Electrophoresis-microwave synthesis of S,N-doped graphene foam for high-performance supercapacitors

Abstract

The three-dimensional self-standing architecture of heteroatom-doped graphene is the ideal electrode material for supercapacitors. However, the facile control of its composition and structure is still a challenge. Herein we have reported a new method of electrochemical-coagulation-type electrophoretic deposition involving a bubble template and subsequent in situ microwave reduction, so as to controllably prepare a sulfur, nitrogen-doped graphene foam (dGF) on ultrathin graphite paper. With the abundant interconnected pores, the high specific surface area of 1806 m² g⁻¹, and the dual-doping of sulfur and nitrogen, the dGF exhibited a high specific capacitance of 354 F g⁻¹ at 0.5 A g⁻¹ and good rate performance (64.7% capacitance retention at 50 A g⁻¹). By virtue of the advantages of the graphite paper as both the deposition substrate and an in situ microwave reduction initiator, the interdigital electrodes were facilely obtained by tailoring the shape of the graphite paper. The assembled flexible supercapacitor had an energy density of 71.5 W h kg⁻¹ at a power density of 0.65 kW kg⁻¹ and retains a specific capacitance of 99.5% after 10 000 charge–discharge cycles. This study provided an ideal flow process to construct a graphene self-standing architecture, which presents potential application value in catalysis, energy storage, and environmental protection.