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Spectroelectrochemical Devices for Monitoring of Intermediates and Products on Carbonbased Composite Electrodes
Vaněčková, Eva ; Šikula, M. ; Hrdlička, Vojtěch ; Sebechlebská, Táňa ; Kolivoška, Viliam
Spectroelectrochemistry (SEC), as an interdisciplinary field, provides us with more comprehensive information about electroactive molecules involved in charge transfer reactions. Commercially\navailable SEC cells most often have an incorporated platinum working electrode, which can limit the range of the usable potential window and, in addition, can complicate the analysis due to the\nabsorption phenomenon. In this work, we designed and manufactured two types of custom-made SEC cells employing optically transparent carbon-based working electrodes for UV-Vis monitoring of reactants and electrogenerated intermediates and products. The first SEC cell is entirely manufactured by 3D printing using fused deposition modeling (FDM) by combining optically transparent (PET) and electrically conductive (PLA-CB) filaments. The second SEC cell employs pencil graphite (PG) rods as the working electrode (PGE) and its body is manually assembled from quartz slides. The functionality of the FDM 3D printed SEC cell and manually assembled quartz SEC cell were verified by cyclic voltammetry with in situ UV-Vis spectroscopic absorption monitoring of ruthenium(III) acetylacetonate (Ru(ac)3) redox-active probe dissolved in an aqueous or non-aqueous deaerated solvent, respectively. Both presented cells enable complete redox reversible conversion and strictly oxygen-free conditions.
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3D-printed Electrodes with Nearly Ideal Charge Transfer Characteristics
Vaněčková, Eva ; Sebechlebská, Táňa ; Kolivoška, Viliam
3D printing is an outstanding manufacturing tool for prototyping customized designs at reduced time and costs, having found applications in fields such as medicine or the automotive industry. The development of printable electrically conductive composite materials brought a revolution to electrochemistry, with 3D-printed electrodes being intensively studied from the viewpoint of\nanalytical performance and stability. However, it is often reported that 3D-printed electrodes have poor charge transfer characteristics, typically due to limited exposure of the electrically conductive phase at the composite surface to the surrounding solution. In this work, we devise and apply simple electrochemical activation procedures that lead to a significant improvement of charge transfer characteristics of 3D printed electrodes.
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3D Printed Microfluidic Cell for Spectroelectrochemical Analysis
Šikula, M. ; Vaněčková, Eva ; Hromadová, Magdaléna ; Kolivoška, Viliam
Recent advances in fused deposition modeling 3D printing (FDM 3DP) enabled \nthe manufacture of customized spectroelectrochemical (SEC) devices. Despite significant progress, \nreported designs still rely on conventional optical components (windows and cuvettes). In this \nwork, we apply bi-material FDM 3DP combining electrically conductive and optically \ntranslucent filaments to manufacture a fully integrated microfluidic SEC device. Employing cyclic \nvoltammetric measurements with redox probes, we demonstrate that the platform allows SEC sensing of \nreactants, intermediates, and products of charge transfer reactions in an oxygen- free \nenvironment. Developed approaches pave the way for SEC d vices with dramatically\nreduced costs compared to currently available commercial platforms.\n
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Electrochemical Characterization of Self-Assembled Monolayers Containing Redox Switching Element
Nováková Lachmanová, Štěpánka ; Kocábová, Jana ; Vavrek, František ; Sebechlebská, Táňa ; Šebera, Jakub ; Kolivoška, Viliam ; Lukášek, J. ; Balzer, N. ; Valášek, M. ; Hromadová, Magdaléna
Adsorption properties of molecules containing [Ru(terpy)2]2+ and [Os(terpy)2]2+ redox switching element connected to the electrode surface by tripodal thiolate anchoring groups have been studied together with their charge transfer properties in the adsorbed form. STM-based current-voltage measurements confirmed that the conductance of self-assembled monolayer containing [Os(terpy)2]2+ redox switching element is lower than that containing [Ru(terpy)2]2+ element. This observation agrees with previously observed differences in the electron transfer rate constants of these molecules in their adsorbed state.
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Electrochemical Techniques in Monitoring of Nervous System Drugs
Choińska-Mlynarczyk, Marta ; Hrdlička, Vojtěch ; Skopalová, J. ; Šelešovská, R. ; Kolivoška, Viliam ; Navrátil, Tomáš
Drugs of the nervous system (ATC group N) belong generally to the most commonly (mis)used substances worldwide. Their determination and monitoring of these drugs and their metabolites in various body fluids or environmental matrices represent a challenge for analytical chemists. Our research is focused on the application of electrochemical methods in the monitoring of the most frequently prescribed and the newly introduced nervous system drugs of precisely specified structures and/or of defined properties. For toxicological and pharmacokinetic reasons, emphasis has been placed on investigating the reaction mechanisms of their metabolite formation. New or alternative to commonly used electroanalytical methods applicable for monitoring and characterization of target compounds in their pure state, in body fluids, wastewaters, and other environmental matrices, has been developed. To improve the chemometric parameters and sensing characteristics, attention was paid to the construction of new electrochemical sensors, detectors (e.g. screen-printed, 3D printed), or cells, based on (modified/unmodified) traditional or nontraditional materials, preferably usable at the point-of-care.
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Electrochemical Characterization of Molecular Conductors Containing Redox Switching Element
Nováková Lachmanová, Štěpánka ; Vavrek, František ; Sebechlebská, Táňa ; Šebera, Jakub ; Kolivoška, Viliam ; Lukášek, J. ; Balzer, N. ; Valášek, M. ; Mayor, M. ; Hromadová, Magdaléna
Electrochemical properties of new molecules containing tripodal anchor and redox switching\nelement have been studied by cyclic voltammetry and DFT quantum mechanical calculations.\nComparison of their redox properties with individual organometallic [Ru(terpy)2]2+t3+ and\n[Os(terpy)2]2+t3+ redox centers shows that covalently bonded tripodal anchor does not\ncompromise the reversibility of a redox process and has no effect on the stability of new\nmolecules. New molecular conductors have smaller HOMO-LUMO gap and both are oxidized\nat only slightly more positive potentials after tripodal substitution making them suitable for the\ndevelopment of molecular conductors with switching abilities.
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2-D simulations of electromigration processes
Kolivoška, Viliam ; Gaš, Bohuslav (advisor) ; Koval, Dušan (referee)
6 Abstract In the presented thesis we introduce a computational model that can be used for 2-D and 3-D computer simulations of experiments in electrophoresis. The simulations are carried out by the aid of the finite element method (FEM). In particular, commercially available program Comsol Multiphysics 3.3 is employed. A general shape of continuity equation is chosen to express the mass, electric charge, momentum and energy conservation law. Diffusion, migration and convection terms are taken into account when formulating the mass conservation law. Both external (driving voltage) and internal (diffusion currents) terms are considered in the electric charge conservation law. Both constant voltage mode and constant current mode can be handled. A solvent is regarded as an incompressible Newtonian fluid. Both pressure-driven and electroosmotic flows can be taken into consideration. The heat convection as well as the heat diffusion is governed by the energy conservation law. Both strong and weak electrolytes (of any attainable valency) may be regarded as system constituents. Furthermore, the model can handle the ionic strength correction if desired. A task may be assigned either in Cartesian or cylindrical coordinates. The presented model was employed to solve four particular tasks. The first one inspects the...
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