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Progress in Dielectrophoretic Assembly of Carbon Nanotubes for Sensing Application
摘要： Carbon nanotubes (CNTs) have shown their potential for broad applications in field effect transistor, field emission, interconnects, energy storage, biomedicine, and many others, due to their excellent electrical, thermal, and mechanical properties. One requirement for many of these applications is to assemble CNTs into designated devices. As a promising nanomanipulation method, dielectrophoresis (DEP) has been widely applied to assemble CNTs in the fabrication of CNT-based nanodevices. This paper presents a brief review of the progress in CNT-based nanosensors and the application of DEP in device making. These sensors focus on the sensing of gases, temperature, bioparticles, light, pressure, stress, and strain.
关键词： sensor,assembly,dielectrophoresis,carbon nanotube,application
更新于2025-09-23 15:21:21
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Photocatalytic degradation of phenol wastewater over Z-scheme g-C3N4/CNT/BiVO4 heterostructure photocatalyst under solar light irradiation
摘要： A series of carbon nanotubes (CNT) modified g-C3N4/BiVO4 photocatalysts were synthesized via wet-impregnation method and evaluated via degradation of phenol under solar light irradiation. The physicochemical properties of the as-developed photocatalyst were characterized using FTIR, XRD, FESEM, XPS, SAP and DR-UV Vis. The formation of g-C3N4/CNT/BiVO4 photocatalysts resulted in remarkable enhancement in the performance in which almost six times higher degradation rate in comparison to the pristine g-C3N4 and obeyed the pseudo-first-order kinetics and Temkin adsorption model. Congruously, the synergistic interaction between 2 wt. % of CNT and 5 vol. % of H2O2 as an oxidizing agent was capable of removing 80.6 % of phenol within 120 minutes. The profound photodegradation performance monitored was attributed to the better crystallinity structure obtained as shown in XRD and XPS analysis. Furthermore, the intimate contact between the CNT, g-C3N4 and BiVO4 in the heterostructure sample as shown in FESEM micrograph images does help in allowing a smooth electron-hole pair separation and migration, resulting in more available ?OH and ?O2ˉ radicals for photocatalytic degradation activities. The possible Z-scheme reaction mechanism has been proposed and active species trapping experiments have been carried out to find the role of active radical species responsible for the phenol degradation. Additionally, the g-C3N4/CNT/BiVO4 photocatalysts retained excellent stability even after several cycles. Congruently, a mathematical representation for understanding the interaction between CNT loading and H2O2 for photodegradation of phenol using response surface methodology (RSM) was successfully generated.
关键词： phenol degradation,bismuth vanadate,carbon nanotube,wastewater,graphitic carbon nitride,photocatalyst
更新于2025-09-23 15:21:01
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Continuous Synthesis of Double-Walled Carbon Nanotubes with Water-Assisted Floating Catalyst Chemical Vapor Deposition
摘要： Double-walled carbon nanotubes (DWCNTs) were synthesized and continuously collected using a water-assisted ?oating catalyst chemical vapor deposition (FCCVD) method. Di?ering from the conventional water-assisted synthesis in which water vapor is one part of the carrier gas mixture, we included de-ionized water in the catalyst system, which achieved a more uniform and controlled distribution for e?cient DWCNT production. Using a water-assisted FCCVD process with optimized conditions, a transition from multi- to double-walled CNTs was observed with a decrease in diameters from 19–23 nm to 10–15 nm in tandem with an elevated Raman IG/ID ratio up to 10.23, and corroborated from the decomposition peak shifts in thermogravimetric data. To characterize the mechanical and electrical improvements, the FCCVD-CNT/bismaleimide (BMI) composites with di?erent water concentrations were manufactured, revealing high electrical conductivity of 1720 S/cm along the bundle alignment (collection) direction, and the nano-indentation tests showed an axial reduced modulus at 65 GPa. A consistent value of the anisotropic ratio at ~3 was observed comparing the longitudinal and transverse properties. The continuous capability of the presented method while maintaining high quality is expected to result in an improved DWCNT mass production process and potentially enhance the structural and electrical applications of CNT nanocomposites.
