A metallated graphene oxide foam with a carbon nanotube shell for an enhanced capacitance device

Abstract

Single and multimetallic interfacial sites are promising for enhancing current density, power density, and capacitance. Graphene-based composites with a three-dimensional (3D) foam architecture and metal incorporation are prospective materials to investigate the migration of electrons along the interfaces of nanotube architecture. We present a fabrication strategy for metallated reduced graphene oxide foam (M-rGO foam) grown as a single piece using a graphene suspension and multi-walled carbon nanotube (MWCNT)-like tubular structure-containing trimetallic (Ni, Co, and Zn) zeolitic imidazolate framework derived NC at 700 °C (C-ZIF-700-NC) as the parent material with rich metal-doped interfaces. During the formation of the composite between graphene oxide and M-ZIF-700 NC, L-ascorbic acid acts as a reducing agent in an aqueous medium at 75 °C for 8 h. The M-rGO foam architecture incorporates metal nanoparticles, such as cobalt, nickel, and zinc, for capacitance enhancement because of possible ionic conductivity in the hierarchical metallated interface architecture. The M-rGO foam delivers an outstanding gravimetric capacitance of 1013.47 F g⁻¹ at a scan rate of 5 mV s⁻¹ and retains an extraordinary gravimetric capacitance of 450.81 F g⁻¹ even at a higher scan rate of 100 mV s⁻¹ with high-rate capability. It has a prolonged capacitance retention of 94% at 10 000 cycles. The symmetric supercapacitor device (SSD) of the M-rGO foam achieved an ultrahigh energy density of 44.93 Wh kg⁻¹ at a power density of 749.9 W kg⁻¹.