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Gas sensors based on diamond heterostructures for air quality monitoring
Kočí, Michal; Szabó, Ondrej; Izsák, T.; Sojková, M.; Godzierz, M.; Wróbel, P.; Husák, M.; Kromka, Alexander
2024 - anglický
Currently, great emphasis is placed on air quality and the presence of pollutants. Attention is therefore focused on new gas-sensing materials enabling detection even at low (up to room) temperatures with sufficient response and short reaction time. Here, we investigate the suitability of H-NCD films and their heterostructures with MoS2, GO, rGO, SH-GO, or Au NPs for gas sensing applications. Electrical properties are measured for oxidizing gas NO2, reducing gas NH3, and chemical vapor of ethanol, and at temperatures varied from room temperature to 125 °C. In contrast to the individual forms of employed materials with limited response to the exposed gases, the HNCD heterostructures revealed better sensing properties. In particular, the Au NPs/H-NCD heterostructures revealed a higher response at 125 °C in contrast to H-NCD, MoS2/H-NCD had quite good response even at room temperature and GO/H-NCD revealed high sensitivity to chemical vapor, which further improved for the SH-GO/HNCD.
Klíčová slova:
gas sensors; nanocrystalline diamond; heterostructures; air quality monitoring
Dokument je dostupný na externích webových stránkách.
Gas sensors based on diamond heterostructures for air quality monitoring
Currently, great emphasis is placed on air quality and the presence of pollutants. Attention is therefore focused on new gas-sensing materials enabling detection even at low (up to room) temperatures ...
Surface changes induced by plasma treatment and high temperature annealing of silicon dioxide microparticles
Babčenko, Oleg; Remeš, Zdeněk; Beranová, Klára; Kolářová, Kateřina; Lörinc, J.; Prošek, Z.; Tesárek, P.
2024 - anglický
Due to the high surface to volume ratio, the particles’ surface properties modification defines its properties in general, which is crucial for their use. From this point of view, plasma processing or high temperature annealing can be considered as the universal techniques for efficient modification of materials in the form of powder. In this study, the silicon dioxide microparticles have been treated in a hydrogen, oxygen or vacuum by low temperature plasma or annealing. The change of SiO2 microparticles properties was investigated by photoluminescence spectroscopy at room and low temperature. High temperature annealing in hydrogen induced under UV excitation photoluminescence in the near UV and visible light indicating the change of defect states on the surface of the microparticles. We believe that observed findings clearly demonstrate useful method for analysis of SiO2 microparticles surface modification attractive also for fundamental research.
Klíčová slova:
silicon dioxide; plasma treatment; annealing; photoluminescence; measuring setup
Dokument je dostupný na externích webových stránkách.
Surface changes induced by plasma treatment and high temperature annealing of silicon dioxide microparticles
Due to the high surface to volume ratio, the particles’ surface properties modification defines its properties in general, which is crucial for their use. From this point of view, plasma processing or ...
Room temperature ethanol detection using carbon materials
Kočí, Michal
2023 - anglický
Allotropic forms of carbon, in particular graphene oxide (GO) or nanocrystalline diamond (NCD), attracted the attention of many research groups due to their unique electronic structures and extraordinary physical and chemical properties, preferable for many different applications, including sensor devices. This work focuses on responses of various sensing layers (NCD with hydrogen termination (H-NCD), graphene oxide (GO), reduced graphene oxide (rGO), thiol-functionalized graphene oxide (GO-SH) and their hybrid structures to ethanol vapor with concentrations up to 100 ppm in synthetic air at room temperature. The measured parameters of the tested sensors, especially stability, reproducibility and regeneration, are compared and critically evaluated. The high sensitivity of tested sensors achieved at room temperature makes them very promising for monitoring ethanol vapor as well as other volatile substances (e.g., isopropyl-alcohol or acetone).
Klíčová slova:
gas sensor; nanocrystalline diamond (NCD); graphene oxide (GO); reduced graphene oxide (rGO); thiol-functionalized graphene oxide (GO-SH)
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Room temperature ethanol detection using carbon materials
Allotropic forms of carbon, in particular graphene oxide (GO) or nanocrystalline diamond (NCD), attracted the attention of many research groups due to their unique electronic structures and ...
Effect of spin coating on electrical properties of MXene films deposited from non-aqueous solvents
Gutsul, O.; Szabó, Ondrej; Pfeifer, R.; Sasitharan, K.; Jackivová, Rajisa; Slobodyan, V.; Kromka, Alexander; Rezek, B.
