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- 2018
- Carbon nanotubes
- Magnetic focused
- Field emission cathodes
- Travelling wave tubes
- Heat Trap
- outgassing
- lifetime
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- Electronic Science and Technology
- Nanomaterials and Technology
- University of British Columbia
- Beijing Vacuum Electronics Research Institute
- Sun Yat-sen University
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Effect of temperature and bias voltage on electrical and electrochemical properties of diamond-like carbon films deposited with HiPIMS
摘要： The relatively high electrical resistivity of diamond-like carbon (DLC) film is one of the main drawbacks when applied in electronic device. In this study, DLC films were synthesized on 304 stainless steels by high power impulse magnetron sputtering (HiPIMS) process and the effect of deposition temperature and bias voltage on the microstructure, electrical and electrochemical properties, hardness and adhesion strength of the DLC films were investigated. The sp2/sp3 ratio of DLC films first decreased then increased and the surface became denser as bias voltage increasing from 0 to -400 V. While the film turned into graphite-like structure and became incompact when deposition temperature rose from 100 °C to 300 °C. The interfacial contact resistance (ICR) got reduced by increasing bias voltage and deposition temperature. However, as the deposition temperature increased to 300 °C the anticorrosion ability and hardness of DLC films deteriorated. The DLC films deposited at 300 °C presented soft and had better adhesion strength than hard DLC films deposited at 100 °C. DLC films deposited at -400 V bias and 300 °C had the lowest ICR while DLC films deposited at -400 V bias and 100 °C had the best performance when ICR, corrosion resistance and hardness were all taken into consideration.
关键词： Electrochemical corrosion,Substrate temperature,High power impulse magnetron sputtering,Interfacial conductivity,Diamond-like carbon,Bias voltages
更新于2025-09-23 15:22:29
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Photocatalytic and Filtration performance study of TiO2/CNTs-Filter for oil particle
摘要： Carbon nanotubes (CNTs) with large aspect ratio and specific surface area have the potential in oil liquid particle filtration and catalysis substrate field. In this work, we synthesized the TiO2/CNTs-filter for removing oil particle. Compared with the CNTs-filter, we found that the TiO2/CNTs-filter has smaller pore sizes, higher specific area. TiO2/CNTs-filter shows the excellent filtration performance which is higher than the high efficiency particulate air (HEPA) filter. In addition, the initial pressure drop of TiO2/CNTs-filter is close to conventional HEPA filter and the raise ratio of pressures drop at equilibrium states is less than conventional HEPA filter. Furthermore, the degradation rate of initial state and saturation state reach to 94.5 and 724 μg cm-2 h-1 in first 20 h respectively. At last, we simply discuss the application the composite filter on filtering cooking fume.
关键词： carbon nanotubes,filtration,composite filter,oil particle,photocatalytic
更新于2025-09-23 15:22:29
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Influence of gold nanolayer coating on the continuous-wave laser ablation of a pure aluminum surface: Evaluations of structural and optical features
摘要： In this paper, formation of uniform and large-area micro/nanostructures on pure aluminum surfaces using a continuous-wave laser irradiation is presented. Gold nanolayer coating was utilized as a confinement layer for controlling the possible hydrodynamic phenomena in a molten area. Dependency of the laser-induced morphology on the thickness of a gold coating was investigated in this regard. Scanning electron microscopy, energy dispersive spectroscopy, grazing test of the X-ray diffraction, and optical absorption/reflection spectroscopy in UV/visible/IR ranges were employed to characterize the samples. Results showed that the formation of uniform structures of average sizes of 50 nm-5μm on aluminum surface was possible following the irradiation of a continuous-wave CO2 laser, delivering 130 W beam power. Alterations of the surface morphology brought about an increase in specific absorption peaks at the UV region and the appearance of an absorption peak in the visible range. In addition, these structure-covered surfaces provided interesting reflection behaviors in different spectral areas, which can clearly reflect their high potential to be used as selective solar absorbers. The results of this investigation indicated that optical characteristics such as absorption and emission coefficients as well as ξ factor were 0.98, 0.13, and 7.53, respectively. It can therefore be concluded that this process can be considered an efficient and fast technique to fabricate selective solar absorbers.
