Degradation of Titanium Electrodes in the Alternating Polarity Electrolysis

Shlepakov, P. S.

doi:10.20964/2019.06.62

Cited by 9 publications

(7 citation statements)

References 29 publications

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“…It was concluded that Pt electrodes are destroyed mechanically by a local energy deposition due to the reaction between NBs near the electrode surface. Investigation of Ti electrodes revealed different mechanism of the degradation 37 . In this case the growth of titanium oxide on the electrode surface is responsible for the reduction of the Faraday current during the first minute of the AP process.…”

Section: Resultsmentioning

confidence: 99%

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Nanoreactors in action for a durable microactuator using spontaneous combustion of gases in nanobubbles

Uvarov

Svetovoy

2022

Sci Rep

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A number of recent studies report enhancement of chemical reactions on water microdroplets or inside nanobubbles in water. This finding promises exciting applications, although the mechanism of the reaction acceleration is still not clear. Specifically, the spontaneous combustion of hydrogen and oxygen in nanobubbles opens the way to fabricate truly microscopic engines. An example is an electrochemical membrane actuator with all three dimensions in the micrometer range. The actuator is driven by short voltage pulses of alternating polarity, which generate only nanobubbles. The device operation is, however, restricted by a fast degradation of the electrodes related to a high current density. Here it is demonstrated that the actuator with ruthenium electrodes does not show signs of degradation in the long-term operation. It is the only material able to withstand the extreme conditions of the alternating polarity electrolysis. This property is due to combination of a high mechanical hardness and metallic conductivity of ruthenium oxide. The actuator combines two features considered impossible: on-water catalysis and combustion in a microscopic volume. It provides an exceptional opportunity to drive autonomous microdevices especially for medical or biological applications.

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Section: Resultsmentioning

confidence: 99%

“…On one side, the energy deposition from exploding NBs provides significant local stresses 10 , 36 on chemically inert electrodes such as Pt. On the other side, harder materials are oxidised resulting in the reduction of the current 37 as it occurs for Ti.…”

Section: Introductionmentioning

confidence: 99%

Nanoreactors in action for a durable microactuator using spontaneous combustion of gases in nanobubbles

Uvarov

Svetovoy

2022

Sci Rep

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“…One has to note that for Ti electrodes the average current per pulse is reduced during a few minutes but then reaches a steady state. A special investigation [30] showed that the current decrease is related to growth of titanium oxide layer and during this growth there is disbalance between oxidation and reduction processes. Finally, the balance is reached due to presence of cracks and pores in the oxide layer.…”

Section: Resultsmentioning

confidence: 99%

Explosion of Microbubbles Generated by the Alternating Polarity Water Electrolysis

et al. 2019

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Water electrolysis with a fast change of polarity generates a high concentration of bulk nanobubbles containing H 2 and O 2 gases. When this concentration reaches a critical value, a microbubble pops up, which is terminated quickly in an explosion process. In this paper, we provide experimental information on the phenomenon concentrating on the dynamics of exploding microbubble observed from the top and from the side. An initial bubble with a size of 150 μ m expands to a maximum size of 1200 μ m for 150 μ s and then shrinks in the cavitation process. The sound produced by the event is coming from two sources separated in time: exploding bubble and cavitating bubble. The observed dynamics supports expansion of the bubble with steam but not with H 2 and O 2 mixture. A qualitative model of this puzzling phenomenon proposed earlier is refined. It is demonstrated that the pressure and temperature in the initial bubble can be evaluated using only the energy conservation law for which the driving energy is the energy of the combusted gas. The temperature in the bubble reaches 200 ∘ C that shows that the process cannot be ignited by standard combustion, but the surface-assisted spontaneous combustion agrees well with the observations and theoretical estimates. The pressure in the microbubble varies with the size of the merging nanobubbles and is evaluated as 10–20 bar. Large pressure difference between the bubble and liquid drives the bubble expansion, and is the source of the sound produced by the process. Exploding microbubbles are a promising principle to drive fast and strong micropumps for microfluidic and other applications.

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“…To Previous work has shown that exposing electrodes to a conductive solution at low frequencies can cause electrode degradation. 54,55 Seen in Figure 4.1, even after many uses at a high frequency, the electrodes in Figure 4.1C have not degraded to the degree of the electrodes in When compared to the new electrodes in Figure 4.1A, the used electrodes have also degraded, though this is expected after multiple uses at high voltages and frequencies. Thus, radio frequency current provides the least electrode degradation and is the preferred frequency range for E-NAAMP.…”

Section: Frequency Effect On Electrode Integritymentioning

confidence: 89%

Nucleic Acid Amplification Using Radio Frequency Electrokinetic Heating

Yost¹

2020

Preprint

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Microfluidic PCR is one of the most common and widely used sample preparation techniques. Most heating methods for microfluidic PCR are heated in one of two ways: (1) the reaction is pumped between different boundary-heating zones, or (2) stationary reaction chamber boundaries are heated by resistive heating elements. Both heating methods are subject to limitations of boundary-driven heating, where an inherent thermal gradient exists between heater and reaction. Therefore, there is a need to develop a simple and rapid PCR heating mechanism that is not subject to limitations of boundary-driven heating.Alternating current (AC) electrokinetics has many uses in microfluidics, from dielectrophoresis, the study of induced dipoles on a particle in an electric field, to electrokinetic fluid pumping, where conductivity and thermal gradients drive fluid flow. A common side effect I would also like to thank my lab mates Steven Doria and Edwin Lavi for introducing me to the fields of microfluidics and lithography. In addition, I would like to thank my other lab mates, Md Nazibul Islam for his assistance with device photography and COMSOL simulations, and Yuncheng (Max) Yu for taking SEM images of electrode chips. A general thanks goes to all of my lab mates for their support, wisdom, and advice. My thanks also extend to my previous scientific mentors at Colorado State University & Boston Biochem, where my passion for engineering and biotechnology grew into what it is today. Finally, I would like to thank my family and friends I have made through Chemical Engineering and Club Swimming for their support, laughter, and advice during my time at Texas A&M University. I could not have achieved what I did without them. vi CONTRIBUTORS AND FUNDING SOURCES Contributors This work was supervised by a thesis committee consisting of Professor Gagnon (advisor) & Professor Ugaz of the Department of Chemical Engineering and Professor Jain of the Department of Biomedical Engineering. COMSOL simulations of electrokinetic heating were performed in collaboration with Md Nazibul Islam. Additionally, various pictures for figures & diagrams were taken by Md Nazibul Islam. Scanning electron microscope (SEM) images of electrodes were taken by Yuncheng (Max) Yu. All other work conducted for this thesis was completed by the student independently,

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Degradation of Titanium Electrodes in the Alternating Polarity Electrolysis

Cited by 9 publications

References 29 publications

Nanoreactors in action for a durable microactuator using spontaneous combustion of gases in nanobubbles

Nanoreactors in action for a durable microactuator using spontaneous combustion of gases in nanobubbles

Explosion of Microbubbles Generated by the Alternating Polarity Water Electrolysis

Nucleic Acid Amplification Using Radio Frequency Electrokinetic Heating

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