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- 2018
- Carbon nanotubes
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- University of British Columbia
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Resistive switching behavior and mechanism in flexible TiO2@Cf memristor crossbars
摘要： Fiber-based memristors are expected to be one of the most ideal candidates to the future wearable nonvolatile devices. In this work, Carbon fibers coated with rutile TiO2 nanorods (TiO2 NRs) were prepared via hydrothermal method, which were denoted as TiO2@Cf. Flexible TiO2@Cf memristor crossbar was facilely assembled on a polyimide (PI) film. This device exhibited bi-directional threshold switching behavior and a maximum ON/OFF ratio of 105. In addition, the conductance of the memristors can be continuously adjusted by consecutive sweep cycles of bias voltages. The devices also exhibit excellent endurance over 1500 cycles with a negligible shift. The carriers transport and resistance switching of the TiO2@Cf memristor crossbar were explained by the Fowler-Nordheim tunneling model. The oxygen vacancies (OV) in TiO2 drifted to the interface of TiO2/Cf by an applied electric field, thereby reducing the depletion region and enhancing the current. This work provides a profound understanding of the resistive switching behavior and the related mechanism in flexible TiO2@Cf memristor crossbars, and paves a new way for potential applications for memristors in artificial synapses and flexible devices.
关键词： Artificial synapses,Oxygen vacancies,Memristor crossbars,Flexible devices,Carbon fibers
更新于2025-11-14 17:03:37
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Carbon dots synthesized at room temperature for detection of tetracycline hydrochloride
摘要： The traditional synthesis methods of carbon dots (CDs) have some disadvantages of complicated operation and a large amount of energy consumption. To address these limitations, we synthesized yellow-green luminescent CDs at room temperature according to the principle of amine-aldehyde condensation in this work. This reaction is simple, economical, energy saving and is extremely consistent with the concept of green synthesis and sustainable development. In addition, studies have found that tetracycline hydrochloride (TC) can quench the fluorescence of the as-prepared CDs through Inner filter effect (IFE). The changes of the fluorescence intensity also have a good linear relationship with the concentration of TC in the range of 10.0-400.0 μM, and the detection limit is 6.0 μM. This method has been successfully used to determine the tetracycline content of tetracycline tablets. Finally, the interaction mechanism between TC and CDs was analyzed and discussed.
关键词： room temperature synthesis,tetracycline,carbon dots
更新于2025-11-14 17:03:37
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2,4,6-Trinitrophenol detection by a new portable sensing gadget using carbon dots as a fluorescent probe
摘要： An optical sensing gadget using fluorescence of carbon dots (CDs) was developed to realize the in-field detection of 2,4,6-trinitrophenol (TNP) in tap water and lake water samples. Fluorescent CDs were prepared through a one-step hydrothermal synthetic route. The fluorescence spectra demonstrated that the CDs could specifically discriminate TNP from other nitroaromatic explosives in an aqueous medium. The fluorescence of the CDs was quenched linearly with the concentration of TNP in the range from 1 to 100 μM, with a detection limit of 0.48 μM (3σ/k). The detection mechanism was ascribed to the synergistic effect of the inner filter effect and electron transfer. In addition, a portable sensing gadget based on a high-precision RGB color sensor and a micro control unit was developed. With use of the sensing gadget and the CDs, TNP detection in tap water and lake water samples was realized. Importantly, the portable sensing gadget combined with highly stable, low-toxicity, and sensitive CDs might have great potential for application in extensive in-field sensing situations.
关键词： 2,4,6-Trinitrophenol detection,Portable sensing gadget,Carbon dots,Fluorescence analysis
更新于2025-11-14 17:03:37
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A magnetofluorescent boron-doped carbon dots as a metal-free bimodal probe
摘要： High-resolution observation of biological process is vital for biological researches and diagnosing diseases, which requires accurate diagnosis that involves coordinating imaging technologies such as fluorescence and magnetic resonance (MR). Nowadays, metal-based labels have been used for dual modality imaging. However, heavy metal ions are not environment-and organism-friendly. Therefore, it is a desirable to fabricate a metal-free label with fluorescence and MR properties. Herein, we synthesized boron–doped carbon dots (B–CDs) with dual modal properties through a one-pot solvothermal process. Compared with boron-free CDs, B–CDs exhibited apparent red-shift, higher fluorescence intensity, and higher longitudinal relaxivity (r1 = 5.13 mM-1 s-1). It demonstrated that boron doping can enhance the fluorescence intensity of CDs, and maybe lead to form paramagnetic centers. The fluorescence and MR imaging of B–CDs make them a prospective label for clinical applications as a result of their oversimplified synthesis process, low cost, good biocompatibility and low toxicity. It will open a new window for building novel imaging labels.
