The Effect of the Gaseous Environment on the Electrical Conductivity of Multi-Walled Carbon Nanotube Films over a Wide Temperature Range.

The surrounding gas atmosphere can have a significant influence on the electrical properties of multi-walled carbon nanotube (CNT) ensembles. In this study, we subjected CNT films to various gaseous environments or vacuum to observe how such factors alter the electrical resistance of networks at high temperatures. We showed that the removal of adsorbed water and other contaminants from the surface under reduced pressure significantly affects the electrical conductivity of the material. We also demonstrated that exposing the CNT films to the hydrogen atmosphere (as compared to a selection of gases of inert and oxidizing character) at elevated temperatures results in a notable reduction of electrical resistance. We believe that the observed sensitivity of the electrical properties of the CNT films to hydrogen or vacuum at elevated temperatures could be of practical importance

Copper-decorated CNTs as a possible electrode material in supercapacitors

Copper is probably one of the most important metal used in the broad range of electronic applications. It has been developed for many decades, and so it is very hard to make any further advances in its electrical and thermal performance by simply changing the manufacture to even more oxygen-free conditions. Carbon nanotubes (CNTs) due to their excellent electrical, thermal and mechanical properties seem like an ideal component to produce Cu-CNT composites of superior electrochemical performance. In this report we present whether Cu-CNT contact has a beneficial influence for manufacturing of a new type of carbon-based supercapacitor with embedded copper particles. The prepared electrode material was examined in symmetric cell configuration. The specific capacity and cyclability of composite were compared to parent CNT and oxidized CNT

The true amphipathic nature of graphene flakes: a versatile 2D stabilizer

The fundamental colloidal properties of pristine graphene flakes remain incompletely understood, with conflicting reports about their chemical character, hindering potential applications that could exploit the extraordinary electronic, thermal, and mechanical properties of graphene. Here, the true amphipathic nature of pristine graphene flakes is demonstrated through wet‐chemistry testing, optical microscopy, electron microscopy, and density functional theory, molecular dynamics, and Monte Carlo calculations, and it is shown how this fact paves the way for the formation of ultrastable water/oil emulsions. In contrast to commonly used graphene oxide flakes, pristine graphene flakes possess well‐defined hydrophobic and hydrophilic regions: the basal plane and edges, respectively, the interplay of which allows small flakes to be utilized as stabilizers with an amphipathic strength that depends on the edge‐to‐surface ratio. The interactions between flakes can be also controlled by varying the oil‐to‐water ratio. In addition, it is predicted that graphene flakes can be efficiently used as a new‐generation stabilizer that is active under high pressure, high temperature, and in saline solutions, greatly enhancing the efficiency and functionality of applications based on this materia

Comparative life cycle assessment of aluminium and CFRP composites: the case of aerospace manufacturing

As climate change intensifies and existing resources are depleted, the need for sustainable industries becomes more important. The aviation industry is actively addressing environmental concerns by enhancing fuel efficiency and adopting lighter materials, especially carbon fibre composites. Research has proven that the use of carbon fibre composites provides cumulative benefits in reducing fuel consumption over the entire life cycle of an aircraft. However, existing studies are lack of a comprehensive exploration of the diverse impacts associated with composite manufacturing processes and recycling methods. To address this gap, a comparative life cycle assessment analysis covering the materials’ manufacturing, operation, and end-of-life phases is conducted. This analysis includes aluminium alloy and five different carbon fibre composite materials produced with varied constituents and manufacturing methods. Composite manufacturing processes, encompassing carbon fibre production, resin selection, and composite manufacturing methods, are considered. Weight savings based on the mechanical properties of utilised composite type are also taken into account. Results highlight the potential to mitigate the environmental impact of composite materials through strategic choices in constituent types, manufacturing processes, and disposal scenarios. Moreover, break-even distances indicate that aluminium becomes more environmentally detrimental than the analysed composite structures beyond a flight distance of 300,000 km

The operational window of carbon nanotube electrical wires treated with strong acids and oxidants

