|
|
Impedance spectroscopy measurements in lead acid batteries
Holemář, Jan ; Bača, Petr (referee) ; Křivík, Petr (advisor)
The master thesis provides a brief introduction to the lead-acid batteries. The thesis describes an internal construction, electrochemical reactions inside the batery, the area of application and possible degradation effects. The next part deals with an analytic method of the measurement called electrochemical impedance spectroscopy. The thesis describes the principle of measurement, alternative equivalent circuits, the impedance of electrochemical cell and the analyse of recorded datas. In the practical part was assembled the functional lead-acid cell. After that, experimental measurement was passed on the lead-acid cell in discharge and in a different concentration of electrolyte. In the last part was created the simulation of treatment of an electrochemical cell in the development solution Agilent VEE and after that all the measurement results were compared with the simulation.
|
|
|
Nanostructured surfaces for electrochemical detection
Dzuro, Matej ; Hrdý, Radim (referee) ; Drbohlavová, Jana (advisor)
This work deals with the preparation of gold nanostructures for future usage in electrochemical sensors and biosensors, methods for their characterization and production. The emphasis is focused on the template-based electrodeposition method of gold and on study of the effect of manufacturing conditions on physical properties, mainly electrical and topological of nanostructures. Thesis is focused also on overall function and sensitivity of the gold nanostructured electrode.
|
|
|
Electrochemical Characterization of Nanostructured Surfaces Modified by Substancies with Thiol Bound
Urbánková, Kateřina ; Kynclová, Hana (referee) ; Hrdý, Radim (advisor)
This master thesis deals with nanotechnology, nanoparticles and nanostructured surfaces, electrochemical methods, especially voltammetry, cyclic voltammetry, electrochemical impedance spectroscopy and contact angle measurement. One part is focused on electrodes primarily nanostructured and modified by substancies with thiol bound. Tutorial for preparation of gold nanostructured electrods is introduced in practical section including SEM photos of electrode surface. Nanostructured and bare gold electrodes were modified by 11-mercaptoundecanoic acid, streptavidin, glycine and biotin and measured by cyclic voltammetry, electrochemical impedance spectroscopy and contact angle.
|
|
|
Impedance measurements of lead-acid accumulators
Vaculík, Sebastian ; Bača, Petr (referee) ; Abraham, Pavel (advisor)
The main aim of this paper is to contribute to the elucidation of electrochemical processes. These processes occur in the investigated experimental lead-acid cell. For this purpose, electrochemical impedance spectroscopy was used. There are two methods of measurement presented. First one is used to measure impedance between electrodes. Second one is used to measure impedance of collector ribs inside positive or negative electrode. The results are represented by electrical equivalent circuits, whose elements are described in detail in the theoretical part.
|
|
|
Optimalisation of coposite materials for civil engineering
Kazda, Tomáš ; Chladil, Ladislav (referee) ; Novák, Vítězslav (advisor)
This work is focused on optimalisation of coposite materials for civil engineering. In the theoretical part of the project is introduction of the composite materials and materials which are used for their production. There are also concerned their properties and possible application areas. In conclusion of theoretical part this project is a summary of the possible use of composite materials. The practical part compares the characteristics of the different types of composites made in terms of conductivity and the rate of corrosion.
|
|
|
Carbon based electrodes for supercapacitors
Moncoľ, Maroš ; Kunovjánek, Miroslav (referee) ; Dvořák, Petr (advisor)
This master thesis deals with supercapacitors based on electrical double layer and proper carbon electrodes for this type of supercapacitors. In theoretical part of work is described theory of supercapacitors, energy storage principles and their properties. In the next part are described carbon materials, their properties and electrochemical methods of measurements that we used. In the experimental part is described preparation of electrodes, results and conclusion.
|
|
|
Liquid electrolytes for supercapacitors
Bill, Jan ; Dvořák, Petr (referee) ; Sedlaříková, Marie (advisor)
This work deals with the preparation of liquid electrolytes from different types of aprotic solvents with the aim of their application as electrolytes in electrochemical supercapacitors. Different sorts of aprotic solvents have been chosen, in which the following forms of salts were used: LiBF4, LiClO4,LiPF6. In the next part of the work, the properties of these solvents were measured and the best electrolyte, according to the biggest possible capacity of the system, was chosen. In the theoretical part of this work, the physical principle of supercapacitors and their propeties are described. It deals with electrolytes, their division and with the properties that are appropriate for supercapacitors. The experimental part of the work describes the process of preparation of the samples of electrodes, electrolytes and the techniques of measuring their capacities.
|
|
|
Electrochemical characteristics of AZ31 and AZ61 magnesium alloys in Hanks‘ solutions
Minda, Jozef ; Wasserbauer, Jaromír (referee) ; Tkacz, Jakub (advisor)
This thesis deals with the characterization of electrochemical corrosion properties of magnesium alloys as promising materials for biomedical applications. The wrought alloys AZ31 and AZ61 were used and exposed to corrosive environments of Hanks solutions (SBF) to simulate environmental conditions in living organisms. For the evaluation of the surfaces was used scanning electron microscopy (SEM) with elemental analysis measured by energy-dispersive spectroscopy (EDS). Short-term (5 min) and long-term (72 h) corrosion tests were conducted in order to optimize the measurement methodology and obtain corrosion parameters - especially corrosion potential (Ekor), corrosion current density (ikor) and polarisation resistance (RP). To evaluation of the short-term tests were by potentiodynamic tests, namely the linear polarization (LP) test. Long-term tests were measured by electrochemical impedance spectroscopy (EIS). Effects of the composition of the alloys (AZ31 and AZ61), surface treatment (grinding and polishing) and the composition of the solution (SBF without Ca, Mg, and with Ca, Mg) were compared. Complex corrosion behaviour in time was characterized and corrosion mechanisms were discussed.
|
|
|
Electrochemical propertiesand thermal stability of cup-like shape gold nanostructures
Kynclová, H.
Nanostructured surfaces are useful in enlargement of electroactive area of sensing electrodes. The electrodes are very sensitive with maintaining small electrode geometry. In this study, surfaces modified by cup-like gold nanoparticles were fabricated by electrochemical methods. Subsequently, electrochemical properties and thermal stability of fabricated nanostructured electrodes were studied. Thereafter, the electrochemical results were compared with unmodified flat gold layer and contribution of nanostructuring was evaluated. Stability of nanoparticles after thermal vacuum and air pressure treatment was studied using scanning electron microscope. These results are useful for subsequent research of nanostructured sensors.
|
|
|
Studium transportu iontů přes modelové fosfolipidové membrány
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír
Synthetically prepared model phospholipid bilayers (PLBs) in the form of black membranes, vesicles or supported membranes, with incorporated ionophores or real ion channels (i.e., artificially synthesized or gained from real living cells, e.g. protoplasts) are promising for study and simulations of transporting processes across the real cell membranes and the membranes surrounding sub-cellular structures. The electrochemical methods were found to be very suitable and sensitive enough for characterization of such processes.
|
guest ::
