Multioxide combinatorial libraries: fusing synthetic approaches and additive technologies for highly orthogonal electronic noses.

This study evaluates the performance advancement of electronic noses, on-chip engineered multisensor systems, exploiting a combinatorial approach. We analyze a spectrum of metal oxide semiconductor materials produced by individual methods of liquid-phase synthesis and a combination of chemical deposition and sol-gel methods with hydrothermal treatment. These methods are demonstrated to enable obtaining a fairly wide range of nanomaterials that differ significantly in chemical composition, crystal structure, and morphological features.

Poly(vinyl chloride)/Nanocarbon Composites for Advanced Potentiometric Membrane Sensor Design.

Polymer nanocomposites filled with carbon nanoparticles (CNPs) are a hot topic in materials science. This article discusses the current research on the use of these materials as interfacial electron transfer films for solid contact potentiometric membrane sensors (SC-PMSs). The results of a comparative study of plasticized poly (vinyl chloride) (pPVC) matrices modified with single-walled carbon nanotubes (SWCNTs), fullerenes-C60, and their hybrid ensemble (SWCNTs-C60) are reported.

Current Trends and Promising Electrode Materials in Micro-Supercapacitor Printing.

The development of scientific and technological foundations for the creation of high-performance energy storage devices is becoming increasingly important due to the rapid development of microelectronics, including flexible and wearable microelectronics. Supercapacitors are indispensable devices for the power supply of systems requiring high power, high charging-discharging rates, cyclic stability, and long service life and a wide range of operating temperatures (from -40 to 70 °C). The use of printing technologies gives an opportunity to move the production of such devices to a new level due to the possibility of the automated formation of micro-supercapacitors (including flexible, stretchable, wearable) with the required type of geometric implementation, to reduce time and labour costs for their creation, and to expand the prospects of their commercialization and widespread use.

Hydrothermal Synthesis of a Cellular NiO Film on Carbon Paper as a Promising Way to Obtain a Hierarchically Organized Electrode for a Flexible Supercapacitor.

The formation of a cellular hierarchically organized NiO film on a carbon paper substrate under hydrothermal conditions using triethanolamine as a base has been studied. The thermal behavior of the carbon paper substrate with the applied semi-product shell was studied using synchronous thermal analysis (TGA/DSC) and it was demonstrated that such modification of the material surface leads to a noticeable increase in its thermal stability. Using scanning electron microscopy (SEM), it was shown that the NiO film grown on the carbon fiber surface is characterized by a complex cellular morphology, organized by partially layered individual nanosheets of about 4-5 nm thickness and lateral dimensions up to 1-2 μm, some edges and folds of which are located vertically relative to the carbon fiber surface.

Low Temperature Chemoresistive Oxygen Sensors Based on Titanium-Containing TiCT and TiCT MXenes.

The chemoresistive properties of multilayer titanium-containing TiCT and TiCT MXenes, synthesized by etching the corresponding MAX phases with NaF solution in hydrochloric acid, and the composites based on them, obtained by partial oxidation directly in a sensor cell in an air flow at 150 °C, were studied. Significant differences were observed for the initial MXenes, both in microstructure and in the composition of surface functional groups, as well as in gas sensitivity. For single TiCT and TiCT MXenes, significant responses to oxygen and ammonia were observed.

Gas-Sensitive Properties of ZnO/TiCT Nanocomposites.

At present, a new class of 2D nanomaterials, MXenes, is of great scientific and applied interest, and their application prospects are very broad, including as effective doping components for receptor materials of MOS sensors. In this work we have studied the influence on the gas-sensitive properties of nanocrystalline zinc oxide synthesized by atmospheric pressure solvothermal synthesis, with the addition of 1-5% of multilayer two-dimensional titanium carbide TiCT, obtained by etching TiAlC with NaF solution in hydrochloric acid. It was found that all the obtained materials have high sensitivity and selectivity with respect to 4-20 ppm NO at a detection temperature of 200 °C.

Microplotter Printing of a Miniature Flexible Supercapacitor Electrode Based on Hierarchically Organized NiCoO Nanostructures.

The hydrothermal synthesis of a nanosized NiCoO oxide with several levels of hierarchical self-organization was studied. Using X-ray diffraction analysis (XRD) and Fourier-transform infrared (FTIR) spectroscopy, it was determined that under the selected synthesis conditions, a nickel-cobalt carbonate hydroxide hydrate of the composition M(CO)(OH)·0.11HO (where M-Ni and Co) is formed as a semi-product.

Hydrothermal Synthesis of Nickel Oxide and Its Application in the Additive Manufacturing of Planar Nanostructures.

The hydrothermal synthesis of nickel oxide in the presence of triethanolamine was studied. Furthermore, the relationship between the synthesis conditions, thermal behavior, crystal structure features, phase composition and microstructure of semi-products, and the target oxide nanopowders was established. The thermal behavior of the semi-products was studied using a simultaneous thermal analysis (in particular, using one that involved thermogravimetric analysis and differential scanning calorimetry, TGA/DSC).

Application of Titanium Carbide MXenes in Chemiresistive Gas Sensors.

The titanium carbide MXenes currently attract an extreme amount of interest from the material science community due to their promising functional properties arising from the two-dimensionality of these layered structures. In particular, the interaction between MXene and gaseous molecules, even at the physisorption level, yields a substantial shift in electrical parameters, which makes it possible to design gas sensors working at RT as a prerequisite to low-powered detection units. Herein, we consider to review such sensors, primarily based on TiCT and TiCT crystals as the most studied ones to date, delivering a chemiresistive type of signal.