2023 - anglický
We investigated the effect of spin coating parameters on the electrical properties of Ti3C2 MXene thin films deposited from non-aqueous suspensions in N,N-dimethyl formamide (DMF) and N-methyl-2-pyrrolidone (NMP) on gold interdigitated electrodes (IDE). The electrical properties of DMF-MXenes and NMP-MXenes films are characterized by impedance spectroscopy (4 Hz - 8 MHz at 1 V) using gold IDE with 25 µm gap. The electrical conductivity of MXene films decreases with increasing spin coating speed from 300 to 900 rpm. The series resistance (Rs) and double layer capacitance remain similar (Cdl). In all cases, MXenes deposited from DMF have five orders of magnitude higher electrical conductivity (lower Rct) than MXene films deposited from NMP. It is correlated with the thin film morphology obtained by scanning electron microscopy (SEM). These findings can be useful for possible application of MXenes as charge transport layers in hybrid photovoltaic devices.
Klíčová slova:
MXene; thin films; impedance spectroscopy; electrical conductivity; spin coating
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Effect of spin coating on electrical properties of MXene films deposited from non-aqueous solvents
We investigated the effect of spin coating parameters on the electrical properties of Ti3C2 MXene thin films deposited from non-aqueous suspensions in N,N-dimethyl formamide (DMF) and ...
Enhanced growth rate of diamond films at low temperature in focused microwave plasma system
Babčenko, Oleg; Bydžovská, Irena; Fait, Jan; Shagieva, Ekaterina; Ondič, Lukáš; Kromka, Alexander
2023 - anglický
The low temperature (< 500 °C) diamond film deposition on fused silica in two different focused microwave plasma systems, i.e. a multimode clamshell cavity (MCC) and a rotational ellipsoid cavity (REC) reactor, was investigated. During the experiments, the methane to hydrogen ratio, in the hydrogen-rich process gas mixture, varied from 1 % to 15 % for MCC and from 1 % to 9 % for REC. The grown films were analyzed by scanning electron microscopy and Raman shift measurements. The outcomes of the study and enhanced diamond growth at low temperatures is advantageous for overcoating of fused silica as well as thermally sensitive substrates, e.g. optical elements, photonic crystals, sensors, etc.
Klíčová slova:
well-faceted diamonds; low temperature deposition; high growth rate; low non-diamond content; focused plasma
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Enhanced growth rate of diamond films at low temperature in focused microwave plasma system
The low temperature (...
Technological challenges in the fabrication of MoS.sub.2./sub./diamond heterostructures
Varga, Marián; Sojková, M.; Hrdá, J.; Hutar, P.; Parsa Saeb, S.; Vanko, G.; Pribusova Slusna, L.; Ondič, Lukáš; Fait, Jan; Kromka, Alexander; Hulman, M.
2023 - anglický
Nowadays, 2D materials are one of the most studied classes of materials. In addition to the most famous graphene, progress has been achieved in studying and using fundamental properties of transition metal dichalcogenides (TMD). Complementary, diamond as a representative of 3D materials has gained a reputation as an extremely versatile material due to its extraordinary combination of physical/chemical/electrical/optical properties. Besides these particular forms of 2D and 3D materials, their heterostructures have become very attractive due to new phenomena and functions (bandgap engineering, enhanced charge transport, optical interaction, etc.). However, individual technological procedures are still minimally investigated and described. Here, we will demonstrate a proof-of-concept for the preparation of MoS2/diamond heterostructures, where two different strategies were employed: a) growth of MoS2 layers on diamond films, and b) growth of diamond films on Si/MoS2 substrates.
Klíčová slova:
transition metal dichalcogenides; molybdenum disulfide; diamond; heterostructures
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Technological challenges in the fabrication of MoS.sub.2./sub./diamond heterostructures
Nowadays, 2D materials are one of the most studied classes of materials. In addition to the most famous graphene, progress has been achieved in studying and using fundamental properties of transition ...
