2. Articole
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Item Current Trends in Nanomaterials for Metal Oxide-Based Conductometric Gas Sensors: Advantages and Limitations—Part 2: Porous 2D Nanomaterials [Articol](2023) Korotcenkov, Ghenadii; Tolstoy, Valeri P.This article discusses the features of the synthesis and application of porous two-dimensional nanomaterials in developing conductometric gas sensors based on metal oxides. It is concluded that using porous 2D nanomaterials and 3D structures based on them is a promising approach to improving the parameters of gas sensors, such as sensitivity and the rate of response. The limitations that may arise when using 2D structures in gas sensors intended for the sensor market are considered.Item Thermal transport evolution due to nanostructural transformations in ga-doped indium-tin-oxide thin films [Articol](2021) Cocemasov, Alexandr; Brinzari, Vladimir; Jeong, Do-Gyeom; Korotcenkov, Ghenadii; Lee, Jong S.; Nika, Denis L.We report on a comprehensive theoretical and experimental investigation of thermal con- ductivity in indium-tin-oxide (ITO) thin films with various Ga concentrations (0–30 at. %) deposited by spray pyrolysis technique. X-ray diffraction (XRD) and scanning electron microscopy have shown a structural transformation in the range 15–20 at. % Ga from the nanocrystalline to the amorphous phase. Room temperature femtosecond time domain thermoreflectance measurements showed nonlinear decrease of thermal conductivity in the range 2.0–0.5 Wm−1 K−1 depending on Ga doping level. It was found from a comparison between density functional theory calculations and XRD data that Ga atoms substitute In atoms in the ITO nanocrystals retaining Ia-3 space group symmetry. The calculated phonon dispersion relations revealed that Ga doping leads to the appearance of hybridized metal atom vibrations with avoided-crossing behavior. These hybridized vibrations possess shortened mean free paths and are the main reason behind the thermal conductivity drop in nanocrystalline phase. An evolution from propagative to diffusive phonon thermal transport in ITO:Ga with 15–20 at. % of Ga was established. The suppressed thermal conductivity of ITO:Ga thin films deposited by spray pyrolysis may be crucial for their thermoelectric applications.Item Conductometric gas sensors based on metal oxides modified with gold nanoparticles : a review [Articol](Springer, 2016) Korotcenkov, Ghenadii; Brinzari, Vladimir; Cho, Beong K.This review (with 170 refs.) discusses approaches towards surface functionalizaton of metal oxides by gold nanoparticles, and the application of the resulting nanomaterials in resistive gas sensors. The articles is subdivided into sections on (a) methods for modification of metal oxides with gold nanoparticles; (b) the response of gold nanoparticle-modified metal oxide sensors to gaseous species, (c) a discussion of the limitations of such sensors, and (d) a discussion on future tasks and trends along with an outlook. It is shown that, in order to achieve significant improvements in sensor parameters, it is necessary to warrant a good control the size and density of gold nanoparticles on the surface of metal oxide crystallites, the state of gold in the cluster, and the properties of the metal oxide support. Current challenges include an improved reproducibility of sensor preparation, better long-term stabilities, and a better resistance to sintering and poisoning of gold clusters during operation. Additional research focused on better understanding the role of gold clusters and nanoparticles in gas-sensing effects is also required.Item Metal oxides for biomedical and biosensor applications [Articol](Elsevier, 2021) Mondal, Kunal; Korotcenkov, GhenadiiMetal Oxides for Biomedical and Biosensor Applications gives an in-depth overview of the emerging research in the biomedical and biosensing applications of metal oxides, including optimization of their surface and bulk properties. Sections cover biomedical applications of metal oxides for use in cell cultures, antibacterial and antimicrobial treatments, dental applications, drug delivery, cancer therapy, immunotherapy, photothermal therapy, tissue engineering, and metal oxide-based biosensor development. As advanced and biofunctionalized nano/micro structured metal oxides are finding applications in microfluidics, optical sensors, electrochemical sensors, DNA-based biosensing, imaging, diagnosis and