Carbon Nanotubes Research Articles

Co single atoms/nanoparticles over carbon nanotubes for synergistic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid

The preparation of high-value 2,5-furandicarboxylic acid (FDCA) from biomass-based platform compound 5-hydroxymethylfurfural (HMF) is an important synthetic reaction, as the resulting FDCA holds promise to replace terephthalic acid to produce environmentally friendly polyester materials. However, due to the complex tandem nature of the oxidation of HMF to FDCA, which involves several stable intermediates, efficient conversion of HMF and achieving a high FDCA yield remain challenging. Herein, a catalyst of Co SAs/NPs@N-CNTs comprising Co single atoms (Co SAs) alongside Co nanoparticles (Co NPs) supported on carbon nanotubes (CNTs) was synthesized. Co SAs/NPs@N-CNTs exhibited outstanding catalytic activity for the selective oxidation of HMF to FDCA, achieving 100% HMF conversion and 94.2% FDCA yield. This remarkable performance was attributed to the synergistic effect between Co SAs and Co NPs. Poisoning and acid treatment experiments indicated that Co SAs served as the active sites, while Co NPs did not directly act as active sites. Instead, Co NPs merely assisted the Co SAs on the sidelines, facilitating the efficient conversion of HMF into various intermediates and promoting the further conversion of these intermediates into FDCA, thereby achieving high FDCA productivity. This strategy offers new insights for designing efficient catalysts for complex tandem reactions.

Nanomaterials for Flexible Neuromorphics.

The quest to imbue machines with intelligence akin to that of humans, through the development of adaptable neuromorphic devices and the creation of artificial neural systems, has long stood as a pivotal goal in both scientific inquiry and industrial advancement. Recent advancements in flexible neuromorphic electronics primarily rely on nanomaterials and polymers owing to their inherent uniformity, superior mechanical and electrical capabilities, and versatile functionalities. However, this field is still in its nascent stage, necessitating continuous efforts in materials innovation and device/system design. Therefore, it is imperative to conduct an extensive and comprehensive analysis to summarize current progress. This review highlights the advancements and applications of flexible neuromorphics, involving inorganic nanomaterials (zero-/one-/two-dimensional, and heterostructure), carbon-based nanomaterials such as carbon nanotubes (CNTs) and graphene, and polymers. Additionally, a comprehensive comparison and summary of the structural compositions, design strategies, key performance, and significant applications of these devices are provided. Furthermore, the challenges and future directions pertaining to materials/devices/systems associated with flexible neuromorphics are also addressed. The aim of this review is to shed light on the rapidly growing field of flexible neuromorphics, attract experts from diverse disciplines (e.g., electronics, materials science, neurobiology), and foster further innovation for its accelerated development.

Electrochemical Sensing/Biosensing ‐ Bench to Market

The proposition of new sensors based on carbon (nano)structures as well as metal (nano)particles is a great alternative for electroanalysis. In this context, graphite, carbon nanotubes, graphene, carbon black and fullerene, as well as gold, silver, platinum, copper are the most common materials employed [1]. Also, biomolecules such as antibodies, DNA sequences, enzymes and aptamers can be promising molecular recognition elements and enable specific sensor/biosensor designs, with interferent species [2]. Since the pioneering works from Professor Joseph Wang [3,4], the screen‐printed and disposable electrodes have been reported in the literature as options to be used in point‐of‐care and point‐of use sites. Also, the evolution of 3D printing [5] and wearable devices have led to an increase in the number of papers reporting on their use.. The “Achilles heel” is that the laboratory creations don't make it to the market place [6]. Therefore, academia needs to think more about in the validation, demonstration and promotion of the laboratory developed technology with of new companies based on startups, for example, to attract investments and promote these sensors to commercial ones. In this context, the special issue “Electrochemical Sensing/Biosensing ‐ Bench to Market” brings the discussion and advances of electrochemical sensors, which can be used in many areas, such as medical, environmental, food safety, pharmaceutical, and forensic. For this purpose, the preparation, characterization, and application of these devices have attracted interest. Studies of the production, shelf‐life as well as reproducibility, and repeatability have been highlighted for mass production. Important subjects such as screen printing, and 3D printing are welcome for submissions. Therefore, we expect you to enjoy this Special Issue published in Electroanalysis.

