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3D printed materials for the electrochemical determination of biologically active compounds
Choińska, Marta Katarzyna ; Navrátil, Tomáš ; Hrdlička, Vojtěch
3D printing materials are relatively novel materials in electrochemistry,\nused for manufacturing of electrochemical cells, electrodes\netc. They have been widely used mainly for tailored, fast, inexpensive,\nand easy preparation of various equipment for analyses of\nbiologically active compounds. Various medicinal products and illicit\ndrugs belong to this broad group of analytes which need to be\nmonitored because of the possibility of (un)intentional overdose or\nrecreational consumption, which can cause serious side effects or\neven death. Due to this risk, we decided to focus our research on the\ndevelopment of new, sensitive, selective, and easily customizable 3D\nprinted sensors for the determination of some commonly used\nantidepressants, analgesics, and illicit drugs.
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IMPOSING BIAXIAL STRAIN ON 2D LAYERED MATERIALS BY LIQUID-INDUCED SWELLING OF SUPPORTING POLYMER
Sampathkumar, Krishna ; Pekárek, J. ; Frank, Otakar
2D layered materials promise to revolutionize the field of electronics, photonics, optoelectronics, energy storage, and sensing, etc. 2D materials have exceptional mechanical properties, with critical elongation >10%. Employing the strain to manipulate the electronic structure of these 2D materials could lead to further improvement of their implementation in many aspects. The ease of manipulation of their electronic structure can be one of the critical factors for their utilization in photonic devices. Apart from the strain, which decreases (increases) the bandgap energy at the rate of similar to 100 meV under 1% of biaxial tension (compression), also the layer number causes bandgap energy change of, e.g., 0.5 eV between bulk (1.3 eV) and monolayer MoS2 (1.8 eV). In our work, we focus on using the swelling behavior of PMMA/SU8 polymer in methanol to impose the strain on 2D layered materials. In the first trials, we have shown that it is possible to reach a strain gradient from 0 to similar to 0.5% of biaxial strain via simple swelling of polymer substrates, both for graphene [1] and transition metal di-chalcogenides (TMDC) like MoS2. Raman spectroscopy was used to probe the lattice strain in the materials through measuring changes of vibrational frequencies, and photoluminescence was used to probe the strain-induced bandgap character and energy in TMDC at room temperature. The surface corrugation of the 2D material after the soaking was recorded with the help of atomic force microscope (AFM).
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ELECTROCHEMICAL STUDY OF CuSCN INORGANIC HOLE-TRANSPORT MATERIAL FOR SOLAR CELLS PREPARED BY ELECTRODEPOSITION FROM AQUEOUS SOLUTION
Vlčková Živcová, Zuzana ; Mansfeldová, Věra ; Bouša, Milan ; Kavan, Ladislav
A comparative study is reported for electrodeposited copper(I) thiocyanate layers (ca. 500 nm) on two types of conductive/semiconductive substrates: i) carbon (boron-doped diamond_BDD, glass-like carbon_GC), and ii) carbon-free F-doped SnO2 conducting glass (FTO). SEM and Raman evidence that electrodeposition from aqueous solution results in homogenous CuSCN layers with dominant thiocyanate ion bounded to copper through its S-end (Cu−SCN bonding), as in spin-coated CuSCN layers. Electrochemical impedance spectroscopy (EIS) confirms the p-type semiconductivity of layers with a flatband potential from 0.1 to 0.18 V vs. Ag/AgCl depending on the substrate type, and the acceptor concentration (NA) of 5 x 1020cm-3 in all cases. The flatband potentials determined from Mott-Schottky plots (EIS) are in good agreement with the Kelvin probe measurements. The blocking quality of CuSCN layers was tested using Ru(NH3)63+/2+ redox probe. CuSCN deposited on BDD substrate exhibits better blocking properties compared to CuSCN deposited on FTO.
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Photocatalytic concrete screeds with self-cleaning and antimicrobial function
Bíbová, Hana ; Šubrt, Jan ; Pližingrová, Eva ; Jakubičková, M. ; Sázavská, T. ; Dohnálek, P. ; Hykrdová, Lenka ; Jirkovský, Jaromír
Photocatalytic concrete screeds with self-cleaning and antimicrobial function have been developed and tested. These building materials contain sand grains with deposited composite TiO2/SiO2 layers. Two types of the screeds, grey and white, were prepared and their photoactivity and material characteristics were compared. Commercial TiO2 photocatalysts from several manufacturers were employed. Effects of different parameters, such as temperature of the coated sand calcination, humidity, and surface abrasion, were followed. Mechanical properties of the screeds were analyzed by SEM/XRD microscopy. Photocatalytic activity was tested by means of NOx oxidation (ISO norm 22197-1/2007). Antibacterial activity was evaluated by modified ISO norm 27447/2009 with Bacillus subtilis as a model organism.
