Synthesis and Supercapacitor Performance of Histidine-functionalized Carbon Dots/Graphene Aerogel

Abstract

Histidine-functionalized carbon dot/graphene aerogel (His-CDs/GA) were synthesized via the one-step hydrothermal method. The as-prepared His-CDs/GA exhibits unique three-dimensional porous structure, rich nitrogen and oxygen-containing functional groups, which facilitate the rapid diffusion of electrolyte ions and provide more active sites. When the mass ratio of GO and His-CDs is 2:1, the specific capacitance of His-CDs/GA-2 reaches 304 F• g-1 at a current density of 1 A• g-1 , which increases 76.7% compared with that of GA (172 F• g-1). With the current density increasing from 1 A• g-1 to 50 A• g-1 , the specific capacitance retention of His-CDs/GA-2 achieves 71.4%. The specific capacitance of His-CDs/GA-2 still remains 93.5% over 30000 cycles at 10 A• g-1. In addition, a symmetrical supercapacitor assembled by His-CDs/GA possesses a high energy density of 10.14 Wh/kg at a power density of 250 W/kg, and good cyclic performance with 88.4% capacitance retention at 5 A• g-1 over 20000 cycles. The results show that His-CDs/GA is a promising electrode material for supercapacitors.