氮掺杂石墨烯量子点/MOF衍生多孔碳纳米片构筑高性能超级电容器

Building a High-Performance Supercapacitor with Nitrogen-Doped Graphene Quantum Dots/MOF-Derived Porous Carbon Nanosheets

首先采用溶液法在碳布上生长Co-MOF二维纳米片,通过高温退火和刻蚀后得到MOF衍生多孔碳纳米片。以Co-MOF衍生的多孔碳纳米片/碳布(CNS/CC)作为碳基骨架,采用电化学沉积法负载高活性氮掺杂石墨烯量子点(N-GQDs),制备得到分级多孔结构的N-GQD/CNS/CC复合材料。组装成自支撑且无粘结剂的N-GQD/CNS/CC电极,当电流密度为1 A·g^-1时,其比电容高达423 F·g^-1。通过储能机制和电容贡献机制的研究表明,在碳纤维上原位生长的具有高双电层电容的CNS和表面负载具有高赝电容的N-GQDs之间相互协同作用,使得N-GQD/CNS/CC电极具有高电容性能,是一种理想的超级电容器电极材料。电极材料的高导电、分级多孔结构有利于电子的传输和电解质离子的扩散,具有良好的动力学性能,能快速充放电和具有优异的倍率特性。将电极组装成对称型超级电容器,功率密度为250 W·kg^-1时对应的能量密度达到7.9 Wh·kg^-1,且经过10000次循环后电容保持率为91.2%,说明氮掺杂石墨烯量子点/MOF衍生多孔碳纳米片复合材料是一种电化学性能稳定的具有高电容性能的全碳电极材料。

Co-MOF two-dimensional nanosheets were first grown on a carbon cloth by solution method,and MOF-derived porous carbon nanosheets were obtained after high temperature annealing and etching process.Co-MOF derived porous carbon nanosheets/carbon cloths(CNSs/CC)was used as the carbon-based framework,and highly active nitrogen-doped graphene quantum dots(N-GQDs)were loaded by electrochemical deposition to prepare hier-archical porous structures N-GQD/CNS/CC composite material as electrode material for supercapacitors.The N-GQD/CNS/CC electrode,as a self-supporting and adhesive-free electrode,delivered a specific capacitance of 423 F·g^-1 at 1 A·g^-1.According to the mechanism of energy storage and capacitance contribution,the N-GQD/CNS/CC composite is an ideal supercapacitor electrode material with high capacitance,due to synergetic effect between CNS grown in situ on carbon fiber with high double-layer capacitance and N-GQDs loaded on the surface with high pseudo-capacitance.The highly conductive,hierarchical porous structure of the electrode material is beneficial to the electron transport and the diffusion of electrolyte ions,which presents good kinetic performance,high rate perfor-mance and rapid charge-discharge capability.A symmetrical supercapacitor based on N-GQD/CNS/CC electrode exhibited a high energy density of 250 W·kg^-1 at power density of 7.9 Wh·kg^-1,while the capacitance retention after 10000 cycles reached 91.2%,which indicates that the N-GQD/CNS/CC composite is an all-carbon electrode materi-al with stable electrochemical performance and high capacitance performance.