Photo-active liquid crystalline materials: effect of lateral substitution far from the chiral center
Mironov, Sergei; Suchánek, T.; Marhoul, J.; Cigl, Martin; Hamplová, Věra; Bubnov, Alexej
2023 - anglický
Photosensitive liquid crystalline (LC) materials give a fascinating possibility to tune and control the optical properties of soft systems distantly by illumination by UV-Vis light. Lateral substitution on the molecular core is an effective tool to tune the behaviour of chiral LCs. The effect of lateral substitution (by F, Cl, Br and methyl group) on the self-assembling behaviour, several new LCs with substituents placed on the benzene ring far from the chiral centre are and studied. All compounds, with exception of Br-substituted one, possess the cholesteric phase. The photosensitive behaviour, in particular the conversion of the E-Z isomers, was studied in toluene solution by HPLC. The kinetics of the photo-isomerization was identified under illumination by UV light. Due to presence of a photo-active azo group these materials can be used as functional dopants for design of smart photo-active liquid crystalline mixtures targeted for various applications in optoelectronics.
Klíčová slova:
photosensitive chiral liquid crystal; lateral substitution; azobenzene; E-Z isomerization
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Photo-active liquid crystalline materials: effect of lateral substitution far from the chiral center
Photosensitive liquid crystalline (LC) materials give a fascinating possibility to tune and control the optical properties of soft systems distantly by illumination by UV-Vis light. Lateral ...
Termická analýza vstupních surovin pro růst krystalů vysokoteplotních komplexních oxidů
Zemenová, Petra; Král, Robert; Falvey, Alexandra; Pejchal, Jan; Bystřický, Aleš
2022 - český
Příspěvek se zabývá studiem tepelného chování oxidů vzácných zemin (La2O3, Sc2O3 a Gd2O3), které se používají jako výchozí suroviny při přípravě krystalů komplexních oxidů na bázi granátů a perovskitů, pomocí metod DSC-TG-MS. This contribution deals with the study of thermal behavior of oxide La2O3, Sc2O3 a Gd2O3 by methods DSC-TG-MS.
Klíčová slova:
thermal analysis DSC-TG; mass spectrometry; oxide; high-temperature complex oxides crystals
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Termická analýza vstupních surovin pro růst krystalů vysokoteplotních komplexních oxidů
Příspěvek se zabývá studiem tepelného chování oxidů vzácných zemin (La2O3, Sc2O3 a Gd2O3), které se používají jako výchozí suroviny při přípravě krystalů komplexních oxidů na bázi granátů a ...
Vliv velikosti zrn práškového NaCl na jeho termické vlastnosti
Falvey, Alexandra; Zemenová, Petra; Vaněček, Vojtěch; Bystřický, Aleš; Stehlík, Štěpán; Král, Robert
2022 - český
Příspěvek se zabývá studiem tepelného chování vzorku NaCl v práškové formě (s homogenní a nehomogenní distribucí zrn, různou vlhkostí) a monokrystalického NaCl metodami termické analýzy (DSC a TMA) a hmotnostní spektrometrii (MS). The paper deals with the study of the thermal behavior of a sample of NaCl in powder form (with homogeneous and inhomogeneous grain distribution, different humidity) and monocrystalline NaCl using the methods of thermal analysis (DSC and TMA) and mass spectrometry (MS).
Klíčová slova:
thermal analysis
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Vliv velikosti zrn práškového NaCl na jeho termické vlastnosti
Příspěvek se zabývá studiem tepelného chování vzorku NaCl v práškové formě (s homogenní a nehomogenní distribucí zrn, různou vlhkostí) a monokrystalického NaCl metodami termické analýzy (DSC a TMA) a ...
Tenké vrstvy pro fotovoltaiku nanášené plasmochemickými metodami
Fejfar, Antonín
2022 - český
Tenké vrstvy jsou klíčovou komponentou prakticky všech moderních fotovoltaických článků pro využití sluneční energie. Články využívají tenké vrstvy pro dosažení optimálního záchytu světla, pro rozdělení a sběr fotogenerovaných nábojů i pro pasivaci rozhraní či přímo jako vrstvy absorbující fotony slunečního svitu. Každoročně jsou tak nanášeny vrstvy o celkové ploše řádu mnoha stovek kilometrů čtverečních, a to především s využitím plazmochemických technologií. Thin films are key components for practically all of contemporary photovoltaic cells for solar energy utilization. Cells use thin films for optimizing light trapping, for selecting and collection of photogenerated charges and interface passivation or as absorber layers. Each year several hundreds of square kilometers of thin films are deposited mainly by plasma chemistry methods.
Klíčová slova:
thin films; deposition; plasma chemistry; photovoltaics
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Tenké vrstvy pro fotovoltaiku nanášené plasmochemickými metodami
Tenké vrstvy jsou klíčovou komponentou prakticky všech moderních fotovoltaických článků pro využití sluneční energie. Články využívají tenké vrstvy pro dosažení optimálního záchytu světla, pro ...
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