Nanopillar ZnO gas sensor for hydrogen and ethanol
TL;DR: Aligned zinc oxide nanorods were synthesized directly via a two-step solution approach on an Al2O3 tube, and were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) as mentioned in this paper.
Abstract: Aligned zinc oxide nanorods were synthesized directly via a two-step solution approach on an Al2O3 tube, and were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The zinc oxide nanorods prepared were uniform with diameters of 10–30 nm and lengths about 1.4 μm. The response Sr (= Ra/Rg) of the aligned zinc oxide nanorod sensor reached 18.29 and 10.41 to 100 ppm ethanol and hydrogen, respectively, which was a two-fold increase compared with that reported in literature, demonstrating the potential for developing stable and sensitive gas sensors.
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TL;DR: In this paper, the authors extensively review recent developments in this field, focusing the attention on the detection of some common VOCs, including acetone (C3H6O), acetylene (C2H2), benzene (C6H6), cyclohexene (Cyclohexenene) and 2-propanol (C7H8O), by means of conductometric solid state sensors based on nanostructured semiconducting metal oxides.
777 citations
TL;DR: This paper presents a meta-analyses of the chiral stationary phase transition of Na6(CO3)(SO4)/ Na2SO4 using a high-performance liquid chromatography apparatus for the determination of Na2CO3(SO4).
Abstract: Xin Zhou,†,‡ Songyi Lee,† Zhaochao Xu,* and Juyoung Yoon*,† †Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 120-750, Republic of Korea ‡Research Center for Chemical Biology, Department of Chemistry, Yanbian University, Yanjii 133002, People’s Republic of China Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Shahekou, Dalian, Liaoning, People’s Republic of China
631 citations
TL;DR: In this article, the authors present an up-to-date review of metal oxide materials research for gas sensors application, due to the great research effort in the field it could not cover all the interesting works reported, the ones that, according to the authors, are going to contribute to this field's further development were selected and described.
590 citations
TL;DR: The role of graphene in fabricating flexible gas sensors for the detection of various hazardous gases, including nitrogen dioxide, ammonia, hydrogen, hydrogen sulfide, carbon dioxide, sulfur dioxide, and humidity in wearable technology, is discussed.
Abstract: Wearable electronics is expected to be one of the most active research areas in the next decade; therefore, nanomaterials possessing high carrier mobility, optical transparency, mechanical robustness and flexibility, lightweight, and environmental stability will be in immense demand. Graphene is one of the nanomaterials that fulfill all these requirements, along with other inherently unique properties and convenience to fabricate into different morphological nanostructures, from atomically thin single layers to nanoribbons. Graphene-based materials have also been investigated in sensor technologies, from chemical sensing to detection of cancer biomarkers. The progress of graphene-based flexible gas and chemical sensors in terms of material preparation, sensor fabrication, and their performance are reviewed here. The article provides a brief introduction to graphene-based materials and their potential applications in flexible and stretchable wearable electronic devices. The role of graphene in fabricating ...
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TL;DR: A comprehensive review of the research progress in the last five years concerning hydrogen gas sensors based on SMO thin film and one-dimensional (1D) nanostructures is provided.
Abstract: Recently, the hydrogen gas sensing properties of semiconductor oxide (SMO) nanostructures have been widely investigated. In this article, we provide a comprehensive review of the research progress in the last five years concerning hydrogen gas sensors based on SMO thin film and one-dimensional (1D) nanostructures. The hydrogen sensing mechanism of SMO nanostructures and some critical issues are discussed. Doping, noble metal-decoration, heterojunctions and size reduction have been investigated and proved to be effective methods for improving the sensing performance of SMO thin films and 1D nanostructures. The effect on the hydrogen response of SMO thin films and 1D nanostructures of grain boundary and crystal orientation, as well as the sensor architecture, including electrode size and nanojunctions have also been studied. Finally, we also discuss some challenges for the future applications of SMO nanostructured hydrogen sensors.
365 citations
Cites background from "Nanopillar ZnO gas sensor for hydro..."