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THE PHOTOCATALYTIC ABATEMENT OF NOX IMISSIONS USING COMMERCIAL FUNCTIONAL COATING WITH POROUS MORPHOLOGY
Žouželka, Radek
Titanium dioxide is the most important photocatalysts used for purifying applications. It was the purpose of this study to investigate the photocatalytic activity of commercial Protectam FN (R) containing TiO2 nanoparticles towards NO and NO2. Experiments on concrete as a support for photocatalyst were carried out in two types of reactors with laminar and turbulent flow under ´´real world setting´´ conditions of temperature, relative humidity, irradiation and pollutant concentrations. The results showed that photocatalytic process significantly reduced both nitrogen oxides in the air. The decrease in the total concentration of nitrogen oxides on contact with the photocatalytic surface reached 20-50 %, i.e. at a concentration of 100 ppb the decrease in NO and NO2 was 20-50 ppb. The nitrogen oxides were oxidized up to their highest oxidation state, nitric acid ( or nitrates) and undesirable nitrous acid was not formed at all. The experimental study conducted showed that the photocatalytic oxidation on the surface of the photocatalytic Protectam FN (R) coating is an effective method for the removal of nitrogen oxides from contaminated air.
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Influence of electrode preparation on electrocatalytic activity of water soluble porphyrazine complex to hydrogen
Klusáčková, Monika ; Janda, Pavel ; Tarábková, Hana
The influence of electrode preparation and used electrode substrate on electrocatalytic activity of N, N`,N``,N```tetramethyl-tetra-3,4-pyridinopor-phyrazinocobalt (CoTmt-3,4-ppa) complex deposited on electrode surface for hydrogen reaction has been studied. Electrochemical deposition, spontaneous adsorption, and spin coating have been used to the modification of two different electrode substrates: annealed gold and highly oriented pyrolytic graphite. Prepared electrodes have been characterized using cyclic voltammetry, backscattering VIS spectroscopy and atomic force microscopy. The detailed comparison of surface morphology, surface coverage, surface roughness parameters, and thickness of deposited layers of CoTmt-3,4-ppa mediatoronhydrogen reaction has been investigated.
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Development of the poly(methylene blue) modified graphite electrodes for the electrochemical detection of hydrogen sulphide
Zlámalová, Magda ; Janda, Pavel ; Nesměrák, K.
A comparative study have been undertaken of the electropolymerization and electrochemical properties of deposited electroactive polymer on two different graphite electrode substrates: basal plane highly oriented pyrolytic graphite (HOPG) and pencil-graphite electrode (PGE). Poly(methylene blue) modified electrodes (HOPG/pMB and PGE/pMB) have been prepared by potential cycling in aqueous electrolyte solution containing methylene blue monomer. It has been found that electrochemical properties and electrocatalytic activity of deposited film are greatly influenced by the type of electrode substrate. Developed electrodes have been further investigated as potential sensors for hydrogen sulphide.
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A COMPARATIVE STUDY OF LIQUID- AND GAS-PHASE CYCLOPENTENE HYDRATION CATALYZED BY THE MCM-22 ZEOLITE
Krupka, J. ; Otmar, J. ; Pawlesa, Justyna
The study deals with technological aspects of the direct hydration of cyclopentene to cyclopentanol. The catalytic properties of the MCM 22 zeolite were studied in the case of cyclopentene hydration both in liquid and gas phases. MCM-22, unlike other solid acid catalysts, is highly selective for the formation of cyclopentanol in the liquid-phase hydration in the slurry arrangement. It suppresses completely the undesirable etherification of cyclopentanol and allows obtaining cyclopentanol with almost 99% selectivity. But the liquid-phase hydration was found to lead to rapid deactivation of the zeolite. The deactivation is caused mainly by a formation of carbon deposits in the pores of the zeolite. When hydrating in the gas phase on the fixed bed of granular catalyst, it could be easy to periodically reactivate the catalyst in situ. However, it has been found that the exceptional selectivity of MCM-22 to the cyclopentanol formation is characteristic only for the liquid-phase hydration. The reaction in the gas phase is unselective. Furthermore, the equilibrium conversion of cyclopentene to cyclopentanol in the gas-phase hydration has been found to be industrially unusable below 1 % (e.g. under atm. pressure, at 120 degrees C and with a molar ratio of cyclopentene to water 1: 5, it is as low as 0.3 %).
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