The application of EQCM-D is constantly growing in almost every field where electrochemistry is being applied. Some examples include, energy storage, polymer films, biomolecules, biosensors, and corrosion.

Top 10 EQCM-D Publications in Energy storage

Read our application note: Characterizing Surfaces and Surface Reactions in Energy Storage

EQCM-D has been successfully used to characterize electrode materials for energy storage and conversion. The technique has also been used to analyze the formation, growth, and mechanical properties of solid electrolyte interphase (SEI) films under various conditions. The effect of variables, such as electrolyte composition, additives and contamination on electrode performance have been investigated under various electrochemical conditions. Following is a list of the current top 10 publications related to EQCM-D energy storage applications:

1. Narayan et al. Electrochemically Induced Changes in TiO2 and Carbon Films Studied with QCM-D, ACS Applied Energy Materials, 2020 3 (2), 1775-1783.
2. Zhang et al. Charge Storage Mechanism of a Quinone Polymer Electrode for Zinc-ion Batteries, Journal of the Electrochemical society, 2020 167, 070558
3. Shpigel et al. EQCM-D technique for complex mechanical characterization of energy storage electrodes: Background and practical guide, Energy Storage Materials, 2019, 21, 399-413.
4. Kitz, et al. Operando EQCM-D with simultaneous in situ EIS: New insights into interphase formation in Li-ion batteries, Anal. Chem. 2019, 91, 3, 2296–2303.
5. Shpigel et al. In Situ Real-Time Mechanical and Morphological Characterization of Electrodes for Electrochemical Energy Storage and Conversion by Electrochemical Quartz Crystal Microbalance with Dissipation Monitoring, Acc. Chem. Res. 2018, 51, 1, 69–79.
6. Levi et al. In Situ Porous Structure Characterization of Electrodes for Energy Storage and Conversion by EQCM-D: a Review, Electrochimica Acta, 2017, 232, 271-284.
7. Shpigel et al. In situ hydrodynamic spectroscopy for structure characterization of porous energy storage electrodes. Nature Mater, 2016, 15, 570–575.
8. Levi et al. Quartz Crystal Microbalance with Dissipation Monitoring (EQCM-D) for in-situ studies of electrodes for supercapacitors and batteries: A mini-review, Electrochemistry Communications, 2016, 67, 16-21.
9. Hubaud et al. Interfacial study of the role of SiO2 on Si anodes using electrochemical quartz crystal microbalance, Journal of Power Sources, 2015, 282, 639e644.
10. Yang et al. Quantification of the Mass and Viscoelasticity of Interfacial Films on Tin Anodes Using EQCM‑D ACS Appl. Mater. Interfaces, 2015, 7, 26585−26594.

Selected Polymer Film EQCM-D Studies

Several publications have reported the use of EQCM-D in studying electrochemically initiated nucleation and growth of polymer films as well as transport of charged species, solvent, and other neutrals which occurs during redox chemistry of these films. Here is a list of selected references:

1. Wang et al. Real-time insight into the doping mechanism of redox-active organic radical polymers, Nature Mater, 2019,18, 69–75.
2. Savva et al. Ionic-to-electronic coupling efficiency in PEDOT:PSS films operated in aqueous electrolytes, J. Mater. Chem. C, 2018, 6, 12023.
3. Persson et al. Electronic Control over Detachment of a Self-Doped Water-Soluble Conjugated Polyelectrolyte, Langmuir 2014, 30, 21, 6257–6266.
4. Nilsson et al. Electrochemical quartz crystal microbalance study of polyelectrolyte film growth under anodic conditions, Applied Surface Science, 2013, 280,783-79.
5. Schmidt et al. Electrochemically Controlled Swelling and Mechanical Properties of a Polymer Nanocomposite, ACS Nano, 2009, 3, 8, 2207–2216.

Biosensor and Biomolecular Adsorption by EQCM-D

Examples of EQCM-D applications in the field of biosensors where biomolecules are adsorbed onto the surface involve biasing the surface and monitoring the biomolecular response of redox proteins, cells, DNA, and many more

1. Aruã C. da Silva et al. Electrochemical quartz crystal microbalance with dissipation investigation of fibronectin adsorption dynamics driven by electrical stimulation onto a conducting and partially biodegradable copolymer, Biointerphases, 2020, 15, 021003.
2. Jhih‐Guang Wu et al. , In Situ Probing Unusual Protein Adsorption Behavior on Electrified Zwitterionic Conducting Polymers, Advance materials Interfaces, 2020
3. Xueling Quana et al. In-situ monitoring of potential enhanced DNA related processes using electrochemical quartz crystal microbalance with dissipation (EQCM-D), Electrochemistry Communications, 2014, 48, 111-114

Using EQCM-D for Corrosion

There are numerous publications reporting the use of electrochemical QCM-D in studying surface corrosion. The following paper reports the use of EQCM-D for analysis of electrode corrosion in a Polymer Electrolyte Membrane (PEM) fuel cell.

1. Wickman, B, Grönbeck, H, Hanarp, P, and Kasemo, B. Corrosion Induced Degradation of Pt/C Model Electrodes Measured with Electrochemical Quartz Crystal Microbalance, Journal of the Electrochemical Society 157 (4), B592-B598 (2010).

The examples listed above include many common applications of the EQCM-D technology. There are potentially many other applications we may have missed. If you have other EQCM-D examples your group is working on please contact us know and we can include them in our list.