关键词： Nanostructures,Aluminum,Selective solar absorber,Sputtering,Nanolayer,Continuous-wave CO2 laser,Gold,Black carbon
更新于2025-09-23 15:22:29
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Cobalt/Molybdenum Phosphides and Oxides Heterostructures Encapsulated in N-doped Carbon Nanocomposite for Overall Water Splitting in Alkaline Media
摘要： The development of designing and searching inexpensive electrocatalysts with highly activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is significant to enable water splitting as a future renewable energy source. Herein, we synthesis a new CoP(MoP)-CoMoO3 heterostructure coated by N-doped carbon shell (CoP(MoP)-CoMoO3@CN) via thermal decomposing and phosphatizing the CoMoO4?0.9H2O nanowires encapsulated in N-doped carbon. At 10 mA?cm?2, this CoP(MoP)-CoMoO3@CN nanocomposite exhibits superior electrocatalytic activity of low overpotentials of 296 mV for OER and 198 mV for HER in alkaline media. More importantly, we achieve a current density of 10 mA?cm?2 at 1.55 V by using this CoP(MoP)-CoMoO3@CN as both cathode and anode for overall water splitting. This promising performance could be due to the high activity of CoP(MoP)-CoMoO3 and the good conductivity of external mesoporous N-carbon shell, which makes the CoP(MoP)-CoMoO3@CN nanowires as a competitive alternative to noble metal based catalysts for water splitting.
关键词： metal phosphides,overall water splitting,synergistic effects,nanowires,N-doped Carbon
更新于2025-09-23 15:22:29
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Theranostic Carbon Dots with Innovative NIR-II Emission for in Vivo Renal Excreted Optical Imaging and Photothermal Therapy
摘要： Carbon dots (CDs) with low biotoxicity, high photostability, and well-controlled small size are highly desirable imaging agents for optical bioimaging. However, most of the CDs triggered by ultraviolet (UV)/blue light present visible/first near infrared (NIR-I) emissions shorter than 820 nm, impairing their imaging applications in vivo by low penetration depth. Hence, developing novel CDs based materials with second near infrared (NIR-II) emission located in 1000-1700 nm region is an urgent task. Here, a novel NIR-II emitting CDs-based nanoprobe triggered by 808 nm laser is developed. The designed CDs with 900-1200 nm luminescence possess high quantum yield (QY-0.4%), and high biocompatibility, which have proven to be effective probes for in vivo NIR-II bioimaging. Notably, nearly 65% CDs are excreted from mouse urine within 6 h, further demonstrating the rapid renal clearance of CDs. Furthermore, the designed CDs also exhibit high photothermal efficiency (30.6%), making them ideal materials for thermal ablation of cancer. Our findings pave the way of designing multifunctional CDs-based theranostic platform for simultaneously integrating the advanced NIR-II bioimaging and photothermal therapy (PTT) of cancer.
关键词： carbon dots,renal clearance,photothermal therapy of cancer,NIR-II bioimaging,NIR-triggered NIR-II emission
更新于2025-09-23 15:22:29
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Self-Floating Carbonized Tissue Membrane Derived from Commercial Facial Tissue for Highly Efficient Solar Steam Generation
摘要： Solar steam generation holds a great promise for practically utilizing solar energy in sea water desalination and sewage purification on a large scale. It has been proven that local heating of the superficial water can maximize the energy efficiency for steam generation. So the photothermal materials are required to float on water while working. However, the fabrication of a photothermal material with self-floating ability, low cost and easy-preparation for solar steam generation is highly challenged. Herein, self-floating carbonized tissue membrane for high efficiency solar steam generation is prepared via the carbonization of the commercial facial tissue. The low-cost and scalable carbonized tissue membrane can float on water without any assistance, and can effectively generate water steam at the rate of 4.45 kg m-2 h-1 with photothermal conversion efficiency of as high as 95 % under 3-sun illumination. The self-floating ability, high solar steam generation performance and low cost make the carbonized tissue membrane to be potential alternative for practical application in the future.
关键词： Self-floating,Membrane,One-step synthesis,Carbon material,Solar steam generation
更新于2025-09-23 15:22:29
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Controlling the fluorescence and room-temperature phosphorescence behaviour of carbon nanodots with inorganic crystalline nanocomposites
摘要： There is a significant drive to identify alternative materials that exhibit room temperature phosphorescence for technologies including bio-imaging, photodynamic therapy and organic light-emitting diodes. Ideally, these materials should be non-toxic and cheap, and it will be possible to control their photoluminescent properties. This was achieved here by embedding carbon nanodots within crystalline particles of alkaline earth carbonates, sulphates and oxalates. The resultant nanocomposites are luminescent and exhibit a bright, sub-second lifetime afterglow. Importantly, the excited state lifetimes, and steady-state and afterglow colours can all be systematically controlled by varying the cations and anions in the host inorganic phase, due to the influence of the cation size and material density on emissive and non-emissive electronic transitions. This simple strategy provides a flexible route for generating materials with specific, phosphorescent properties and is an exciting alternative to approaches relying on the synthesis of custom-made luminescent organic molecules.
