A Simple Route to Porous Graphene from Carbon Nanodots for Supercapacitor Applications
A Simple Route to Porous Graphene from Carbon Nanodots for Supercapacitor Applications
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DOI：
10.1002/adma.201704449
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发表时间：
2018-02-22
影响因子：
29.4
通讯作者：
Kaner, Richard B.
中科院分区：
文献类型：
--
作者：
Strauss, Volker;Marsh, Kris;Kaner, Richard B.
提出了一种将生物分子基碳纳米点（CND）转化为具有优异电化学性能的高表面积3D石墨烯网络的简便方法。最初，根据先前公布的方案，通过微波辅助柠檬酸和尿素的热处理来合成CND。接下来，CND在无氧环境中的管式炉中退火至400摄氏度。最后，通过用红外激光照射，将热处理的CND的膜转化为开放的多孔3D乱层石墨烯（3D-ts-graphene）网络。基于扫描电子显微镜、透射电子显微镜、X射线光电子能谱、X射线衍射、傅里叶变换红外光谱和拉曼光谱的表征，提出了CND的热处理和随后的激光转化为3D-ts-石墨烯的可行反应机理。3D-ts-石墨烯网络显示出优异的形态学特性，如分级多孔结构和高表面积，以及有前途的电化学性能。例如，在560 A L-1的电流密度下实现了具有27.5 mF L-1的体积电容的接近理想的电容行为，这对应于在711 W L-1的功率密度下的24.1 mWh L-1的能量密度。值得注意的是具有3.44 ms的时间常数的极快的充电-放电循环速率。
A facile method to convert biomolecule-based carbon nanodots (CNDs) into high-surface-area 3D-graphene networks with excellent electrochemical properties is presented. Initially, CNDs are synthesized by microwave-assisted thermolysis of citric acid and urea according to previously published protocols. Next, the CNDs are annealed up to 400 degrees C in a tube furnace in an oxygen-free environment. Finally, films of the thermolyzed CNDs are converted into open porous 3D turbostratic graphene (3D-ts-graphene) networks by irradiation with an infrared laser. Based upon characterizations using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and Raman spectroscopy, a feasible reaction mechanism for both the thermolysis of the CNDs and the subsequent laser conversion into 3D-ts-graphene is presented. The 3D-ts-graphene networks show excellent morphological properties, such as a hierarchical porous structure and a high surface area, as well as promising electrochemical properties. For example, nearly ideal capacitive behavior with a volumetric capacitance of 27.5 mF L-1 is achieved at a current density of 560 A L-1, which corresponds to an energy density of 24.1 mWh L-1 at a power density of 711 W L-1. Remarkable is the extremely fast charge-discharge cycling rate with a time constant of 3.44 ms.