Finite element modelling of the mechanics of discrete carbon nanotubes filled with ZnS and comparison with experimental observations

The mechanical response to a uniaxial compressive force of a single carbon nanotube (CNT) filled (or partially-filled) with ZnS has been modelled. A semi-empirical approach based on the finite element method was used whereby modelling outcomes were closely matched to experimental observations. This is the first example of the use of the continuum approach to model the mechanical behaviour of discrete filled CNTs. In contrast to more computationally demanding methods such as density functional theory or molecular dynamics, our approach provides a viable and expedite alternative to model the mechanics of filled multi-walled CNTs

Influence of catalyst metal particles on the hydrogen sorption of single-walled carbon nanotube materials

The hydrogen sorption capacity of arc-synthesized single-walled carbon nanotubes (SWNTs) was studied using a specially built high-pressure rig coupled to a Toepler pump capable of directly measuring the desorbed volumes of gas. The samples studied were prepared using the arc-evaporation method and were as-produced SWNT material formed at the cathode (collar), as-produced SWNTs deposited in the soot and a purified sample of SWNTs. The three samples had similar diameter ranges, the major difference between them being the concentration of remaining metal particles from the Ni/Y/C catalyst used in the arc-synthesis. The effect of the presence of these residual catalyst metal particles has been analysed and seen to strongly influence the hydrogen storage capacity of the samples

3D Laser Scribed Graphene Derived from Carbon Nanospheres: An Ultrahigh-Power Electrode for Supercapacitors

Laser scribed graphene (LSG) electrodes hold great potential as supercapacitor electrodes. However, the rate performance of LSGs has been limited by the micropore-dominated electrode structure. Here, a new method is proposed to prepare LSG electrodes with a 3D porous framework dominated by meso- and macro-pores, a property that enables exceptional rate performance. The process uses amorphous carbon nanospheres (CNS) as precursors, which, after laser scribing, are transformed into highly turbostratic graphitic carbon electrodes (henceforth denoted as CNS-LSG) with a 3D framework structure dominated by meso- and macro-pores. When used as electrodes in conventional supercapacitor devices, the CNS-LSG electrodes exhibit a high volumetric power density of 28 W cm−3, which is 28 times higher than that of current commercial activated carbon supercapacitors, and is the highest among all the reported laser scribed/induced graphene electrodes

Lignin Laser Lithography: A Direct-Write Method for Fabricating 3D Graphene Electrodes for Microsupercapacitors

In this work, a simple lignin-based laser lithography technique is developed and used to fabricate on-chip microsupercapacitors (MSCs) using 3D graphene electrodes. Specifically, lignin films are transformed directly into 3D laser-scribed graphene (LSG) electrodes by a simple one-step CO2 laser irradiation. This step is followed by a water lift-off process to remove unexposed lignin, resulting in 3D graphene with the designed electrode patterns. The resulting LSG electrodes are hierarchically porous, electrically conductive (conductivity is up to 66.2 S cm−1), and have a high specific surface area (338.3 m2 g−1). These characteristics mean that such electrodes can be used directly as MSC electrodes without the need for binders and current collectors. The MSCs fabricated using lignin laser lithography exhibit good electrochemical performances, namely, high areal capacitance (25.1 mF cm−2), high volumetric energy density (≈1 mWh cm−3), and high volumetric power density (≈2 W cm−3). The versatility of lignin laser lithography opens up the opportunity in applications such as on-chip microsupercapacitors, sensors, and flexible electronics at large-scale production