Experimental Research on the Possibility of Changing the Adhesion of Epoxy Glue to Concrete

Among the many methods of joining different materials, gluing is characterized by its most specific nature. In comparison with, for example, welded, screwed, or overlapped connections, a glued connection depends on the largest number of factors. Many of them are related to the phenomenon of adhesion, which is complicated by definition. It has many shapes and forms, and its existence determines not only the durability of such a joint but also the possibility of its execution. Epoxy polymers are among the most commonly used adhesives. Their extremely good parameters can be easily modified by additives in the form of fillers. Compatibility between the filler and the adhesive allows for further improving the adhesive parameters in the glued joint. However, in order to effectively combine the adhesive and the filler, different, often specific mixing methods must be used. The following study presents the results obtained in an experimental research program, the aim of which was to increase the adhesion of epoxy resin to a properly prepared concrete substrate. As a method to increase the final adhesion, the addition of microsilica and carbon nanotubes in an experimentally determined amount was selected. The use of sonication as a mixing method together with cavitation allowed for improving the parameters which determine the final adhesion of the adhesive to concrete. The parameters which were selected to describe the course of changes in the adhesion of the adhesive to the concrete substrate were the viscosity, free surface energy, surface parameters, adhesion, and SEM images of the tested resin in various modification configurations. The obtained results make it possible to form stronger and more durable adhesive joints during the reinforcement of concrete structural elements using fiber-reinforced polymer (FRP) composites.

Exploring the Potential of Recycled Polyethylene Terephthalate—Lignocellulose/Carbon Nanotube–Graphene Nanosheets an Efficient Extractor for Oil Spill

The global challenge of oil spill treatment has been addressed using nanocomposite-based natural fibers. These materials offer great potential in oil spill cleanup and are considered due to their environmental friendliness, high efficiency, and low cost. Thus, the current study reports a novel composite fabricated from date palm fiber (DPF) and recycled polyethylene terephthalate (rPET) with a proper combination of a mixture of carbon nanotubes (CNTs) and graphene nanosheets (GNSs) for oil removal. The established nanocomposite (DPF-rPET/CNT/GNS) was fabricated via physical mixing of various quantities (0.9, 0.8, and 0.7 g) of PET, along with varying loads of DPF at different proportions of CNT:GNS. The prepared nanocomposite (DPF-rPET/CNT/GNS) was fully characterized using scanning electron microscopy–energy dispersive X-ray (SEM-EDX) analysis, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis. In static experiments and under the optimal parameters of pH, sorbent doze, shaking time, and quantity of diesel oil), the established sorbent (DPF-rPET/CNT-GNS nanocomposite) displayed excellent adsorption capacity (98 mg/g). This study also expands the utility of the sorbent for the reusability of the oil adsorption, maintaining performance after five cycles. The adsorption data fitted well with the Langmuir isotherm model with a correlation coefficient (R2) of 0.99 and maximum adsorption capacity of 99.7 mg/g, indicating monolayer adsorption. Additionally, the adsorption kinetics followed a pseudo-second-order model, with an R2 near unity and an adsorption capacity of 99.09 mg/g. This study highlights the promising potential of the DPF-rPET/CNT-GNS composite as an effective adsorbent for treating oily water.

Ce-doped NiFe-layered-double-hydroxide hierarchical nanocomposite and metal/imidazolate framework carbon nanotube nanocomposite: A bifunctional material for OER electrocatalyst and supercapacitor electrode applications

