Present state-of-the-art graphene-based electrodes for supercapacitors remain far from commercial requirements in terms of high energy density. The realization of high energy supercapacitor electrodes remains challenging, because graphene-based electrode materials are synthesized by the chemical modification of graphene. The modified graphene electrodes have lower electrical conductivity than ideal graphene, and limited electrochemically active surface areas due to restacking, which hinders the access of electrolyte ions, resulting in a low energy density. In order to solve the issue of restacking and low electrical conductivity, we introduce thiol-functionalized, nitrogen-doped, reduced graphene oxide scrolls as the electrode materials for an electric double-layer supercapacitor. The fabricated supercapacitor exhibits a very high energy/power density of 206 Wh/kg (59.74 Wh/L)/496 W/kg at a current density of 0.25 A/g, and a high power/energy density of 32 kW/kg (9.8 kW/L)/9.58 Wh/kg at a current density of 50 A/g; it also operates in a voltage range of 0~4 V with excellent cyclic stability of more than 20,000 cycles. By suitably combining the scroll-based electrode and electrolyte material, this study presents a strategy for electrode design for next-generation energy storage devices with high energy density without compromising the power density.

Graphene oxide (GO)-phosphor hybrid nanoscrolls were synthesized using a simple chemical method. The GO-phosphor ratio was varied to find the optimum ratio for enhanced optical characteristics of the hybrid. A scanning electron microscope analysis revealed that synthesized GO scrolls achieved a length of over 20 μm with interior cavities. The GO-phosphor hybrid is extensively analyzed using Raman spectroscopy, suggesting that various Raman combination modes are activated with the appearance of a low-frequency radial breathing-like mode (RBLM) of the type observed in carbon nanotubes. All of the synthesized GO-phosphor hybrids exhibit an intense luminescent emission around 540 nm along with a broad emission at approximately 400 nm, with the intensity ratio varying with the GO-phosphor ratio. The photoluminescence emissions were gauged using Commission Internationale d'Eclairage (CIE) coordinates and at an optimum ratio. The coordinates shift to the white region of the color spectra. Our study suggests that the GO-phosphor hybrid nanoscrolls are suitable candidates for light-emitting applications.