关键词： room temperature phosphorescence,photoluminescence,heavy atom effect,carbon nanodots,nanocomposites
更新于2025-09-23 15:22:29
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Layer by layer deposition of alternate carbon nanotubes and Ni films for efficient multilayer thin film temperature gauges
摘要： This study reports a novel approach for growing multilayer thin films consisting of alternate layers of carbon nanotubes (CNT) and nickel on Si (1 0 0) substrates and justifies their use in thin film temperature sensors. A low pressure chemical vapor deposition system was employed for synthesizing CNT films, while Ni films were deposited by electrodeposition. Porous-Si was used as substrate to increase adhesion between the layers of the multilayer structure. The structure of the multilayer films and the quality of the CNT grown were analyzed using several characterization methods, including scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray auger electron spectroscopy and Raman spectroscopy. The electrical characteristics were investigated using a van der Pauw setup and the effect of the increasing number of CNT layers in the multilayer structure was studied. The sensitivity of the multilayer film was found to increase with increasing number of CNT layers, despite the decrease of the temperature coefficient of resistance. On the other hand, the initial resistance was found to increase. Results indicated that these multilayer structures are appropriate for fabricating highly sensitive thin film gauges that can detect lower heat fluxes with more accuracy.
关键词： carbon nanotubes,thin film gauges,surface and interface chemistry,porous silicon,adhesion sensing,x-ray photoelectron spectroscopy
更新于2025-09-23 15:22:29
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Impact paint sensor based on polymer/multi-dimension carbon nano isotopes composites
摘要： We presented a novel impact paint sensor made of piezoresistive nano-carbon composites and studied its characteristics. The paint sensors were fabricated with multi-walled carbon nanotube (MWCNT), exfoliated graphite nano-platelets (xGnP), and a hybrid type of the two nano-carbon fillers and were sprayed onto a carbon fiber reinforced plastic (CFRP) panel for lab testing. In ball drop impact test, the MWCNT-xGnP-based hybrid sensor showed the best characteristics in impact energy sensing within the range 0.07-1.0J. We also studied the piezoresistive mechanism due to dimensional variations of nano carbon isotopes for sensor design. Piezorestivity of nano-carbon sensor was significantly dominated the electrical contact variation of the electrical fillers in a matrix. This study is expected to provide a feasibility test for designing impact paint sensors with optimized sensitivity for a composite structural health monitoring (SHM).
关键词： Carbon nanotube (CNT),Exfoliated graphite nanoplate (xGnP),Structural health monitoring (SHM),Unmanned aerial vehicle (UAV),Impact paint sensor
更新于2025-09-23 15:22:29
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Direct observation of cross-polarized excitons in aligned single-chirality single-wall carbon nanotubes
摘要： Optical properties of single-wall carbon nanotubes (SWCNTs) for light polarized parallel to the nanotube axis have been studied extensively, whereas their response to light polarized perpendicular to the nanotube axis has not been well explored. Here, by using a macroscopic film of highly aligned single-chirality (6,5) SWCNTs, we performed a systematic polarization-dependent optical absorption spectroscopy study. In addition to the commonly observed angular-momentum-conserving interband absorption of parallel-polarized light, which generates E11 and E22 excitons, we observed a small but unambiguous absorption peak whose intensity is maximum for perpendicular-polarized light. We attribute this feature to the lowest-energy cross-polarized interband absorption processes that change the angular momentum along the nanotube axis by ±1, generating E12 and E21 excitons. Unlike previous observations of cross-polarized excitons in polarization-dependent photoluminescence and circular dichroism spectroscopy experiments, our direct observation using absorption spectroscopy allowed us to quantitatively analyze this resonance. Specifically, we determined the energy and oscillator strength of this resonance to be 1.54 and 0.05, respectively, compared with the values for the E11 exciton peak. These values, in combination with a comparison with theoretical calculations, in turn led to an assessment of the environmental effect on the strength of Coulomb interactions in this aligned single-chirality SWCNT film.
关键词： polarization-dependent,single-wall carbon nanotubes,cross-polarized excitons,aligned film,optical absorption spectroscopy,Coulomb interactions
更新于2025-09-23 15:22:29