Ag⁺ Interference from Ag/AgCl Wire Quasi-Reference Counter Electrode Inducing Corrosion Potential Shift in an Oil-Immersed Scanning Micropipette Contact Method Measurement

Abstract

Quantitative scanning micropipette contact method measurements are subject to the deleterious effects of reference electrode interference. The commonly used Ag/AgCl wire quasi-reference counter electrode in the miniaturized electrochemical cell of the scanning micropipette contact method was found to leak Ag+ into the electrolyte solution. The reduction of these Ag+ species at the working electrode surface generates a faradaic current, which significantly affects the low magnitude currents inherently measured in the scanning micropipette contact method. We demonstrate that, during the microscopic corrosion investigation of the AA7075-T73 alloy using the oil-immersed scanning micropipette contact method, the cathodic current was increased by the Ag+ reduction, resulting in positive shifts of corrosion potentials. The use of a leak-free Ag/AgCl electrode or an extended distance between the Ag/AgCl wire and micropipette tip droplet eliminated the Ag+ contamination, making it possible to measure accurate corrosion potentials during the oil-immersed scanning micropipette contact method measurements.

Direct Electrochemical Visualization of the Orthogonal Charge Separation in Anatase Nanotube Photoanodes for Water Splitting

“…The meniscus was additionally stabilized with a mineral oil layer. Oil is used to stabilize electrochemical cells on hydrophilic surfaces − without their contamination, since oxide–water contact is thermodynamically more preferable than oxide–oil one, especially under UV radiation . The experimental test of mineral oil coating effect was described in Figure S15 in the Supporting Information.…”

“…The nanopipette was immediately withdrawn after contacting the sample surface to minimize surface moistening. For high-resolution imaging, the sample surface was additionally covered with the thin layer (<0.1 mm) of mineral oil (Nacalai) to prevent droplet spreading and decrease the signal noise. − …”

Portable Mobile Gait Monitor System Based on Triboelectric Nanogenerator for Monitoring Gait and Powering Electronics

“…Because of irregular mechanical motion, the output voltage ranges from 2 V to 25 V. According to these electrical signals, the gait can be capture and recognized. However, the electrical energy from TENG cannot directly power the electronics, which may cause micro electronic equipment overload and damage due to the overly high and irregular voltage [50][51][52]. In the future, the portable mobile gait monitor system will be integrated with more functions using a dedicated selfpowered ASIC.…”

Correlating Corrosion to Surface Grain Orientations of Polycrystalline Aluminum Alloy by Scanning Electrochemical Cell Microscopy

“…23,24 This prevents the droplet from evaporating and spreading, which significantly increases the stability of the droplet electrochemical cell. 22,23,25 Taking advantage of OI-SECCM, this work explored the correlation between corrosion and grain orientations of Al alloy AA7075-T73. For Al, the presence of a passive oxide film reduces the conductivity and reactivity of the surface, 26,27 resulting in extremely low currents in microscopic electrochemical measurements.…”