Conventional metal wires suffer from a significant degradation or complete failure in their electrical performance, when subjected to harsh oxidizing environments, however wires constructed from Carbon Nanotubes (CNTs) have been found to actually improve in their electrical performance when subjected to these environments. These opposing reactions may provide new and interesting applications for CNT wires. Yet, before attempting to move to any real-world harsh environment applications, for the CNT wires, it is essential that this area of their operation be thoroughly examined. To investigate this, CNT wires were treated with multiple combinations of the strongest acids and halogens. The wires were then subjected to conductivity measurements, current carrying capacity tests, as well as Raman, microscopy and thermogravimetric analysis to enable the identification of both the limits of oxidative conductivity boosting and the onset of physical damage to the wires. These experiments have led to two main conclusions. Firstly, that CNT wires may operate effectively in harsh oxidizing environments where metal wires would easily fail and secondly, that the highest conductivity increase of the CNT wires can be achieved through a process of annealing, acetone and HCl purification followed by either H2O2 and HClO4 or Br2 treatment

Conductive inks of graphitic nanoparticles from a sustainable carbon feedstock

Microwave plasma splitting of biogas to solid carbon forms is a promising technique to produce large quantities of sustainable carbon based nano materials. Well defined graphitic nano carbons have been produced exhibiting graphene multilayers in turbostratic packing. After heat treatment, the purified material has been used to formulate stable, aqueous dispersions. These dispersions are used directly as inks, allowing the preparation of conductive membranes with remarkable resistivity. Nano carbons derived by plasma processes constitute a promising alternative to carbon black because they can be prepared from renewable sources of methane or natural gas, are calibrated in size, exhibit high conductivity, and have promising perspectives for chemical and material science purposes

Chitin and carbon nanotube composites as biocompatible scaffolds for neuron growth

Preparation of biocompatible and electrically-conducting chitin nanotube composite scaffold for potential use in implantable electrode for stimulation and repair of neurons.</p

Photonic Sorting of Aligned, Crystalline Carbon Nanotube Textiles

Floating catalyst chemical vapor deposition uniquely generates aligned carbon nanotube (CNT) textiles with individual CNT lengths magnitudes longer than competing processes, though hindered by impurities and intrinsic/extrinsic defects. We present a photonic-based post-process, particularly suited for these textiles, that selectively removes defective CNTs and other carbons not forming a threshold thermal pathway. In this method, a large diameter laser beam rasters across the surface of a partly aligned CNT textile in air, suspended from its ends. This results in brilliant, localized oxidation, where remaining material is an optically transparent film comprised of few-walled CNTs with profound and unique improvement in microstructure alignment and crystallinity. Raman spectroscopy shows substantial D peak suppression while preserving radial breathing modes. This increases the undoped, specific electrical conductivity at least an order of magnitude to beyond that of single-crystal graphite. Cryogenic conductivity measurements indicate intrinsic transport enhancement, opposed to simply removing nonconductive carbons/residual catalyst

Ionic liquids-based processing of electrically conducting chitin nanocomposite scaffolds for stem cell growth

In the present study, we have successfully combined the biocompatible properties of chitin with the high electrical conductivity of carbon nanotubes (CNTs) by mixing them using an imidazolium-based ionic liquid as a common solvent/dispersion medium. The resulting nanocomposites demonstrated uniform distribution of CNTs, as shown by scanning electron microscopy (SEM) and optical microscopy. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction confirmed the α-crystal structure of chitin in the regenerated chitin nanocomposite scaffolds. Increased CNT concentration in the chitin matrix resulted in higher conductivity of the scaffolds. Human mesenchymal stem cells adhered to, and proliferated on, chitin/CNT nanocomposites with different ratios. Cell growth in the first 3 days was similar on all composites at a range of (0.01 to 0.07) mass fraction of CNT. However, composites at 0.1 mass fraction of CNT showed reduced cell attachment. There was a significant increase in cell proliferation using 0.07 mass fraction CNT composites suggesting a stem cell enhancing function for CNTs at this concentration. In conclusion, ionic liquid allowed the uniform dispersion of CNTs and dissolution of chitin to create a biocompatible, electrically conducting scaffold permissive for mesenchymal stem cell function. This method will enable the fabrication of chitin- based advanced multifunctional biocompatible scaffolds where electrical conduction is critical for tissue function