analysis, this book provides a comprehensive update on the topic. Additional sections cover research challenges, technology limitations, and future trends in metal oxides and their composites regarding their usage in biomedical applications. © 2021 Elsevier Inc. All rights reserved.Item Ozone sensing by In2O3 films modified with rh: Dimension effect [Articol](MDPI, 2021) Korotcenkov, Ghenadii; Nehasil, VaclavWe considered the effect of coverage of the surface of In2O3 films with rhodium on the sensitivity of their electrophysical properties to ozone (1 ppm). The surface coverage with rhodium varied in the range of 0–0.1 ML. The In2O3 films deposited by spray pyrolysis had a thickness of 40–50 nm. The sensor response to ozone depends on the degree of rhodium coverage. This dependence has a pronounced maximum at a coverage of ~0.01 ML of Rh. An explanation is given for this effect. It is concluded that the observed changes are associated with the transition from the atomically dispersed state of rhodium to a 3D cluster state.Item XPS study of Rh/In2O3 system [Articol](Elsevier, 2021) Korotcenkov, Ghenadii; Brinzari, Vladimir; Nehasil, VaclavThe effect of surface modification of In2O3 films by rhodium atoms deposited by electron beam sputtering on the XP spectra is considered. The surface coverage with rhodium ranged from 0 to 0.1 ML. It was shown that the main changes in the XP spectra occur in the Rh3d region and are caused by the dimensional effect of rhodium particles. With an increase in the surface coverage with rhodium, Rh particles grow from an atomically dispersed state to relatively large clusters. As the particle size increases, its electronic structure tends to approach the state corresponding to the bulk Rh. Such a process is accompanied by a decrease in BE Rh3d5/2 by 0.3–0.6 eV, which behaviour depends on the surface structure of the used In2O3 films.Item Current trends in nanomaterials for metal oxide-based conductometric gas sensors: Advantages and limitations. part 1: 1D and 2D nanostructures [Articol](MDPI, 2020) Korotcenkov, GhenadiiThis article discusses the main uses of 1D and 2D nanomaterials in the development of conductometric gas sensors based on metal oxides. It is shown that, along with the advantages of these materials, which can improve the parameters of gas sensors, there are a number of disadvantages that significantly limit their use in the development of devices designed for the sensor market.Item Theoretical bases of the operation of nanoscale semiconducting gas sensors on the example of tin dioxide [Articol](CEP USM, 2019) Brînzari, Vladimir; Korotcenkov, Ghenadii; Damaschin, IonItem The role of Rh dispersion in gas sensing effects observed in SnO2 thin films [Articol](Elsevier, 2019) Korotcenkov, Ghenadii; Nehasil, V.In the present work the effect of surface modification by rhodium on the conductivity response of the SnO2 films to reducing gases such as CO and H2 and oxidizing gas ozone was analyzed. SnO2 films, subjected to surface modification, were deposited by spray pyrolysis, while Rh was deposited using a micro electron beam evaporation. The thickness of the Rh coating varied in the range of 0–0.1 ML. It was found that there is an optimal thickness of Rh, which gives an improvement in the sensor response and a decrease in the recovery time. An explanation of the observed effects was proposed. It was assumed that the atomically dispersed state of rhodium is most active in gas–sensing effects. The transformation from the atomic state to the cluster state reduces the efficiency of the surface functionalization of SnO2 with rhodium.Item How to Improve the Performance of Porous Silicon-Based Gas and Vapor Sensors? Approaches and Achievements [Articol](Wiley, 2019) Korotcenkov, Ghenadii; Rusu, E.It is shown that, along with the advantages, sensors based on porous silicon (PSi) have disadvantages that inhibit their widespread use. The parameters of PSi which can affect the performance of PSi-based sensors are considered in detail, and approaches are analyzed that allow for the improvement of the main characteristics of PSi-based gas and vapor sensors. It is concluded that despite the progress made in terms of improving the sensitivity, selectivity, and stability of PSi-based sensors, further research and development in this direction is necessary, as the existing methods do not provide the required stability of the characteristics and selectivity of their response.