A simple strategy toward hierarchically porous graphene/nitrogen-rich carbon foams for high-performance supercapacitors

Abstract

Three-dimensional nitrogen-rich porous carbon materials (NPCs), with advantageously tuned physicochemical properties through nitrogen functionalities, have become the research hotspot of energy storage. As electrodes for supercapacitors, NPCs fabricated via a facile strategy are highly desirable to improve the limited performance of N-doped species and obtain high specific capacitance. Herein, a graphene/nitrogen-rich carbon foam with a 3D hierarchically porous architecture has been achieved through assembling graphene oxide sheets into melamine foam. The obtained foam with meso- and micro-pores, nitrogen-enriched content (11.6 at%), and a large surface area (943.7 m² g⁻¹) delivers enhanced energy storage capabilities of 324, 229, and 196 F g⁻¹ at current densities of 0.1, 1, and 10 A g⁻¹ in a 6 mol L⁻¹ KOH electrolyte, respectively. Moreover, the as-prepared material shows an appreciable capacitance of up to 213 F g⁻¹ at 0.1 A g⁻¹, along with excellent cycling stability (99% retention after 10 000 cycles in a PVA/KOH gel electrolyte) in the related fabricated symmetric solid-state supercapacitors.