Nanoscale/microscale porous graphene-like sheets derived from different tissues and components of cane stalk for high-performance supercapacitors

Abstract

Different biomass components have different effects on the microstructures and physicochemical properties of biocarbons. And the properties of biocarbons still need to be further improved. Nanoscale/microscale graphene-like sheets are synthesized with KOH as micropore-forming agent, \[\hbox{Fe}(\hbox{NO}_{3})_{3}\cdot \hbox{9}\,\hbox{H}_{2}\hbox{O}\] as mesopore-forming agent and graphite catalyst. It is systematically researched to get the effects of biomass components on them. Cane sugar can form flat graphene-like nanosheets with high conductivity. Their performance drops sharply at \[100\,\hbox{A g}^{-1}\], indicating that biocarbons need a support of carbon skeleton to operate normally at high current density. Bagasse pith contains amount of cellulose and hemicellulose, which are good for forming pores. Bagasse pith-derived graphene-like sheets possess large specific surface area (\[2923.58\,\hbox{m}^{2}\,\hbox{g}^{-1}\]), high specific capacitance (\[514.14\,\hbox{F g}^{-1}\] at \[0.3\,\hbox{A g}^{-1}\] and \[372.57\,\hbox{F g}^{-1}\] at \[100\,\hbox{A g}^{-1}\]) and high energy density. Due to homogeneous coated doping with graphene-like nanosheets, sugarcane pith-derived graphene-like sheets possess low impedance (\[\text{R}_{\mathrm{s}}=0.02\,\Omega \]), high rate capability (maintained 82.34% from 0.3 to \[100\,\hbox{A g}^{-1}\]) and high cycling stability (maintained 101.51% after 5000 cycles), which is better than lots of graphene doping. Sugarcane skin contains more lignin which has hexagonal carbon rings. The graphitization extent of sugarcane skin-derived graphene-like sheets is significantly high. The results provide references to select carbon precursors, and show a novel graphene-like doping method which is suitable for different materials and various fields.