Performance Improvement of Supercapacitor Materials with Crushed 3D Structured Graphene

Conventional 2D-graphene sheets (2D-rGO) often demonstrate poor performance as capacitor materials, especially in cyclability due to the lamellar stacking and agglomeration of the electrode materials. Herein, we have proposed that crushed 3D-graphene (c-3D-rGO) can overcome the limitation. A simplistic way to prepare 3D-crushed graphene structures has been presented utilizing metal rGO core-shell (Ni@rGO) followed by acid leaching. The electrochemical performances of the prepared c-3D-rGO were evaluated as capacitor material using a three-electrode system with aqueous 0.5 M Na2SO4 solution through cyclic voltammetry and galvanostatic charge-discharge measurements. 2D-rGO was separately prepared to compare the performance with 3D-crushed graphene structures. It has been observed that the calculated specific capacitance (Csp) value of the prepared c-3D-rGO was 335 Fg-1 at a current density of 0.15 Ag-1, which was about three times higher than that of the 2D-rGO. The c-3D-rGO electrode retained 100% capacitance of its initial value after 10000 cycles, demonstrating the material’s excellent electrochemical stability. Furthermore, to show the performance in hybrid capacitor, manganese oxide (MnOx) with c-3D-rGO. The presence of c-3D-rGO significantly improved the capacitive performance MnOx.

Closed Neighborhood Degree Sum-Based Topological Descriptors of Graphene Structures

Topological descriptors defined on chemical structures enable understanding the properties and activities of chemical molecules. In this paper, we compute closed neighborhood degree sum-based indices for four different Graphene structures. The cardinality of closed neighborhood degree-based edge partitions for four different Graphene structures is used to compute the closed neighborhood degree sum-based indices.

Disordered photonics behavior from terahertz to ultraviolet of a three-dimensional graphene network

The diffusion of light by random materials is a general phenomenon that appears in many different systems, spanning from colloidal suspension in liquid crystals to disordered metal sponges and paper composed of random fibers. Random scattering is also a key element behind mimicry of several animals, such as white beetles and chameleons. Here, random scattering is related to micro and nanosized spatial structures affecting a broad electromagnetic region. In this work, we have investigated how random scattering modulates the optical properties, from terahertz to ultraviolet light, of a novel functional material, i.e., a three-dimensional graphene (3D Graphene) network based on interconnected high-quality two-dimensional graphene layers. Here, random scattering generates a high-frequency pass-filter behavior. The optical properties of these graphene structures bridge the nanoworld into the macroscopic world, paving the way for their use in novel optoelectronic devices.

TRANSPORT CHARACTERISTICS NUMERICAL CALCULATION OF TWO-DIMENSIONAL NANOMATERIALS

In this work, the current-voltage characteristics of graphene structures with an superperiod are calculated by the transfer matrix numerical method.

Grand Canonical Monte Carlo Simulations to Determine the Optimal Interlayer Distance of a Graphene Slit-Shaped Pore for Adsorption of Methane, Hydrogen and their Equimolar Mixture

The adsorption—for separation, storage and transportation—of methane, hydrogen and their mixture is important for a sustainable energy consumption in present-day society. Graphene derivatives have proven to be very promising for such an application, yet for a good design a better understanding of the optimal pore size is needed. In this work, grand canonical Monte Carlo simulations, employing Improved Lennard–Jones potentials, are performed to determine the ideal interlayer distance for a slit-shaped graphene pore in a large pressure range. A detailed study of the adsorption behavior of methane, hydrogen and their equimolar mixture in different sizes of graphene pores is obtained through calculation of absolute and excess adsorption isotherms, isosteric heats and the selectivity. Moreover, a molecular picture is provided through z-density profiles at low and high pressure. It is found that an interlayer distance of about twice the van der Waals distance of the adsorbate is recommended to enhance the adsorbing ability. Furthermore, the graphene structures with slit-shaped pores were found to be very capable of adsorbing methane and separating methane from hydrogen in a mixture at reasonable working conditions (300 K and well below 15 atm).