关键词： water-assisted FCCVD,anisotropic ratio,double-walled carbon nanotube (DWCNT) synthesis,electrical conductivity,nano-indentation
更新于2025-09-23 15:21:01
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Graphite/rolled graphene oxide/carbon nanotube photoelectrode for water splitting of exhaust car solution
摘要： Graphite/rolled graphene oxide/carbon nanotubes (G/R-GO/CNTs) was prepared and applied as a photoanode for water splitting from exhaust car solution. R-GO was prepared from graphene oxide (GO) using the modified Hummer method after settle down in solution for 2 months to roll out. The R-GO coated the graphite (G) electrode using the dip-coating method to form G/R-GO. Finally, CNTs were prepared on the G/R-GO electrode by using the chemical vapor deposition method to form G/R-GO/CNT electrode. The images of field emission scanning electron microscope show the formation of relatively homogenous and uniform R-GO with an average diameter of about 140 nm. Also, the high density of CNTs was observed with uniform diameters distribution and lengths of CNTs up to several micrometers. The values of the current density of the G/R-GO/CNT electrode for water splitting are changed from 0.82 mA cm?2 in dark to 1.50 mA cm?2 in light. The value of incident photon-to-current efficiency was 8.4% at 470 nm. The thermodynamic parameters were calculated, in which the activation energy (Ea), enthalpy (ΔH*), and entropy (ΔS*) values were 8.1 kJ mol?1, 29.9 J mol?1, and 56.4 J K?1 mol?1, respectively.
关键词： rolled graphene oxide,carbon nanotube,exhaust cars solution,H2 generation,water splitting
更新于2025-09-23 15:21:01
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Vibration Monitoring Based on Flexible Multi-walled Carbon Nanotube / Polydimethylsiloxane Film Sensor and the Application on Motion Signal Acquisition
摘要： Flexible sensors at small scales have potential applications in many fields. Until now, the research on high-performance vibration sensors based on soft materials with high sensitivity and precision, fast response, high stability are still in its infancy. In this work, a flexible, wearable and high precision film sensor based on multi-walled carbon nanotube (MWCNT) was prepared via a vacuum filtration process and then encapsulated within polydimethylsiloxane (PDMS). The sensor exhibits an ultrahigh sensitivity with gauge factor of 214.3 at flexural strain of 0.4 %. When used to monitor the vibration responses of a carbon-fiber beam induced by the base excitation and impact hammer, the time and frequency responses were comparable with the results obtained by the accelerometer, with difference less than 1 %. In addition, when the MWCNT/PDMS thin film was employed as an electronic skin sensor attached on the human body to detect human activities, the high sensitivity and repeatability demonstrate a great potential application in monitoring human motion.
关键词： human motion monitoring,vibration sensing,multi-walled carbon nanotube,film sensor
更新于2025-09-23 15:21:01
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Carbon Nanotubes - Recent Progress || Stability and Reliability of an Electrical Device Employing Highly Crystalline Single-Walled Carbon Nanotubes as a Field Emitter
摘要： Carbon nanomaterial is drawing keen interest from researchers as well as materials scientists. Carbon nanotubes (CNTs)—and their nanoscale needle shape—offering chemical stability, thermal conductivity, and mechanical strength exhibit unique properties as a quasi-one-dimensional material. Among the expected applications, field emission electron sources appear the most promising industrially and are approaching practical utilization. However, efforts to construct a field emission (FE) cathode with single-walled carbon nanotubes (SWCNTs) have so far only helped average out a non-homogeneous electron emitter plane with large FE current fluctuations and a short emission life-time because they failed to realize a stable emission current owing to crystal defects of the carbon network in CNTs. The utilization of CNTs to obtain an effective cathode, one with a stable emission and low FE current fluctuation, relies on the ability to disperse CNTs uniformly in liquid media. In particular, highly crystalline SWCNTs hold promise to obtain good stability and reliability. The author successfully manufactured highly crystalline SWCNTs-based FE lighting elements that exhibit stable electron emission, a long emission life-time, and low power consumption for electron emitters. This FE device employing highly crystalline SWCNTs has the potential for conserving energy through low power consumption in our habitats.
关键词： wet coating process,high crystallization,field emission,single-walled carbon nanotube,scratch,thin film,planar light source,cathode luminescence
更新于2025-09-23 15:21:01
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A Wearable UV Sensor Based on Carbon Nanotube Coated Cotton Thread
摘要： A fabric-compatible UV sensor is presented using a cellulose-based thread coated with single wall carbon nanotube ink. Two-terminal resistive responses of the thread were measured upon exposure to UV, and the effects of intensity, wavelength and on/off cycling were studied. The sensor was tested in the field under direct sunlight, demonstrating practical usability for a wearable/flexible UV sensor system. The results here confirm the potential for an inexpensive wearable sensor in contrast to the conventional rigid and bulky solid state detectors.
