Facile fabrication of polystyrene particles/graphene composites for improved dielectric and thermal properties

From waste to energy storage: post-consumer waste expanded polystyrene/rGO composite as a high performance self-standing electrode for coin cell supercapacitors

This research work aims to explore the potential usage of post-consumer waste expanded polystyrene (EPS) for the fabrication of self-standing electrodes by incorporating reduced graphene oxide (rGO) into it via a facile cost-effective mechanical mixing process. The π-π interaction between the expanded polystyrene and rGO is evidenced from FT-IR and Raman analysis. The elevated thermal stability of the EPS/rGO composite from thermogravimetric analysis (TGA) further confirms the interconnection between the rGO and EPS. This π-π stacking interaction between the rGO and the polystyrene molecules present in the polymer matrix enable the composite material to be interconnected throughout which is beneficial for the charge transport process. The symmetric coin cell supercapacitor fabricated using the EPS/rGO composite electrode can be operated with a high operating voltage of 1.6 V in aqueous KOH and Na2SO4 electrolytes. The devices fabricated with KOH and Na2SO4 electrolytes deliver an areal capacitance of 11.9 mF cm-2 and 10 mF cm-2 at the discharge current density of 0.1 mA cm-2. Further, the devices fabricated with the KOH and Na2SO4 electrolytes demonstrated remarkable rate capability of 87.1% and 99.5% after 10 000 continuous charge discharge cycles. This facile method of preparation without consuming energy or polluting the environment is a novel approach which can be scaled-up to large-scale fabrication of self-standing plastic electrodes for low-cost energy storage applications.

Physical mechanism on the linear spectrum and nonlinear spectrum in a twist bilayer graphdiyne nanodisk

The one-photon absorption properties (OPA), two-photon absorption properties (TPA), electronic circular dichroism (ECD) spectra and partial DOS (PDOS) of a twist bilayer graphdiyne nanodisk (TwBLGDY-ND) were investigated by using a variety of quantum chemistry and wave function analyses. The physical mechanism of the twist bilayer graphdiyne nanodisk (TwBLGDY) with optical properties regulated by twisting angles was revealed. The results show that the twist angle makes the TwBLGDY form a moiré superlattice structure, and electron excitation mainly occurs in the first ring of the moiré superlattice structure. The contribution of atomic orbitals in these fragments to transition dipole moments is greater and electronic transitions are more likely to occur. When the twist angle increases from 0° to 15°, the absorption spectrum of the system is red shifted, which is mainly due to the enhancement of electron excitation characteristics. When the twist angle increases from 15° to 27.5°, the absorption spectrum of the system is blue shifted, due to the enhanced charge transfer within the layer. On the other hand, the twist angle can regulate the TPA absorption cross section of the system to enhance the intensity of the absorption spectrum. The twist angle can also regulate chirality by adjusting the spatial distribution of electric dipole transition and magnetic dipole transition. This study can provide theoretical guidance for constructing chiral optical devices based on the TwBLGDY structure.