The development of nanocomposites as electrocatalysts with low cost and high efficiency for OER and as electrode material enhancing the electrochemical performance of supercapacitors are the most popular investigations in this field. Herein, a new bifunctional composite including Ce-doped NiFe-LDH Nanosheets and ZIF-derived carbon base incorporating neodymium and Fe into the structure of Zeolitic Imidazolate Framework is proposed and the construction was through entering Fe-ZIF8@Nd-ZIF67 into the structure of NiFeCe-LDH in different ratios of 10, 20 and 30 %. Various physical and electrochemical tests were conducted to evaluate the nanocomposites. Results indicated that the composite presented a hierarchical porous structure and exhibited outstanding performance for OER and supercapacitor applications. According to the results, the 30 % composite of NiFeCe-LDH/ Fe-ZIF8@Nd-ZIF67 exhibits a superior onset overpotential of 170 mV and an overpotential of 300 mV at a current density of 10 mA·cm−2. Besides, it shows an excellent specific capacitance of 345.36 (F.g−1) at 1 A.g−1. Hence, the synthesized nanocomposite demonstrated outstanding performance in both OER and supercapacitor applications.

Utility of Gold/Multiwalled Carbon Nanocomposite for Electrochemical Determination of Omarigliptin in Tablets and Human Plasma

Abstract An innovative voltammetric sensor was developed to estimate omarigliptin, a novel long-acting anti-diabetic drug. The sensor utilized a carbon paste electrode enhanced with a nanocomposite of carbon nanotubes and electrodeposited gold nanoparticles. The modified electrode was characterized using scanning electron microscopy and electrochemical impedance spectroscopy. The modification significantly improved the electrode's sensitivity and electrochemical efficiency and decreased its electron transfer resistance. The surface area of the modified electrode increased by about 2.8-fold compared to the bare electrode. Omarigliptin's oxidation behavior on the modified electrode was pH-dependent and irreversible, resulting in a peak current 4 times higher than the unmodified electrode. The modified electrode revealed good reproducibility, reusability, and stability. It allows for sensitive voltammetric analysis of omarigliptin over a linear range of 0.4–27 µM (LOD=0.12 µM) and good applicability in tablets and plasma. The recovery percentages are 98.47–101.27% in tablets and 95.86–105.02% in plasma. The modified electrode exhibits good selectivity towards OMR without interference from tablet excipients, endogenous plasma components, and co-administered drugs. The comparison with the reported methods reveals the superiority of the proposed method in terms of sensitivity, selectivity, applicability, and eco-friendliness. Finally, the proposed method demonstrates excellent environmental profiles based on recent assessment metrics.

Chemi-Impeditive Sensing Platform Based on Single-Walled Carbon Nanotubes.

Chemical sensing methodology based on electrochemical impedance spectroscopy (EIS) targeting analytes in aqueous samples on functionalized single-walled carbon nanotube (SWCNT) is reported. The SWCNT in contact with electrolyte shows unique impedance spectra that cannot be analyzed with classical equivalent circuit models. Inspired by the charge transport property of mixed ionic-electronic conductors, we propose an equivalent circuit based on transmission line model (TLM), by which the impedance of the CNT-electrolyte system can be analyzed to track down all the equivalent circuit parameters. By combining multiple pieces of information, which are technically immeasurable with conventional chemiresistive or chemicapacitive techniques, several analyte species responding to the sensor can be differentiated from each other. We demonstrate the "chemi-impeditive" concept on chemically modified SWCNTs for detecting perfluoroalkyl substances (PFAS) in aqueous solutions. The EIS coupled with a fluorination chemistry on SWCNT surface provides unique changes in equivalent circuit components for each PFAS, i.e., changes in CNT and solution resistances, as well as interfacial CNT-solution capacitance, through which perfluorooctanesulfonic acid, perfluorooctanoic acid, hexafluoropropylene oxide dimer acid, and perfluorobutanesulfonic acid are detected in a discriminative manner. The new impedimetric method opens up new vistas in chemical sensing in that the EIS analysis provides an additional dimension of information beyond the single resistance or capacitance typically measured by many conventional types of sensors.

Thermo-electric Characterization of Hydroxyapatite/ Multi-walled Carbon Nanotube Reinforced Polyetheretherketone Polymer Composites

Thermo-electric Characterization of Hydroxyapatite/ Multi-walled Carbon Nanotube Reinforced Polyetheretherketone Polymer Composites

Sonochemical Synthesis of Potassium-Intercalated Carbon Allotropes: Bulk Formation at Ambient Room Temperature.

