Simple Method to Improve Electrical Conductivity of Films Made from Single-Walled Carbon Nanotubes

Porosity-Engineered CNT-MoS2 Hybrid Nanostructures for Bipolar Supercapacitor Applications

Bipolar supercapacitors that can store many fold higher capacitance in negative voltage compared to positive voltage are of great importance if they can be engineered for practical applications. The electrode material encompassing high surface area, better electrochemical stability, high conductivity, moderate distribution of pore size, and their interaction with suitable electrolytes is imperative to enable bipolar supercapacitor performance. Apropos of the aforementioned aspects, the intent of this work is to ascertain the effect of ionic properties of different electrolytes on the electrochemical properties and performance of a porous CNT-MoS₂ hybrid microstructure toward bipolar supercapacitor applications. The electrochemical assessment reveals that the CNT-MoS₂ hybrid electrode exhibited a two- to threefold higher areal capacitance value of 122.3 mF cm^-2 at 100 μA cm^-2 in 1 M aqueous Na₂SO₄ and 42.13 mF cm^-2 at 0.30 mA cm^-2 in PVA-Na₂SO₄ gel electrolyte in the negative potential window in comparison to the positive potential window. The CNT-MoS₂ hybrid demonstrates a splendid Coulombic efficiency of ∼102.5% and outstanding stability with capacitance retention showing a change from 100% to ∼180% over 7000 repeated charging-discharging cycles.

Doping of carbon nanotubes by halogenated solvents

Carbon nanotubes (CNTs) play a unique role in the area of flexible conductors as they have remarkably high electrical conductivity and bend easily without deformation. Consequently, CNTs are commonly deposited on substrates as conductive tracks/coatings. Halogenated solvents are often employed to facilitate the deposition process because they dry rapidly due to their high volatility. In this work, we report that halogenated solvents can dope CNTs considerably. The study showed that the use of dichloromethane, chloroform, or bromoform for the CNT deposition significantly impacts the chemical potential of the material, thereby modifying its charge transport characteristics. As a consequence, up to four-fold improvement in electrical conductivity is noted due to doping.

Bamboo Weaving Inspired Design of a Carbonaceous Electrode with Exceptionally High Volumetric Capacity

A highly densified electrode material is desirable to achieve large volumetric capacity. However, pores acting as ion transport channels are critical for high utilization of active material. Achieving a balance between high volume density and pore utilization remains a challenge particularly for hollow materials. Herein, capillary force is employed to convert hollow fibers to a bamboo-weaving-like flexible electrode (BWFE), in which the shrinkage of hollow space results in high compactness of the electrode. The volume of the electrode can be decreased by 96% without sacrificing the gravimetric capacity. Importantly, the conductivity of BWFE after thermal treatment can reach up to 50,500 S/m which exceeds that for most other carbon materials. Detailed mechanical analysis reveals that, due to the strong interaction between nanoribbons, Young's modulus of the electrode increases by 105 times. After SnO₂ active materials is impregnated, the BWFE/SnO₂ electrode exhibits an exceptionally ultrahigh volumetric capacity of 2000 mAh/cm³.

A Straightforward Approach to Create Ag/SWCNT Composites

Flexible and conductive materials have a high application potential across many parts of modern life. In this work, thin free-standing films from single-walled carbon nanotubes (SWCNTs) were doped with Ag to enhance their electrical conductivity. A facile method to integrate these two materials is described herein. As a consequence, the material exhibited a six-fold boost to the electrical conductivity: an increase from 250 ± 11 S/cm to 1721 ± 125 S/cm. Interestingly, the specific conductivity remained at a comparable level upon doping, so the material was deemed promising in exploitation fields whereweight is of the essence. Furthermore, the material showed good bending characteristics, thereby revealing its applicability in flexible electronics.

Effective Doping of Single-Walled Carbon Nanotubes with Polyethyleneimine

More and more electrically conducting materials are required to sustain the technological progress of civilization. Faced with the performance limits of classical materials, the R&D community has put efforts into developing nanomaterials, which can offer sufficiently high operational parameters. In this work, single-walled carbon nanotubes (SWCNTs) were doped with polyethyleneimine (PEI) to create such material. The results show that it is most fruitful to combine these components at the synthesis stage of an SWCNT network from their dispersion. In this case, the electrical conductivity of the material is boosted from 249 ± 21 S/cm to 1301 ± 56 S/cm straightforwardly and effectively.

Enhancing Electrical Conductivity of Composites of Single-Walled Carbon Nanotubes and Ethyl Cellulose with Water Vapor

Electrically conducting composites are highly sought-after materials. Their capacity to withstand mechanical deformation while simultaneously offering facile charge transport recently opened numerous exploitation fields for them. In this contribution, composites were made from single-walled carbon nanotubes (SWCNTs) and ethyl cellulose (EC). Then, a straightforward process of doping involving water vapor was developed and tested over 30 days. The inclusion of water in the EC/SWCNT network resulted in a notable increase in the electrical conductivity from 250 ± 21 S/cm to 905 ± 34 S/cm. Interestingly, doping of the material experienced remarkable stability due to the favorable surface chemistry of the EC filler.

Numerical Simulation of Darcy–Forchheimer 3D Unsteady Nanofluid Flow Comprising Carbon Nanotubes with Cattaneo–Christov Heat Flux and Velocity and Thermal Slip Conditions

A mathematical model comprising Darcy Forchheimer effects on the 3D nanofluid flow with engine oil as a base fluid containing suspended carbon nanotubes (CNTs) is envisioned. The CNTs are of both types i.e., multi-wall carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs). The flow is initiated by an exponentially stretched surface. The impacts of Cattaneo–Christov heat flux along with velocity and thermal slip conditions are key factors in the novelty of the defined model. The boundary layer notion is designed to convert the compact form of equations into the component shape. Appropriate transformations lead to differential equations with high nonlinearity. The final non-dimensional system is solved numerically by a “MATLAB” function known as bvp4c. For both CNTs, different graphical sketches are drawn to present the influence of arising parameters versus related profiles. The outcomes show that higher slip parameter boosts the axial velocity, whereas fluid temperature lowers for a sturdier relaxation parameter.