Microextrusion Printing of Multilayer Hierarchically Organized Planar Nanostructures Based on NiO, (CeO)(SmO) and LaSrCoFeO.

In this paper, NiO, LaSrCoFeO (LSCF) and (CeO)(SmO) (SDC) nanopowders with different microstructures were obtained using hydrothermal and glycol-citrate methods. The microstructural features of the powders were examined using scanning electron microscopy (SEM). The obtained oxide powders were used to form functional inks for the sequential microextrusion printing of NiO-SDC, SDC and LSCF-SDC coatings with resulting three-layer structures of (NiO-SDC)/SDC/(LSCF-SDC) composition.

Atmospheric Pressure Solvothermal Synthesis of Nanoscale SnO and Its Application in Microextrusion Printing of a Thick-Film Chemosensor Material for Effective Ethanol Detection.

The atmospheric pressure solvothermal (APS) synthesis of nanocrystalline SnO (average size of coherent scattering regions (CSR)-7.5 ± 0.6 nm) using tin acetylacetonate as a precursor was studied.

Synthesis of ((CeO)(SmO))@NiO Core-Shell Type Nanostructures and Microextrusion Printing of a Composite Anode Based on Them.

The process of the hydrothermal synthesis of hierarchically organized nanomaterials with the core-shell structure with the composition ((CeO)(SmO))@NiO was studied, and the prospects for their application in the formation of planar composite structures using microextrusion printing were shown. The hydrothermal synthesis conditions of the (CeO)(SmO) nanospheres were determined, and the approach to their surface modification by growing the NiO shell with the formation of core-shell structures equally distributed between the larger nickel(II) oxide nanosheets was developed. The resulting nanopowder was used as a functional ink component in the microextrusion printing of the corresponding composite coating.

Microextrusion Printing of Hierarchically Structured Thick VO Film with Independent from Humidity Sensing Response to Benzene.

The process of VO oxide by the combination of sol-gel technique and hydrothermal treatment using heteroligand [VO(CHO)(CHO)] precursor was studied. Using thermal analysis, X-ray powder diffraction (XRD) and infra-red spectroscopy (IR), it was found that the resulting product was VO(B), which after calcining at 300 °C (1 h), oxidized to orthorhombic VO. Scanning electron microscopy (SEM) results for VO powder showed that it consisted of nanosheets (~50 nm long and ~10 nm thick) assembled in slightly spherical hierarchic structures (diameter ~200 nm).

Printing Technologies as an Emerging Approach in Gas Sensors: Survey of Literature.

Herein, we review printing technologies which are commonly approbated at recent time in the course of fabricating gas sensors and multisensor arrays, mainly of chemiresistive type. The most important characteristics of the receptor materials, which need to be addressed in order to achieve a high efficiency of chemisensor devices, are considered. The printing technologies are comparatively analyzed with regard to, (i) the rheological properties of the employed inks representing both reagent solutions or organometallic precursors and disperse systems, (ii) the printing speed and resolution, and (iii) the thickness of the formed coatings to highlight benefits and drawbacks of the methods.

Hydrothermal Synthesis of Ag Thin Films and Their SERS Application.

In this article, a facile, one-step method for the formation of silver thin-film nanostructures on the surface of AlO substrates using the hydrothermal method is proposed. The dependence of the SERS effect intensity of the formed films during the detection of methylene blue (MB) low concentrations on the synthesis conditions, additional temperature treatment, and laser radiation wavelength (532 and 780 nm) in comparison with similar dye films on commercial SERS substrates is shown. The detection limit of the analyte used for the indicated lasers is estimated.

Microplotter printing of planar solid electrolytes in the CeO-YO system.

The formation process for planar solid electrolytes in the CeO-YO system has been studied using efficient, high-performance, high-resolution microplotter printing technology, using functional ink based on nanopowders (the average size of crystallites was 12-15 nm) of a similar composition obtained by programmed coprecipitation of metal hydroxides. The dependence of the microstructure of the oxide nanoparticles obtained and their crystal structure on yttrium concentration has been studied using a wide range of methods. According to X-ray diffraction (XRD), the nanopowders and coatings produced are single-phase, with a cubic crystal structure of the fluorite type, and the electronic state and content of cerium and yttrium in the printed coatings have been determined using X-ray photoelectron spectroscopy (XPS).

Microplotter-Printed On-Chip Combinatorial Library of Ink-Derived Multiple Metal Oxides as an "Electronic Olfaction" Unit.

Information about the surrounding atmosphere at a real timescale significantly relies on available gas sensors to be efficiently combined into multisensor arrays as electronic olfaction units. However, the array's performance is challenged by the ability to provide orthogonal responses from the employed sensors at a reasonable cost. This issue becomes more demanded when the arrays are designed under an on-chip paradigm to meet a number of emerging calls either in the internet-of-things industry or in situ noninvasive diagnostics of human breath, to name a few, for small-sized low-powered detectors.

Pen plotter printing of ITO thin film as a highly CO sensitive component of a resistive gas sensor.

InO-10%SnO (ITO) thin films on various substrates have been obtained by pen plotter printing using a solution of hydrolytically active heteroligand complexes [M(CHO)(CHO)] (where М = In and Sn) as a functional ink. According to XRD and Raman spectroscopy, it has been established that the film has a bixbyite structure (space group Ia3/T), consists of particles with an average size of about 20 nm (according to SEM and AFM) and has a band gap of 3.57 eV.