Zhao Jinxing, Liu Chang, Xiang Kun, Cheng Qi, Li Yuxiao, Lin Huan, Lee Kuan-Ting, An Liang, Tang Shun, Cao Yuan-Cheng, Liang Jiyuan
J Nanosci Nanotechnol. 2018 Oct 1;18(10):6949-6956. doi: 10.1166/jnn.2018.15454.
Nitrogen doped carbon nanocage with graphitic shell (NGCS) was fabricated through in-situ solid reaction between calcium acetate and dicyandiamide in an inert atmosphere followed by acid etching. The role played by the calcium acetate (Ca(Ac)2) and dicyandiamide (DCD) during the synthesis process is one-stone-two-birds. Calcium acetate plays multiple functions: template agent, graphitization catalyst, and carbon source. Dicyandiamide can be considered as the nitrogen sources and the chemical reaction agent that can be reacted with calcium acetate to form it into CaCN2. The NGCS obtained at 800 °C has a specific surface area of 420 m2/g and nitrogen content of 8.87 at%. The excellent electrochemical performance can be attributed to the combination effects of porous structure, nitrogen doping and graphitized nanocage shell of NGCS electrode. The hollow structure serves as the reservoir for fast electrolyte ion supplement. Nitrogen groups not only improve the wettability of interfaces between carbon surface and electrolyte, but also generate extra pseudocapacitance through redox reaction. The graphitic carbon nanocage shell can enhance the conductivity and facilitates the fast charge transfer. At a current density of 0.5 A/g, the specific capacitance of the NGCS-800 electrode is 215 F/g. Furthermore, the NGCS-800 electrode exhibits excellent rate capability (80% capacitance retention at 10 A/g) and outstanding cycling stability (96.89% capacitance retention after 5000 cycles). These intriguing results demonstrate that nitrogen doped carbon with graphitic shell will be highly promising as electrode materials for supercapacitors and other energy storage and conversation applications.
通过在惰性气氛中乙酸钙与双氰胺之间的原位固相反应，随后进行酸蚀刻，制备了具有石墨壳的氮掺杂碳纳米笼（NGCS）。乙酸钙（Ca(Ac)₂）和双氰胺（DCD）在合成过程中起到了一石二鸟的作用。乙酸钙具有多种功能：模板剂、石墨化催化剂和碳源。双氰胺可被视为氮源以及能与乙酸钙反应形成CaCN₂的化学反应剂。在800℃下获得的NGCS比表面积为420 m²/g，氮含量为8.87 at%。优异的电化学性能可归因于NGCS电极的多孔结构、氮掺杂和石墨化纳米笼壳的综合作用。中空结构作为快速补充电解质离子的储存库。氮基团不仅提高了碳表面与电解质之间界面的润湿性，还通过氧化还原反应产生额外的赝电容。石墨化碳纳米笼壳可提高导电性并促进快速电荷转移。在电流密度为0.5 A/g时，NGCS-800电极的比电容为215 F/g。此外，NGCS-800电极表现出优异的倍率性能（在10 A/g时电容保持率为80%）和出色的循环稳定性（5000次循环后电容保持率为96.89%）。这些有趣的结果表明，具有石墨壳的氮掺杂碳作为超级电容器及其他能量存储和转换应用的电极材料具有很大的潜力。
