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In Situ Induction Heating of Electrodes and ApplicationsRahman, Mohammad Azizur 10 August 2018 (has links)
This thesis describes the fabrication of an induction heating apparatus and its use to directly heat small platinum and gold electrodes in electrolyte solution. The heating characteristics of the electrodes were studied via the entropic shift of redox potential with temperature and change in Faradaic current. Temperature pulse voltammetry (TPV) and cyclic voltammetry were used for temperature calibration under various heating conditions. The maximum temperature reached at a 0.25 mm diam platinum electrode surface in solution was 84 degrees C. At heated electrodes an increase in current was found to be due to convection and diffusion. TPV was performed with inductively heated gold (0.5 mm diam) and platinum electrodes, which gave complete current-potential-temperature information. Induction heated Pt electrodes were employed to investigate the kinetics and mass transfer process of oxygen reduction reaction (ORR) in acidic and alkaline media.
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Electrochemical studies of external forcing of periodic oscillating systems and fabrication of coupled microelectrode array sensorsClark, David 01 May 2020 (has links)
This dissertation describes the electrochemical behavior of nickel and iron that was studied in different acid solutions via linear sweep voltammetry, cyclic voltammetry, and potentiostatic measurements over a range of temperatures at specific potential ranges. The presented work displays novel experiments where a nickel electrode was heated locally with an inductive heating system, and a platinum (Pt) electrode was used to change the proton concentration at iron and nickel electrode surfaces to control the periodic oscillations (frequency and amplitude) produced and to gain a greater understanding of the systems (kinetics), oscillatory processes, and corrosion processes. Temperature pulse voltammetry, linear sweep voltammetry, and cyclic voltammetry were used for temperature calibration at different heating conditions. Several other metal systems (bismuth, lead, zinc, and silver) also produce periodic oscillations as corrosion occurs; however, creating these with pure metal electrodes is very expensive. In this work, metal systems were created via electrodeposition by using inexpensive, efficient, coupled microelectrode array sensors (CMASs) as a substrate. CMASs are integrated devices with multiple electrodes that are connected externally in a circuit in which all of the electrodes have the same amount of potential applied or current passing through them. CMASs have been used for many years to study different forms of corrosion (crevice corrosion, pitting corrosion, intergranular corrosion, and galvanic corrosion), and they are beneficial because they can simulate single electrodes of the same size. The presented work also demonstrates how to construct CMASs and shows that the unique phenomena of periodic oscillations that can be created and studied by using coated and bare copper CMASs. Furthermore, these systems can be controlled by implementing external forcing with a Pt electrode at the CMAS surface. The data from the single Ni electrode experiments and CMAS experiments were analyzed by using the Nonlinear Time-Series Analysis approach.
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