Intercalation can be used to alter the electronic properties of graphitic materials. Intercalation is, however, a notoriously brute-force process typically carried out at a high temperature in an inert environment for an extended period. As an exception to this, a simple sonication-assisted intercalation of potassium into graphite at ambient room temperature (RT) has been reported. Here we extend this approach to intercalation of potassium into other carbon allotropes, including planar graphene nanoplatelets (GNPs) and curved graphitic tubes and shells, such as multiwalled carbon nanotubes (MWCNTs) and nanodiamond-derived carbon nano-onions (NCNOs). We report the rapid room-temperature sonication-assisted potassium metal intercalation of GNPs, MWCNTs, and NCNOs. Powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and electron dispersive X-ray spectroscopy (EDS) were used to visualize the location of potassium in the intercalated products.

Effect of nickel catalyst thickness on growth of carbon nanotubes on glass nonwoven mat using thermal chemical vapor deposition method

This study aimed to explore how varying the thickness of nickel catalyst affects the synthesis of carbon nanotubes on glass mats using the thermal chemical vapor deposition (TCVD) method. Nickel served as the catalyst, with acetylene as the hydrocarbon source and argon as the carrier gas. Initially, different thicknesses of nickel catalyst were applied to the glass mat via plasma-enhanced chemical vapor deposition (PECVD). Subsequently, these samples underwent TCVD plasma treatment. Electrical resistance measurements were conducted, and scanning electron microscopy (SEM), Raman spectroscopy, and transmission electron microscopy (TEM) were employed to analyze the presence, surface morphology, and quality of the nanotubes. The research revealed that the thickness of the nickel catalyst significantly influences the nanotube synthesis process on glass mat substrates. An optimal thickness of nickel catalyst yielded a glass mat with an electrical resistance of 2 Ω per unit area post-TCVD treatment.

Adenosine-Derivative Functionalized Carbon Nanotubes Considered as Catalysts for Vanadium Flow Batteries

Adenosine-Derivative Functionalized Carbon Nanotubes Considered as Catalysts for Vanadium Flow Batteries

High‐Performance Alkaline Battery‐Supercapacitor Hybrid Based on Bimetallic Phosphide/Phosphate

AbstractTransition metal‐based materials explored for energy storage applications viz. batteries, supercapacitors and more recently battery‐supercapacitor hybrids (BSHs) abundantly involve Co‐based materials. However, the supply chain issues and low electronic conductivity force us to look for alternative options. In this regard, Co‐free binary metal phosphide/phosphate consisting of Ni and V metal (NiVP/Pi) microspheres as the positive electrode of BSH which shows a high specific capacity of 502 C g−1 (1004 F g−1) at 2 mV s−1 while retaining a high specific capacity of 214 C g−1 (428 F g−1) at 12 A g−1 is reported. The high electronic conductivity of binary metal phosphide in NiVP/Pi electrode and the rich electrochemical active sites due to Ni and V metal centres results in exciting performance. More interestingly, the hybrid device is successfully developed by employing NiVP/Pi as the positive electrode and carbon nanotubes (CNTs) as the negative electrode. The hybrid device (NiVP/Pi//CNT) is able to achieve a maximum energy density of 22.17 Wh kg−1 and a power density of 5 kW kg−1 with 91.7% capacitance retention after 7500 continuous galvanostatic charge–discharge cycles.

Optimizing Fe-N-C Electrocatalysts for PEMFCs: Influence of Constituents and Pyrolysis on Properties and Performance

Proton exchange membrane fuel cells (PEMFCs) are promising alternative technologies with applications in stationary power systems, vehicles, and portable electronics due to their low temperature operation, fast start-up, and environmental advantages. However, the high cost of platinum-based catalysts, in particular for the oxygen reduction reaction (ORR) of the cathode side, prevents their widespread incorporation. Fe-N-C electrocatalysts have emerged as viable alternatives to platinum. In this study, different precursor components were investigated for the way that they affect the pyrolysis process, which is crucial for tailoring the final catalyst properties. In particular, carbon allotropes such as carbon Vulcan, Ketjenblack, and carbon nanotubes were selected for their unique structures and properties. In addition, various sources of iron (FeCl2, FeCl3, and K[Fe(SCN)4]) were evaluated. The influence of the pyrolysis atmosphere on the resulting Fe-N-C catalyst structures was also assessed. Through an integrated structure and surface chemistry analyses, as well as electrochemical tests with rotating disk electrode experiments in acidic media, the ORR performance and stability of these catalysts were defined. By examining the relationships between carbon sources and iron precursors, this research provides valuable information for the optimization of Fe-N-C catalysts in fuel cell applications.

