Thin sandwich graphene oxide@N-doped carbon composites for high-performance supercapacitors

Abstract

Compositing graphene oxide (GO) with controllable secondary components is of great significance to achieve carbon materials with high-level physicochemical properties. In this study, thin sandwich composites of GO and N-doped carbon (GO@NdC) were fabricated through controllable deposition of polyvinyl dichloride (PVDC)-dehalogenated carbon on GO; this method exploited the high affinity between PVDC and GO. The thin deposited carbon layers on GO achieved the thicknesses ranging from 1.0 to 2.0 nm. Considering that dehalogenated carbon has been verified to be highly reactive for coupling heteroelements, an overall N content of ∼7.0 at% was obtained with the addition of melamine as a N source. Moreover, the byproducts EtOH and NaCl could tune the composites into open 3D structures in situ, efficiently preventing the thin-layered composites from re-stacking. After activation with KOH, GO@NdC further demonstrated a hierarchical pore structure and large specific surface area. Remarkably, KOH-activated GO@NdC exhibited a high specific capacitance of ∼354 F g⁻¹ and a capacitance retention of >65% (at 10.0 A g⁻¹). Finally, the GO@NdC symmetric supercapacitor also achieved a high specific energy of ∼11.8 W h kg⁻¹ in an aqueous alkaline electrolyte.