Tunable ZnO nanostructures for ethanol sensing
TL;DR: In this article, a simple hydrothermal process without using any structure-directing reagent was used to synthesize ZnO nanostructures with different morphologies including nanorods, nanowires, and nanobrushes.
Abstract: In this study, ZnO nanostructures with different morphologies including nanorods, nanowires, and nanobrushes were synthesized by a simple hydrothermal process without using any structure-directing reagent. The samples were characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The influence of the preparation parameters on the morphology of ZnO is discussed. Gas-sensing properties of the materials were investigated. The results reveal that all the prepared nanostructured ZnO powders show high response to ethanol, among which, the three-dimensional nanobrushes show the highest response, demonstrating excellent potentiality for ethanol sensors.
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TL;DR: Novel acetone sensors with enhanced response, selectivity and stability have been fabricated successfully by using nanoarchitectures consisting of ZnO nanosheets and Pd nanoparticles.
Abstract: Porous and single crystalline ZnO nanosheets, which were synthesized by annealing hydrozincite Zn5(CO3)2(OH)6 nanoplates produced with a water/ethylene glycol solvothermal method, are used as building blocks to construct functional Pd–ZnO nanoarchitectures together with Pd nanoparticles based on a self-assembly approach. Chemical sensing performances of the ZnO nanosheets were investigated carefully before and after their surface modification with Pd nanoparticles. It was found that the chemical sensors made with porous ZnO nanosheets exhibit high selectivity and quick response for detecting acetone, because of the 2D ZnO nanocrystals exposed in (100) facets at high percentage. The performances of the acetone sensors can be further improved dramatically, after the surfaces of ZnO nanosheets are modified with Pd nanoparticles. Novel acetone sensors with enhanced response, selectivity and stability have been fabricated successfully by using nanoarchitectures consisting of ZnO nanosheets and Pd nanoparticles.
170 citations
TL;DR: In this article, a high-performance LPG sensing based on nanostructures of zinc oxide and zinc stannate is proposed for highperformance liquefied petroleum gas sensing.
Abstract: High-performance liquefied petroleum gas sensing based on nanostructures of zinc oxide and zinc stannate
91 citations
TL;DR: In this article, high crystalline ZnO hierarchical nanostructures were prepared at room temperature through the alkaline hydrolysis of zinc salt by the forced mixing of two immiscible solutions: Zn-nitrate aqueous solution and oleic-acid-dissolved n-hexane solution.
Abstract: Highly crystalline ZnO hierarchical nanostructures were prepared at room temperature through the alkaline hydrolysis of zinc salt by the forced mixing of two immiscible solutions: Zn-nitrate aqueous solution and oleic-acid-dissolved n-hexane solution. The oleic acid acted as a surfactant in the room-temperature formation of well-defined ZnO hierarchical nanostructures, which subsequently demonstrated a sensitive and selective detection of C 2 H 5 OH. The responses of these hierarchical nanostructures to 10–100 ppm C 2 H 5 OH ranged from 15.7 to 177.7, which were 7–9 times higher than those of the agglomerated nanoparticles.
62 citations
TL;DR: In this article, a simple solvent thermal process using methanol or ethanol as solvents was studied, and their gas-sensing properties were also investigated, and the morphology of ZnO micro-bullets synthesized in ethanol was similar to but more uniform than that of pure ZnOs microbullets.
Abstract: In this study, pure ZnO microbullets, ZnO–ZnFe2O4 composite, and ZnO–Fe2O3–ZnFe2O4 composite with micron structured balloons, rods, and particles were prepared by a simple solvent thermal process using methanol or ethanol as solvents. The influence of solvents on the composition and morphology of the products was studied, and their gas-sensing properties were also investigated. The morphology of ZnO microbullets synthesized in ethanol is similar to but more uniform than that of ZnO microbullets synthesized in methanol. The Fe-doped ZnO synthesized in ethanol contains many micron particles homogeneously dispersing on the surface of the microbullets, which is composed of hexagonal wurtzite ZnO and franklinite ZnFe2O4, while Fe-doped ZnO prepared in methanol consists of micron structured balloons, rods, and particles, which is composed of hexagonal wurtzite ZnO, hematite Fe2O3, and franklinite ZnFe2O4. Compared with pure ZnO and ZnO–ZnFe2O4 composite, the ZnO–Fe2O3–ZnFe2O4 composite presented high response, rapid response/recovery characteristics, good selectivity, and excellent stability to acetone at relatively low operating temperature of 190 °C. This sensor could detect acetone in wide range of 1–1000 ppm, which was expected to be a promising gas sensor for detecting acetone.
46 citations
TL;DR: Using zinc naphthenate dissolved in xylene as a precursor undoped ZnO nanopowders were synthesized by the flame spray pyrolysis technique and showed a great selectivity towards NO2 at high working temperature, while small resistance variations were observed for C2H5OH and SO2, respectively.
Abstract: Using zinc naphthenate dissolved in xylene as a precursor undoped ZnO nanopowders were synthesized by the flame spray pyrolysis technique. The average diameter and length of ZnO spherical and hexagonal particles were in the range of 5 to 20 nm, while ZnO nanorods were found to be 5–20 nm wide and 20–40 nm long, under 5/5 (precursor/oxygen) flame conditions. The gas sensitivity of the undoped ZnO nanopowders towards 50 ppm of NO2, C2H5OH and SO2 were found to be 33, 7 and 3, respectively. The sensors showed a great selectivity towards NO2 at high working temperature (at 300 °C), while small resistance variations were observed for C2H5OH and SO2, respectively.
41 citations
References
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TL;DR: In this paper, the photoconducting properties of individual semiconductor nanowires are explored and the authors show the possibility of creating highly sensitive nanowire switches by exploring the photocconducting properties.
Abstract: no attention has been given to the photoconducting properties of nanowires despite the exciting possibilities for use in optoelectronic circuits. Here, we show the possibility of creating highly sensitive nanowire switches by exploring the photoconducting properties of individual semiconductor nanowires. The conductivity of the ZnO nanowires is extremely sensitive to ultraviolet light exposure. The light-induced conductivity increase allows us to reversibly switch the nanowires between “OFF” and “ON” states, an optical gating phenomenon analogous to the commonly used electrical gating. [2,3,10]
2,208 citations
TL;DR: In this article, the growth mechanism and growth habit of oxide crystals are investigated from a kinetics viewpoint, starting from the hypothesis of growth unit, and a new rule concerning the growth habit is deduced considering the relation between the growth rate and the orientation of the coordination polyhedron at the interface.
1,080 citations
TL;DR: A variety of novel hierarchical nanostructures with 6-, 4-, and 2-fold symmetries have been successfully grown by a vapor transport and condensation technique.
Abstract: A variety of novel hierarchical nanostructures with 6-, 4-, and 2-fold symmetries have been successfully grown by a vapor transport and condensation technique. It was found that the major core nano...
836 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
TL;DR: In this paper, the photoluminescence spectrum of the ZnO/AAM assembly system depends on the excitation wavelength in the visible region, which is attributed to different types of oxygen vacancies in the znO nanowires.
551 citations