Mechanical and Tribological Properties of Carbon Fiber Reinforced POM Composite Filled With Maleamidic Acid Treated Carbon Nanotube

ABSTRACTIn order to attain improved mechanical properties of the carbon fiber (CF) reinforced polyoxymethylene (POM) composite, maleamidic acid treated carbon nanotube (CNT) was deposited on carbon fiber. The mechanical properties of composites have been investigated. The tensile strength values of the treated CF/POM composites at all CNT mixing ratios are found to be higher than that of untreated one. The surface morphologies of the fractured surfaces of the composites were recorded using scanning electron microscopy (SEM) to gain information about the fiber–matrix interfacial adhesion in the composites. The friction coefficient of all the CF/POM/CNT composites decrease as the load increases from 10 to 20 N under the same sliding speed of 1000 r/min. XPS results showed that the formation of C–O, C=O, and O–C=O based species give rise to chemical bonds of the CF and the POM.

Suppression of Pt Nanocluster Aggregation and Enhanced Oxygen Reduction Activity by Heteroatom Doping of Carbon Nanotubes

Suppression of Pt Nanocluster Aggregation and Enhanced Oxygen Reduction Activity by Heteroatom Doping of Carbon Nanotubes

Differentiation of adsorption and degradation in steroid hormone micropollutants removal using electrochemical carbon nanotube membrane

The growing concern over micropollutants in aquatic ecosystems motivates the development of electrochemical membrane reactors (EMRs) as a sustainable water treatment solution. Nevertheless, the intricate interplay among adsorption/desorption, electrochemical reactions, and byproduct formation within EMR complicates the understanding of their mechanisms. Herein, the degradation of micropollutants using an EMR equipped with carbon nanotube membrane are investigated, employing isotope-labeled steroid hormone micropollutant. The integration of high-performance liquid chromatography with a flow scintillator analyzer and liquid scintillation counting techniques allows to differentiate hormone removal by concurrent adsorption and degradation. Pre-adsorption of hormone is found not to limit its subsequent degradation, attributed to the rapid adsorption kinetics and effective mass transfer of EMR. This analytical approach facilitates determining the limiting factors affecting the hormone degradation under variable conditions. Increasing the voltage from 0.6 to 1.2 V causes the degradation dynamics to transition from being controlled by electron transfer rates to an adsorption-rate-limited regime. These findings unravels some underlying mechanisms of EMR, providing valuable insights for designing electrochemical strategies for micropollutant control.

Energy-efficient design and CNFET implementation of GDI-based ternary prefix adders

Abstract Ternary adders have produced more benefits compared to binary adders i.e., the ternary adder occupies less amount of area as well as produces less interconnect complexity. However, the CMOS implementation of the ternary adders failed to perform the process when the channel length was taken as 32 nm. At 32 nm technology, the CMOS transistors exhibit undesired effects such as Short Channel Effects (SCEs), mobility degradation, high leakage current, etc. Multi-gate devices are preferred to overcome these issues. Carbon Nano-tube Field Effect Transistors (CNFETs) are one of the technologies to work efficiently when the channel length is 32 nm. In this paper, CNFET-based ternary prefix adders are designed. Power consumption is the most critical requirement for the VLSI system, as it enhances energy efficiency and reduces heat dissipation. One way to achieve this power reduction is by minimizing the number of transistors employed in the adder circuits. This study employed a reduction technique known as Gate Diffusion Input (GDI) logic included in the proposed prefix adder design. The overall experimental investigation is done with the help of the HSPICE supporting platform. The proposed adder improved by reducing the power by up to 83%, energy by up to 83%, current by up to 78%, and delay by up to 96%. Finally, the Power Delay product (PDP) was also reduced by 84% compared to existing ternary adders. The proposed design proves to be highly effective in implementing the neuron structure, with the corresponding parameters thoroughly analysed and well-documented in this study.