关键词： Boron,Magnetic resonance,Fluorescence,Carbon dots
更新于2025-11-14 17:03:37
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Direct synthesis of ultrasmall and stable magnetite nanoparticles coated with one single carbon layer for sensitive surface-enhanced Raman scattering
摘要： Ultrasmall spherical magnetite nanoparticles (Fe3O4 NPs) coated with one single carbon layer (Fe3O4@1C NPs) were directly synthesized by a simple, fast one-step hydrothermal reaction at low temperature (200℃). The as-synthesized Fe3O4@1C NPs were easily separated and purified from the resultant mixture, without the need for any additional energy input and chemicals. The as-purified Fe3O4@1C NPs not only displayed typical superparamagnetic behavior but also exhibited quite good long-term stability after being exposed to the open air under the room conditions for more than 2 months. Importantly, the long-term stored Fe3O4@1C NPs exhibited a highly sensitive surface-enhanced Raman spectroscopy (SERS) response toward Rhodamine-b (RdB) molecules with low concentration. The multifunctional and recyclable Fe3O4@1C NPs presented a prospective application for the selective enrichment and sensitive SERS detection of chemical and biomolecular assays.
关键词： coated with one single carbon layer (Fe3O4@1C NPs),Dehydration reaction,Saturation magnetization,Long-term stability,Magnetite nanoparticles (Fe3O4 NPs)
更新于2025-11-14 17:03:37
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Determination of cholic acid in body fluids by β?cyclodextrin-modified N-doped carbon dot fluorescent probes
摘要： An easy, dependable, and sensitive cholic acid activity experiment was designed based on β?cyclodextrin-modi?ed carbon dot (β?CD-CD) nanoprobes with speci?c host–guest recognizing ability and photoelectron transfer capability. The β?CD-CD nanoprobes were characterized by infrared, ultraviolet-visible, and ?uorescence spectroscopy and transmission electron microscopy. The ?uorescence of the probes under optimized conditions linearly responded to cholic acid concentration from 0 to 650 μmol·L?1 with a detection limit of 25 nmol·L?1. The probes also performed well in detecting cholic acid in serum and urine samples with an average recovery rate of 97.1%–103.4%. Thus, this study provides a reliable, rapid, and easy method of cholic acid detection in body ?uids that can be potentially applied in medical studies.
关键词： Host–guest recognition,β?cyclodextrin,Cholic acid,Photoinduced electron transfer,Carbon dots
更新于2025-11-14 17:03:37
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Sensitive surface-enhanced Raman scattering detection of atrazine based on aggregation of silver nanoparticles modified carbon dots
摘要： The development of precise detection methods with simply operation for pesticides in various environmental samples is a particular challenge. Here a highly sensitive surface-enhanced Raman scattering (SERS) approach for the selective detection of trace atrazine was proposed with R6G as a Raman reporter, which was adsorbed on silver nanoparticles modified carbon dots. The latter were prepared by the reduction of Ag+ by carbon dots. In the presence of atrazine, the aggregation of the modified carbon dots due to the interaction between silver nanoparticles and atrazine led to great enhancement of the SERS signal of R6G. Under optimal assay conditions, the limit of quantification was estimated to be 10 nM, which matched with the standard for drinking water quality of China and WHO defined limit. A good linear response to atrazine was found in the concentration range of 10-1000 nM with the relative standard deviations between 1.8% and 5.6%. The determination of atrazine in real water samples was also carried out to confirm the practicability of the proposed method, which showed the recoveries from 95% to 117.5%. The target induced aggregation for enhancing the signal offered great potential for sensitive on-site detection of atrazine in environments.
