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La-modified TiO2/carbon nanotubes assembly nanocomposite for efficient photocatalytic hydrogen evolution from glycerol-water mixture
摘要： Lanthanum (La) modified TiO2 embedded over carbon nanotubes (CNTs) to develop nanocomposite for enhanced photocatalytic hydrogen evolution from glycerol-water mixture has been investigated. The samples, synthesized by sol-gel assisted hydrothermal method, were characterized by XRD, FESEM, HRTEM, FTIR, BET, UVeVisible, Raman and PL spectroscopy. La/TiO2 anchored CNTs has larger surface area with uniform distribution of La3+ ions. The performance of hybrid assembly was evaluated in a continuous flow slurry photoreactor system under UVevisible light irradiations. The highest H2 evolution rate of 17265 ppm g-cat-1 h-1 was obtained over 5% La-5% CNTs/TiO2 NRs, 1.14 folds the amount produced over 5% La-5% CNTs/TiO2 NPs, 1.53 time than 5% La/TiO2 and 4.10 folds than using pure TiO2 NPs. This significant improvement in the photo-activity was obviously due to synergistic effect between La and CNTs, larger BET surface area, cleavage of glycerol by La, appropriate band structure, and hindered charges recombination rate. Among the sacrificial reagents, highest H2 evolution was obtained using glycerol due to the presence of a-hydrogen atoms attached to carbon atoms. A correlation between BET surface area and photonic flux in terms of photocatalytic H2 production rate was established to understand the performance of hybrid nanostructures. It was observed that BET surface area and photo-flux utilization for the generation of charge carriers with their efficient separation has significant contribution towards improved H2 production rate. More interestingly, catalyst persisted prolonged stability with a steady H2 production in cyclic runs. This study provides promising pathway for constructing composite of La/TiO2 coupled CNTs for efficient H2 production under visible light.
关键词： La/TiO2,Glycerol,TiO2/CNTs hybrid,H2 production,Visible light,Photo-catalysis
更新于2025-09-23 15:23:52
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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) - Study on Photoemission of Patterned Carbon Nanotubes Modified with Gold Nanoparticles
摘要： Employing the edge effect and localized surface plasmon resonance effect, an enhanced photoemission is obtained from a carbon nanotube (CNT) arrays modified with gold nanoparticles. Compared with the unpatterned CNTs, the quantum efficiency of patterned CNTs is improved from 3.69×10-6 to 1.85×10-5. After modification with gold nanoparticles, the quantum efficiency of patterned CNTs is further raised to 4.98×10-5. This work makes CNTs as a promising material for the high stability and high efficiency photocathode.
关键词： Patterning,Photocathode,Gold nanoparticles,CNTs
更新于2025-09-23 15:21:21
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Effect of energy band misalignment and morphology in In <sub/>2</sub> O <sub/>3</sub> -CNTs on electron transport in dye-sensitized solar cell
摘要： This study provides important insights in performance degradation of In2O3-MWCNTs (0.4 and 0.5 wt.%)-based dye-sensitized solar cell (DSSC) using chemical-bath deposition technique. In2O3-MWCNTs (0.4 wt.%) exhibited the highest power conversion efficiency of 0.312% with low electron recombination rate, keff of 1256.72 s?1, and faster electron lifetime, seff of 0.80 ms compared to In2O3-MWCNTs (0.5 wt.%). The energy band misalignment between the conduction band of In2O3 photoanode and FTO caused severe electron recombination in In2O3-MWCNTs (0.5 wt.%). Therefore, this study can be used as a benchmark of 0.4 wt.% as the optimum concentration of MWCNTs in In2O3 for DSSC.
关键词： electron transport,optical,dye-sensitized solar cells,Chemical-bath deposition,In2O3-CNTs
更新于2025-09-23 15:21:01
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A Bean-Like Formation of Germanium Nanoparticles Inside CNTs by the Subsequent Operation of Colloidal Synthesis and Catalytic Chemical Vapor Deposition Methods
摘要： The first attempts of implanting Ge nanoparticles (Ge NPs) inside iron filled CNTs (IF-CNTs) by a subsequent use of the bench top colloidal synthesis and chemical vapor deposition (CVD) approach is shown. Ge NPs are colloidally synthesized (with a 3.8 ± 0.6 nm in size) before the deposition. The hybrid Ge NPs/IF-CNTs structure and morphology are characterized using high-resolution transmission electron microscopy, scanning electron microscopy, selective area electron diffraction, and X-ray diffraction studies. After the deposition, Ge NPs appear to be grown in size and to be sprinkled almost homogeneously into the IF-CNTs similar to a bean-like deposition. CNTs diameter is also identified to be enlarged drastically when using Ge NPs as a catalyst in CVD compared to the CNTs formation without Ge NPs. In addition, micro-length rectangular Ge μPs are also found outside the nanotube core. Rietveld analysis shows the presence of γ-Fe (Fm-3m), ferromagnetic α-Fe (Im-3m), Fe3C, Ge (Fd-3m), and multiwall CNTs. The results indicate that Ge NPs and IF-CNTs demonstrate cocatalytic activity in increasing the respective sizes, which are dramatically larger than those obtained by the conventional approaches.