Dispersion and Stability Behaviour of Graphene and MWCNT Based Nano-Lubricant for Vapour Compression Refrigeration (VCR) System

Incorporating nanoparticles into oil compressors marks a significant advancement in scientific research. It has been widely demonstrated that the inclusion of nanoparticles can markedly improve the system's efficiency by reducing energy consumption, decreasing evaporator temperatures, and increasing condenser temperatures. Nanoparticles made of carbon, including those of metal, metal oxide, and metal hybrids, are particularly valued for their superior properties and are deemed to have considerable potential for achievements. This study focuses on examining the stability of graphene and multi-walled carbon nanotubes (MWCNT) in polyolester (POE) oil as a precursor to replacing conventional lubricating oil in refrigeration systems separately. Graphene nano-lubricants were tested at concentrations ranging from 0.1 to 0.3 g/L with the selected surfactant, cetyltrimethylammonium bromide (CTAB), in a 1:1 ratio, while MWCNT nano-lubricants were tested from 0.5 to 0.7 g/L. All samples were prepared using a two-step method that involved magnetic stirring at 1250 rpm for 45 minutes, followed by ultrasonication for 30 minutes. The samples underwent evaluation through three methods of observation. Initial visual observation was conducted immediately after production, then after a 24-hour settling period, and finally, after seven days, the three most optimal samples were identified. For MWCNT, an additional stability test was necessitated due to the high concentration levels, making it challenging to determine the three most stable concentrations. The UV-VIS spectrophotometer played a crucial role in analyzing the stability of the samples, providing data that enabled more precise results. The absorption peak at a wavelength of 294 nm reached its highest absorption value of 0.892 (a.u.) at a concentration of 0.2 g/L. In the case of MWCNT, after testing all samples, concentrations of 0.5, 0.55, and 0.65 g/L were identified as the best options based on peak absorption at different wavelengths, with their peaks at 4.87, 4.045, and 4.116 (a.u.), respectively. The Zeta Potential Analyzer confirmed the stability of these concentrations, indicating a moderate stability with values around -37.4 mV. This level of stability was also observed in MWCNT samples, with the three chosen concentrations showing excellent stability at 88.4, -84.9, and -137 mV, respectively. Among all tested nano-lubricant samples, those with concentrations of 0.2 g/L and 0.65 g/L for Graphene/CTAB/POE and MWCNT/POE, respectively, demonstrated the highest stability and optimum performance. This suggests that these concentrations have the potential to serve as replacements for POE oil in refrigeration systems.

Flexural and vibration behaviour of co-cured CFRP composite joints with MWCNT-modified adhesive

Among the diverse adhesive-bonded joining methods, the co-curing technique offers several advantages for fusing structural components. Co-curing technique effectively enhances specific strengths and ensures more equitable stress distribution. This research investigated the multi-walled carbon nanotubes (MWCNTs) incorporated with varying wt.% in carbon fibre-reinforced polymeric (CFRP) composite joints through co-cure bonding techniques. The effects of flexural and vibration behaviour in CFRP composite joints were evaluated using the three-point bending and free vibration tests. Experimental results revealed that the epoxy adhesive containing 0.5 wt.% nanofiller demonstrated the highest flexural strength and modulus. These values were significantly superior to pure epoxy adhesive, exhibiting increases of 270 and 120%, respectively. However, the 1.0 wt.% of nanofiller exhibited the maximum natural frequency under three vibration modes, which is 29, 17, and 14% higher than the pure epoxy adhesive. The statistical analysis of the results was examined using an ANOVA, ensuring the reliability of the findings. Optimisation and prediction were done with the Levenberg-Marquardt artificial neural network, further reinforcing the confidence in the outcomes. The overall coefficient (R) mean square error of 0.99844 is within the acceptable range, indicating that both outcomes are reliable and in agreement.