关键词： Silver nanoparticles,Pesticides,SERS detection,Target induced aggregation,Atrazine,Carbon dots
更新于2025-11-14 17:03:37
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Acetylene black quantum dots as a bridge for few-layer g-C3N4/MoS2 nanosheet architecture: 0D–2D heterojunction as an efficient visible-light-driven photocatalyst
摘要： Great progress has been made based on photocatalytic theory research in the past few years. There is, however, still a long way to go to popularize the application of photocatalytic materials. Here, we introduce a simple synthetic 0D–2D (D: dimensional) heterogeneous material with more efficient photocatalytic degradation. We construct acetylene black (AB) as a bridge to connect a graphitic carbon nitride (g-C3N4) nano-layer and two-dimensional MoS2 sandwich structure based on a simple hydrothermal synthesis and ultrasonic chemical loading. Loading 1% AB onto 2D g-C3N4/(x%)MoS2 not only accelerates the transfer of charge, but also reduces electron–hole recombination, which increases the photocatalytic efficiency per unit time. Studies have shown that the degradation rate of the ternary g-C3N4/AB/3.1%MoS2 catalytic materials can reach 94.29%, which is obviously higher than that of the pure g-C3N4 (80%) or MoS2 (51.74%) in degradation of methyl blue within 130 min. In this work, the ternary heterogeneous catalyst realizes the complementary characteristics between materials, broadens the photocatalytic properties and accelerates the degradation rate of pollutants, and provides a feasible solution to environmental friendliness.
关键词： Graphitic carbon nitride,Ternary photocatalyst,Photocatalytic degradation,QDs/g-C3N4/MoS2
更新于2025-11-14 15:32:45
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Correlation of acetylene plasma discharge environment and the optical and electronic properties of the hydrogenated amorphous carbon films
摘要： Thin films from polymeric and graphitic hydrogenated amorphous carbon (a-C:H) were deposited over a glass substrate from acetylene (C2H2) plasma by using a conventional plasma enhanced chemical vapor deposition (PECVD). Radio frequency capacitively coupled plasma (RF CCP) source operating at a frequency of 13.56 MHz was used for generation of the discharge. Optical emission spectroscopy (OES) results showed strong optical emissions from diacetylene ion C4H2+ at a wavelength of 506 nm. The energy dispersive X-Ray (EDS) measurements illustrated that the carbon content in the deposited films increased with increasing of power. The Raman and IR results demonstrated that the films deposited at low bias voltages 340 V are so called polymeric a-C:H with high sp3 fraction and high hydrogen content, while the films deposited at high bias voltages 877 V are so called graphitic a-C:H with low sp3 fraction and low hydrogen content. Quantitative information were obtained from fitting the high asymmetrical vibrational modes of Raman and IR spectra by using Fano model expression together with Lorentzian function. The results presented here point out that there is a relation between the intensity of C4H2+ ion emissions and the deposited films properties.
关键词： Optical Emission,diacetylene ion,RF CCP,Hydrogenated amorphous carbon,FTIR,Raman spectroscopy
更新于2025-11-14 15:30:11
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Directed Nanoscale Self-assembly of Natural Photosystems on Nitrogen-doped Carbon Nanotubes for Solar Energy Harvesting
摘要： Natural photosystems (PSs) have received much attention as a biological solar energy harvester because of their high quantum efficiency for energy transfer. However, the PSs hybridized with solid electrodes exhibit low light-harvesting efficiencies because of poor interface properties and random orientations of PSs, all of which interfere with efficient charge extraction and transfer. Herein, we report the linker-free, oriented self-assembly of natural PSs with nitrogen-doped carbon nanotubes (NCNTs) via electrostatic interaction. Protonated nitrogen-doped sites on the NCNTs facilitate spontaneous immobilization of the negatively charged stroma side of PSs, which provides a favorable orientation for electron transfer without electrically insulating polymer linkers. The resulting PS/NCNT hybrids exhibit a photocurrent density of 1.25 ± 0.08 μA cm-2, which is much higher than that of PS/CNT hybrids stabilized with polyethylenimine (0.60 ± 0.01 μA cm-2) and sodium dodecyl sulfate (0.14 ± 0.01 μA cm-2), respectively. This work emphasizes the importance of the linker-free assembly of PSs into well-oriented hybrid structures to construct an efficient light-harvesting electrode.
关键词： Light-harvesting,Electrostatic interaction,Photosystems,Nitrogen-doped carbon nanotubes,Self-assembly
更新于2025-11-14 15:29:11