High-sensitivity electrochemical dual-QCM for reliable three-electrode measurements

TL;DR

This paper introduces a high-sensitivity dual electrochemical QCM system in a three-electrode setup, enabling simultaneous, accurate monitoring of mass changes on two electrodes despite damping challenges, with validation on silver deposition.

Contribution

The study presents a novel correction method and impedance calibration for dual EC-QCM, allowing reliable separation of mass and viscous effects on two electrodes in a three-electrode configuration.

Findings

Achieved mass detection of 412.2 ng on WE and 345.6 ng on CE during Ag deposition.

Validated the system with cyclic voltammetry and higher harmonic measurements.

Demonstrated potential for multi-electrode mass monitoring in energy storage applications.

Abstract

Electrochemical quartz crystal microbalance (EC-QCM) is a versatile gravimetric technique that allows for parallel characterization of mass deposition and electrochemical properties. Despite its broad applicability, simultaneous characterization of two electrodes remains challenging due to practical difficulties posed by the dampening from fixture parasitics and the dissipative medium. In this study, we present a dual electrochemical QCM (dual EC-QCM) that is employed in a three-electrode configuration to enable consequent monitoring of mass deposition and viscous loading on two crystals, the working electrode (WE) and the counter electrode (CE). A novel cor-rection approach along with a three standard complex impedance calibration is employed to overcome the effect of dampening while keeping high spectral sensitivity. Separation of viscous loading and rigid mass deposition is achieved by robust characterization of the complex impedance at the resonance frequency. Validation of the presented system is done by cyclic voltammetry characterization of Ag underpotential deposition on gold. The results indicate mass deposition of 412.2 ng for the WE and 345.6 ng for the CE, reflecting a difference of the initially present Ag adhered to the surface. We also performed higher harmonic measurements that further corroborate the sensitivity and reproducibility of the dual EC-QCM. The demonstrated approach is especially intriguing for electrochemical energy storage applications where mass detection with multiple electrodes is desired.