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TiO2 Nanotubes with Nanograss Structure: The Effect of the Anodizing Voltage on the Formation Mechanism and Structure Properties
摘要： Titanium dioxide nanotubes (TiO2 NTs) with a nanograss structure were synthesized in a fluoride organic electrolyte based on ethylene glycol under a potentiostatic anodization regime. By varying the anodization voltage, significant morphological differences were obtained, and the upper NTs’ surface has a nanograss appearance caused by the thinning of top tube walls, the result of the vertical splitting mechanism of nanograss growth. The samples were characterized using techniques such as scanning electron microscopy, x-ray diffraction, UV–visible spectroscopy and Mott–Schottky (MS) analysis. The obtained results show that samples annealed at 500°C for 3 h crystallized into anatase form and displayed the apparition of rutile phase at higher anodization voltage, where the morphology was significantly improved with thicker tube walls. The MS measurement of all samples displays a n-type semiconductor nature and the flat band potential (Ufb) takes less negative values by the increasing anodization voltage. As a result, TiO2 NTs with a nanograss structure expedite electron–hole separation, therefore, providing a lower recombination rate.
关键词： nanograss,TiO2 nanotubes,anodization process,nanomaterials,properties
更新于2025-09-23 15:22:29
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Gas Sensing with Iridium Oxide Nanoparticle Decorated Carbon Nanotubes
摘要： The properties of multi-wall carbon nanotubes decorated with iridium oxide nanoparticles (IrOx-MWCNTs) are studied to detect harmful gases such as nitrogen dioxide and ammonia. IrOx nanoparticles were synthetized using a two-step method, based on a hydrolysis and acid condensation growth mechanism. The metal oxide nanoparticles obtained were employed for decorating the sidewalls of carbon nanotubes. Iridium-oxide nanoparticle decorated carbon nanotube material showed higher and more stable responses towards NH3 and NO2 than bare carbon nanotubes under different experimental conditions, establishing the optimal operating temperatures and estimating the limits of detection and quantification. Furthermore, the nanomaterials employed were studied using different morphological and compositional characterization techniques and a gas sensing mechanism is proposed.
关键词： carbon nanotubes,relative humidity effect,metal nanoparticles,iridium oxide,chemoresistive gas sensor
更新于2025-09-23 15:22:29
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AIP Conference Proceedings [Author(s) PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM ON CURRENT PROGRESS IN MATHEMATICS AND SCIENCES 2017 (ISCPMS2017) - Bali, Indonesia (26–27 July 2017)] - Bismuth vanadate (BiVO4) as counter electrode in the newly developed catalysis zone of modified cadmium sulfide (CdS) sensitized solar cell for hydrogen production
摘要： Recently we developed a modified quantum dot dyes sensitized solar cell (QD-DSSC) having catalysis zone extension for hydrogen production. The DSSC section comprised of CdS sensitized highly order Titanium dioxidenanotube (CdS-HOTN) immobilized on Ti plate, Na2S/S containing electrolyte, and Pt covered SnO-F (fluorine doped tin oxide) glass plate (hence Pt/SnO-F/Glass). While the catalysis zone comprised of an extension of Ti support, as cathode, and the respected counter electrode was an extension of SnO-F glass, which was covered by BiVO4 film, both from respected DSSC section. In this presentation, we will focus on the role of the BiVO4 in our newly developed system. The bismuth vanadate was prepared by co-precipitation method with ammonia and calcination to obtain a fine powder. The BiVO4 fine powder were then deposited onto SnO-F glass plate and characterized by FT-IR, UV–vis diffused reflectance spectroscopy, SEM and X-ray diffraction. The characterization results revealed that the BiVO4 film, typically, has a band gap of 2.35 eV, characteristic of IR peaks represent the –V-O-, and –Bi-O-V- bonds, having a crystal phase as BiVO4 monoclinic scheelite with a typically crystallite size of 74.06 nm. The photo-electro-chemical properties of the BiVO4 film photo-anode was investigated by a linear sweep voltammetry and multi pulse amperometry, which revealed that the current response under the visible light was 0.03 mA/cm2. Further investigation when the BiVO4 film was incorporated into the modified QD-DSSC, the system (catalysis zone section), under solely visible light, was able to split the water into hydrogen and molecular oxygen. A brief discussion of the newly developed modified QD-DSSC, especially on the role of BiVO4 counter electrode in the catalysis zone will be presented, to gain a better insight in our new type artificial photosynthesis.