...Besides, the hydrogen sensing properties of ZnO nanopillar and NR arrays have also been investigated [117,118]....
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TL;DR: Remarkable surface wettability transition occurs with an inducement of ultraviolet (UV) for aligned ZnO nanorod films and this reversible effect is ascribed to the cooperation of the surface photosensitivity and the aligned nanostructure.
Abstract: Remarkable surface wettability transition occurs with an inducement of ultraviolet (UV) for aligned ZnO nanorod films. The inorganic oxide films, which show super-hydrophobicity (left), become super-hydrophilic (right) when exposed to UV illumination. After the films are placed in the dark, the wettability evolves back to super-hydrophobicity. This reversible effect is ascribed to the cooperation of the surface photosensitivity and the aligned nanostructure. Such special property will greatly extend the applications of ZnO films.
1,137 citations
1,010 citations
TL;DR: The development of photochemical NO2 sensors that work at room temperature and are based on individual single-crystalline SnO2 nanoribbons are reported, which once again demonstrate that seemingly small variations in ligand structure can result in significant improvements in catalysis.
Abstract: A major area of application for nanowires and nanotubes is likely to be the sensing of important molecules, either for medical or environmental health purposes. The ultrahigh surface-to-volume ratios of these structures make their electrical properties extremely sensitive to surface-adsorbed species, as recent work has shown with carbon nanotubes,[1, 2] functionalized silicon nanowires and metal nanowires.[3, 4] Chemical nanosensors are interesting because of their potential for detecting very low concentrations of biomolecules or pollutants on platforms small enough to be used in vivo or on a microchip. Here we report the development of photochemical NO2 sensors that work at room temperature and are based on individual single-crystalline SnO2 nanoribbons. Tin dioxide is a wide-bandgap (3.6 eV) semiconductor. For n-type SnO2 single crystals, the intrinsic carrier concentration is primarily determined by deviations from stoichiometry in the form of equilibrium oxygen vacancies, which are predominantly atomic defects.[5] The electrical conductivity of nanocrystalline SnO2 depends strongly on surface states produced by molecular adsorption that results in space-charge layer changes and band modulation.[6] NO2, a combustion product that plays a key role in tropospheric ozone and smog formation, acts as an electron-trapping adsorbate on SnO2 crystal faces and can be sensed by monitoring the electrical conductance of the material. Because NO2 chemisorbs strongly on many metal oxides,[7] commercial sensors based on particulate or thin-film SnO2 operate at 300 ± 500 C to enhance the surface molecular desorption kinetics and continuously TMclean∫ the sensors.[8] The high-temperature operation of these oxide sensors is not favorable in many cases, particularly in an explosive environment. We have found that the strong photoconducting response of individual singlecrystalline SnO2 nanoribbons makes it possible to achieve equally favorable adsorption ± desorption behavior at room temperature by illuminating the devices with ultraviolet (UV) light of energy near the SnO2 bandgap. The active desorption process is thus photoinduced molecular desorption (Figure 1).[9] In conclusion, we have succeeded in the development of the ruthenium-based metathesis catalyst 4, which exhibits excellent metathesis activity, without any loss of stability in air. These findings once again demonstrate that seemingly small variations in ligand structure can result in significant improvements in catalysis.
913 citations
TL;DR: In this article, the mean grain size and lattice distortion of ZnO gas sensors were calculated with the Cauchy-Cauchy and Debye-Scherrer methods, respectively.
Abstract: Nanometer ZnO gas sensing material with different particle size were made by chemical precipitation, emulsion and microemulsion, respectively. Crystal structure and ceramic microstructure of powders were determined by XRD and TEM. The mean grain size and lattice distortion of the materials were calculated with the Cauchy–Cauchy and Debye–Scherrer methods, respectively. Gas sensitivity of ZnO to H2, SF6, C4H10, gasoline, C2H5OH was measured. It can be shown from experimental results that grain size of ZnO gas-sensitive materials can be controlled by means of different processes or surfactants. The gas sensitivity of ZnO gas sensor depends upon its grain size.
694 citations