关键词： ferromagnetism,germanium,nanoparticles,colloidal,chemical vapor deposition,CNTs
更新于2025-09-23 15:21:01
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Preparation and characterization of carbon nanotubes by pulsed laser ablation in water for optoelectronic application
摘要： In the present work, preparation of multi-walled carbon nanotubes (MWCNTs) and carbon nanoparticles (CNPs) by using pulsed laser ablation of a graphite target in water without using catalyst was demonstrated. The effect of laser wavelength on the optical absorption and structural properties has been studied. X-ray diffraction (XRD) data shows the synthesized CNTs were polycrystalline and a peak related to the diamond structure was observed. Scanning electron microscope (SEM) investigation displays that the average diameter of CNTs synthesized with 532 nm was 20 nm and few micrometers in length, while the CNTs synthesized with 1064 nm have an average diameter of 75 nm and lengths of few sub-micrometers. Some of CNPs were noticed to deposit on the CNTs. Transmission electron microscope (TEM) was used to study the morphology of MWCNTs. Raman spectra confirm formation of MWCNTs during the presence of three peaks belonged to D-band, G-band and 2D-band. The intensity ratio of IG/ID is larger than unity for MWCTs prepared by two laser wavelengths. The colloidal MWCNTs prepared by 532 nm laser pulses showed higher absorption than that of MWCNTs prepared with 1064 nm. The current-voltage characteristics and responsivity of hybrid In/p-MWCNTs/n-Si heterojunction photodetectors prepared at different CNTs film thicknesses were investigated at room temperature. The responsivity of hybrid MWCNTs/n-Si photodetector has two peaks of response, the first peak was found at 650 nm and the second peak located at 850 nm. The maximum responsivity was 0.53 A/W at 532 nm was found for the photodetector fabricated with 532 nm laser. The energy band diagram of MWCNTs/Si heterojunction was constructed under illumination condition.
关键词： Hybrid photodetector,CNTs,Laser ablation,CNTs thickness,Laser wavelength
更新于2025-09-23 15:19:57
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Thermal expansion behavior of CNT reinforced AlSi10Mg composite fabricated via laser powder bed fusion
摘要： Carbon nanotube (CNT) reinforced Al matrix composite exhibit good dimensional stability and can be a promising material with low coef?cient of thermal expansion (CTE). The thermal expansion behavior of CNT/AlSi10Mg composite with the CNTs content from 0 wt% to 2 wt% fabricated via laser powder bed fusion (LPBF) was investigated in this research. The CTE of all samples increased generally as the temperature increasing. At the same temperature, the CTE of the samples was smaller when CNTs content is lower. The best dimensional stability was reached as CNTs content was 2 wt%. The CTE deceased to 29.08 × 10?6 °C?1, as much as 16% reduction compared with unreinforced AlSi10Mg at 300 °C. The solid solution and precipitation behavior of Si in matrix and the interruptions of Si network resulted in the ?uctuation during dimension increase. With the CNTs distributed along the cell boundary, the Si network was consolidated. Hence, the microstructure of the composite became more stable and the CTE got lower with the addition of CNTs increasing. Moreover, the experimental results were similar to the predicted value of the thermoelastic model.
关键词： laser powder bed fusion,CNTs,coef?cient of thermal expansion,network
更新于2025-09-16 10:30:52
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Synthesis and Characterization of CNT Composites for Lasera??Generated Ultrasonic Waves
摘要： In the last few years, extensive progress in ultrasonic wave generation by using multiwalled carbon nanotubes (MWCNTs) in combination with polydimethylsiloxane (PDMS), functional composites, has been achieved. Due to high optical absorption of MWCNTs as perfect absorbers for laser beams and the high thermal expansion coefficient of PDMS, a compact transducer for ultrasonic wave generation at higher frequency can be realized. This study reports a novel method to synthesize MWCNT–PDMS composites deposited on a glass substrate by spray coating, which is done in a short time of 2 h. The layers (0.9–32.2 μm) show low optical transmission properties of 13.9–0.0% at a wavelength of 1047 nm. Apart from using a 1% Triton-X-100 stock solution and then diluted to a 0.1% relatively nonhazardous solution, no toxic chemicals are used. The Triton-X-100 solution is not hazardous for lab handling and is a commonly used lab detergent for the treatment of biological cells. The achieved sound pressure level is 3.4 MPa with a frequency bandwidth of 9.7 MHz. These results show the potential for a fast and nontoxic production of laser-generated ultrasonic transducers, which can be used well in the field of nondestructive material testing of layered materials or in medicine with an appropriate frequency range.
关键词： laser-generated ultrasonic waves,spray-coating methods,multi-walled CNTs,photophysics,nanocomposites,nanoparticles
更新于2025-09-16 10:30:52
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Realization of GaN-based gain-guided blue laser diodes by helium ion implantation
摘要： Na4MnV(PO4)3 (denoted as NMVP) has drawn increasing attention owing to the three-dimensional framework and high theoretical capacity. Nevertheless, the inherent low electronic conductivity of NMVP impedes the scale-up commercial applications. In this work, the feasibility to achieve ultrahigh-rate capability and long lifespan by in situ embedding the intertwined carbon nanotube (CNT) matrix into the bulk of Na4MnV-(PO4)3@C composites through a facile wet-chemical approach is reported. The elaborately prepared Na4MnV(PO4)3@C@CNTs cathode delivers a discharge capacity of 109.9 mA h g?1 at C/5 with an impressive rate capability of 68.9 mA h g?1 at an ultrahigh current rate of 90 C as well as a fascinating cycling performance of 68.3% capacity retention at 40 C after 4000 cycles. The optimum design of the 3D well-interconnected NMVP permitting fast kinetics for transported Na+/e? is bene?cial to the excellent electrochemical performance, which is further studied by the galvanostatic intermittent impedance spectra measurements. The pseudocapacitance contributions are also investigated. The research demonstrates that the dual-nanocarbon synergistically modi?ed NMVP composite is expected to facilitate the commercialization of sodium-ion batteries.
关键词： Na4MnV(PO4)3,sodium-ion batteries,ultrahigh-rate capability,long lifespan,CNTs
更新于2025-09-11 14:15:04