关键词： water splitting,titanium dioxide nanotubes,cadmium sulfide,artificial photosynthesis,modified dyes sensitized solar cell,Bismuth vanadate
更新于2025-09-23 15:21:21
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Switchable Photoacoustic Imaging of Glutathione Using MnO2 Nanotubes for Cancer Diagnosis
摘要： Glutathione is overexpressed in tumor cells and regulates cancer growth, metastasis and drug resistance. Therefore, detecting glutathione levels may greatly facilitate cancer diagnosis and treatment response monitoring. Photoacoustic (PA) imaging is a noninvasive modality for high-sensitivity, high-resolution, deep-tissue optical imaging. Switchable PA probes that offer signal on/off responses to tumor targets would further improve the detection sensitivity and signal-to-noise ratio of PA imaging. Here we explore the use of MnO2 nanotubes as a switchable and biodegradable PA probe for dynamic imaging of glutathione in cancer. Glutathione reduces black MnO2 nanotubes into colorless Mn2+ ions, leading to decreased and “signal off” PA amplitude. In phantoms, we observed a linear response of reduced PA signals of MnO2 nanotubes to increased glutathione concentrations. Using melanoma as the disease model, we demonstrated that MnO2 nanotubes-based PA imaging of glutathione successfully distinguished B16F10 melanoma cells from BEAS-2b normal cells and discriminated B16F10 tumors from healthy skin tissues. Our results showed that MnO2 nanotubes are a potent switchable and biodegradable PA probe for glutathione imaging in cancer diagnosis.
关键词： photoacoustic imaging,nanotubes,cancer,glutathione,melanoma,switchable contrast reagent,MnO2
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Stability of carbon nanotube cold cathode electron beam (C-beam) with vacuum brazing process
摘要： A modularization of electronic parts in electrical devices is a key feature for system integration. Especially, x-ray tube fabrication process has been stayed in an obsolete manner due to the utilizing of classical thermionic x-ray sources. But cold cathode emitters such as carbon based materials with nanoscale dimension are expected to replace the conventional wired tungsten filaments due to their outstanding electrical and mechanical properties. To facilitate cold cathode emitter as an x-ray source, state of the arts bonding techniques are required. In this study, carbon nanotube grown Si wafers were successfully bonded to the metal carrier via vacuum brazing process and no electrical degradation of CNT (carbon nanotubes) emitters were observed after the process. Finally, we evaluated the stability of electron beam current density for device reliability. We expect that the cost-effective and facile technique could be applied for cold cathode based x-ray tube manufacturing process.
关键词： carbon nanotubes (CNTs),brazing,x-ray tube,junction,cold cathode
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Effect of thermal pre-treatment on thermionic emission current stability from carbon nanotube forests
摘要： Carbon nanotube forests have great potential as efficient thermionic electron emitters due to a highly localized optical heating effect (“Heat Trap”). In past experiments, we observed a rapid decay in the emission current. In this work, we demonstrate that a relatively stable emission current can be achieved if the nanotube forest is pre-heated to 300 °C for 4 hours priors to electron emission. We attribute this improved current stability to the removal of reactant species, such as water trapped within the nanotube forest network.
关键词： Heat Trap,outgassing,lifetime,Carbon nanotubes,current stability,cathode,thermionic emission
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Fabrication of stable carbon nanotube cold cathode electron emitters with electrical aging
摘要： We studied on the fabrication and improved field emission properties of carbon nanotube (CNT) cold cathode electron emitters with electrical aging. Our CNT field emitters have improved electron emission properties with thermal and electrical aging. For the set-up of electrical aging, we used bias voltage at Joule heating appeared. Our CNT emitters show increases of electron emission at initial stage of aging and then saturation of emission current. With the electrical aging, we obtained enhanced electron emission from 3 mA to 5.5 mA and long- time stable operation.
关键词： Field emission,Carbon nanotubes,Electrical aging,Annealing
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Fluctuations of the emission characteristics of multi-tip field cathodes
摘要： Report presents a complex experimental study of the fluctuations in the emission characteristics of multi-tip field cathodes based on composites "disordered carbon nanotubes in a polymer matrix". The objects of the study: correlation of the glow patterns of the field emission projector with the level of the macroscopic emission current, emission sites activity, distribution of the current load on the emission sites, field enhancement factor of the individual emission sites, dependence of the current-voltage characteristics and effective emission parameters on the voltage and vacuum levels, formation of a calibration grid on the SK-diagram, modeling of the adsorption/desorption processes on the emitter surface.
关键词： emitter surface analysis,field emission images,current fluctuation,nanocomposite,field emission,carbon nanotubes,IVC
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field emission patterns from carbon nanotubes calculated by time-dependent density functional theory
摘要： We calculated the field emission patterns of various types of carbon nanotubes (CNTs). Regarding the near field regime, emission patterns of CNTs and hydrogen terminated CNTs (H-CNTs) well corresponds to the atoms located in the tube tip. We also found different focusing features; a focused-type and an unfocused-type. The beams from armchair (5,5) and (6,6) types are focused, while the beam from zigzag (9,0) types are unfocused.
关键词： field emission,carbon nanotubes,emission pattern,time dependent density functional theory,first principle calculation,ab initio calculation
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - A Magnetic Focused CNT Travelling Wave Tube
摘要： A magnetic focused X-band travelling wave tube based on carbon nanotube cathode is presented. The travelling wave tube is operated in a uniform axial magnetic field. The extra magnetic field alleviates the electron beam focusing difficulty of electron gun and so allows it has a rather simple structure. The fabricated travelling wave tube is tested in a superconducting system and an electron beam transmittance of 86% is obtained.
关键词： Magnetic focused,Carbon nanotubes,Field emission cathodes,Travelling wave tubes
更新于2025-09-23 15:21:21