关键词： cellulose thread,wearable ultraviolet sensor,ultraviolet radiation,oxygen desorption-adsorption,single wall carbon nanotube
更新于2025-09-23 15:21:01
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Enhanced Ferroelectric Photovoltaic Effect in Semiconducting Single-Wall Carbon Nanotubes/BiFeO <sub/>3</sub> Heterostructure Enabled by Wide-Range Light Absorption and Efficient Charge Separation
摘要： The interfacial electronic band structures of photovoltaic heterostructure devices greatly affect their light absorption and charge-transport properties and thus their photovoltaic performance. In this work, we report an enhanced ferroelectric photovoltaic effect in a semiconducting single-walled carbon nanotube (S-SWCNTs)/ferroelectric BiFeO3 (BFO) heterostructure. A wide range of light absorption was possible in this structure owing to the low bandgaps of the S-SWCNTs (0.2–2.1 eV) and BFO (2.2–2.7 eV). The heterostructure also enabled efficient charge separation owing to the strong built-in electric field resulting from the synergic effect of the formation of p–f–n junctions (p-type S-SWCNTs/ferroelectric (f) BFO/n-type Nb:SrTiO3) and the introduction of a polarization-mediated internal field in the ferroelectric BFO layer. Compared with a single-layer device (Pt/BFO/Nb:SrTiO3), the heterostructure device (Pt/S-SWCNTs/BFO/Nb:SrTiO3) exhibited substantial enhancement of the photovoltaic performance. The open-circuit photovoltage and short-circuit photocurrent density reached up to 0.23 V and ?7.52 mA cm?2 (corresponding to a photo-conversion efficiency of 4.40%) under one-sun illumination, respectively, after optimization of the ferroelectric layer thickness and appropriate interfacial band alignment. Moreover, by applying switchable electric polarization, this heterostructure could be tuned, enabling the development of controllable photovoltaic devices. Our findings demonstrate that the synergistic integration of materials with different functionalities is a promising approach for the design of photovoltaic devices with tunable performance.
关键词： BiFeO3,light absorption,single-walled carbon nanotube,heterostructure,charge separation,ferroelectric photovoltaic effect
更新于2025-09-23 15:21:01
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Efficiency of Charge-Transfer Doping in Organic Semiconductors Probed with Quantitative Microwave and Direct-Current Conductance
摘要： Although molecular charge-transfer doping is widely used to manipulate carrier density in organic semiconductors, only a small fraction of charge carriers typically escape the Coulomb potential of dopant counterions to contribute to electrical conductivity. Here, we utilize microwave and direct-current (DC) measurements of electrical conductivity to demonstrate that a high percentage of charge carriers in redox-doped semiconducting single-walled carbon nanotube (s-SWCNT) networks is delocalized as a free carrier density in the π-electron system (estimated as >46% at high doping densities). The microwave and four-point probe conductivities of hole-doped s-SWCNT films quantitatively match over almost 4 orders of magnitude in conductance, indicating that both measurements are dominated by the same population of delocalized carriers. We address the relevance of this surprising one-to-one correspondence by discussing the degree to which local environmental parameters (e.g., tube?tube junctions, the relative Coulombic stabilization, and local bonding environment) may impact magnitudes of each transport measurement.
关键词： microwave conductivity,organic semiconductors,single-walled carbon nanotube,charge-transfer doping,DC conductivity
更新于2025-09-23 15:21:01
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Using Nonionic Surfactants for Production of Semiconductor-Type Carbon Nanotubes by Gel-Based Affinity Chromatography
摘要： Single-wall carbon nanotubes (SWCNTs) have remarkable properties based on their electronic properties, i.e., metallic or semiconducting types, but as-grown SWCNTs contain a mixture of both types. Presented here is an improved and detailed method for producing highly enriched semiconducting SWCNTs from a colloidal suspension of as-grown SWCNTs through agarose gel column-based affinity chromatography. After a 2 wt% sodium dodecyl sulphate (SDS) aqueous dispersion of SWCNTs is passed through the gel column, metal-type SWCNTs preferentially elute out using a 1.5 wt% SDS solution. Semiconductor-type SWCNTs are subsequently recovered from the column using a 2 wt% Pluronic F77 surfactant solution eluent. The semiconductor-enriched fraction purity is in the 90-95% range, based on detailed UV-vis-NIR absorption and resonant Raman spectroscopy characterization of the particulate suspension. Semiconductor-type SWCNTs are recovered in solid form by evaporating the suspension fluid, and heating the dried sample in air to a temperature just above the Pluronic decomposition temperature. Using Pluronic and other nonionic-type surfactants can aid the scalability of the chromatographic production of semiconducting SWCNT samples.
关键词： Carbon Nanotube,SWCNT,Semiconductor,Separation,Affinity Chromatography
更新于2025-09-23 15:21:01