Template-assisted construction of N,O-doped mesoporous carbon nanosheet from hydroxyquinoline-Zn complex for high-performance aqueous symmetric supercapacitor

Developing porous carbon materials with open accessibility and electro-active functionalities is essential for the enhancement of supercapacitive performance such as energy density and rate capability. Herein, for the first time, a hydroxyquinoline-Zn complex was adopted to fabricate N,O co-doped mesoporous carbon using a template-assisted method for morphology construction. We used sheet-like Mg(OH)(2) as template to achieve nanosheet morphology and as agent to preserve oxygenic functionality. Meanwhile, the zinc oxide self-generated upon carbonization acts as template for mesopore formation. The ZnMgC973 nanosheet obtained under optimized conditions is rich in mesoporosity, displaying large surface area (816 m(2)/g), high electro-active functionalities (17.6 atom% of O and 4.4 atom% of N) and homogenous distribution of elements. Benefited from these unique features, ZnMgC973 is a promising candidate for energy storage. When applied as electrode of aqueous symmetric supercapacitor in 1.0 M Na2SO4, ZnMgC973 works excellently well within the working voltage of 0-2 V, displaying large capacitance retention of 72% at current density from 1 to 20 A/g, maximum energy density of 30.6 Wh/kg at power density of 2000 W/kg (maintaining 20.5 Wh/kg at high power density of 39 620 W/kg), and 96% capacitance retention after 10 000 continual charge/discharge cycles.