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Controlled Growth of Vertically Oriented Trilayer MoS <sub/>2</sub> Nanoflakes for Rooma??Temperature NO <sub/>2</sub> Gas Sensor Applications
摘要： In present work, we introduce the controlled synthesis of few layer vertically oriented MoS2 flakes for high performance NO2 gas sensor applications. The density and the thickness of MoS2 nanosheets are controlled by varying the heating rate of the chemical vapor deposition process. Our study confirms that the nanoflakes of about three layers were obtained under the heating rate of 5 oC by using powders of MoO3 and S as precursors without using any catalyst. This is very advantageous because no catalyst was used, there was no need of buffer layer at the bottom of the MoS2 thin film flacks, thus omitting the leakage current when measuring the electrical signal and enhancing the gas sensing performance. Gas sensing measurements demonstrated that the interconnected vertically oriented MoS2 nanoflakes have a good response value of 20.1% to 0.5 ppm NO2 at RT, and 1.73% at 150 oC. The sensor showed full recovery characteristic at a measured temperature of 150 oC with response and recovery time of about 15 s, and 100 s, respectively. The sensor also exhibited good selectivity with the ignorable response to SO2, H2, NH3, H2S and a low detection limit of 42 ppb.
关键词： Few-layer MoS2,Gas sensors,Chemical vapor deposition,Vertically oriented
更新于2025-09-23 15:19:57
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Properties of Nitrogen/Silicon Doped Vertically Oriented Graphene Produced by ICP CVD Roll-to-Roll Technology
摘要： Simultaneous mass production of high quality vertically oriented graphene nanostructures and doping them by using an inductively coupled plasma chemical vapor deposition (ICP CVD) is a technological problem because little is understood about their growth mechanism over enlarged surfaces. We introduce a new method that combines the ICP CVD with roll-to-roll technology to enable the in-situ preparation of vertically oriented graphene by using propane as a precursor gas and nitrogen or silicon as dopants. This new technology enables preparation of vertically oriented graphene with distinct morphology and composition on a moving copper foil substrate at a lower cost. The technological parameters such as deposition time (1–30 min), gas partial pressure, composition of the gas mixture (propane, argon, nitrogen or silane), heating treatment (1–60 min) and temperature (350–500 ?C) were varied to reveal the nanostructure growth, the evolution of its morphology and heteroatom’s intercalation by nitrogen or silicon. Unique nanostructures were examined by FE-SEM microscopy, Raman spectroscopy and energy dispersive X-Ray scattering techniques. The undoped and nitrogen- or silicon-doped nanostructures can be prepared with the full area coverage of the copper substrate on industrially manufactured surface defects. Longer deposition time (30 min, 450 ?C) causes carbon amorphization and an increased fraction of sp3-hybridized carbon, leading to enlargement of vertically oriented carbonaceous nanostructures and growth of pillars.
关键词： vertically oriented graphene (VOG),Li-ion battery,roll-to-roll technology,inductively coupled plasma chemical vapor deposition (ICP CVD),supercapacitor
更新于2025-09-19 17:15:36
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High Visible Response of Vertical TiO2 Nanoclusters-CdSe Linked by Cysteine
摘要： Vertically oriented single-crystal TiO2 nanoclusters in tetramethylammonium hydroxide solution were synthesized hydrothermally directly on Ti substrate. N-Type semiconducting CdSe nanoparticles were then introduced deep coating TiO2 nanocrystalss via a two-step procedure using cystein as a surface coupling agent, followed by a subsequent electrodeposition process from selenosulfite to form orderly interconnecting heterojunctions. A key result achievement is that although the TiO2 nanocrystalss are less than 1 μm long, under the help of the bifunctional 2-amino-3-sulfhydrylpropanoic acid molecule linking the acceptor and donor materials, the virtue of strong visible absorption of single crystal TiO2 nanoclusters were fully developed in addition of ultraviolet, so that the heterojunction electrode exhibits excellent photoresponse in photoelectrochemical cells to visible lights, whose contribution is rather significant compared with that of ultraviolet lights. Vertical nanoclusters have advantages of leading electrons directly into the metal Ti substrate while maintaining the large surface area towards the electrolyte. These highly ordered nanohybrids are expected to have potential applications in photochemical solar cells with high efficiency.
关键词： TiO2 nanocluster,Visible lights,Sensitization,CdSe,Vertically oriented
更新于2025-09-04 15:30:14