氮掺杂石墨烯凝胶的制备与表征

为了拓展石墨烯凝胶在超级电容器方面的应用，采用氨水、水合肼作为还原剂和掺杂剂，通过与氧化石墨烯的水热反应制备了氮掺杂石墨烯凝胶，并采用X射线光电子能谱，元素分析、扫描电子显微镜对产物的结构与微观形貌进行表征，采用循环伏安法和计时电位法测试其电化学性能. 结果表明，在氧化石墨烯的水热反应体系中引入氮掺杂剂，不仅能得到具有三维多孔结构的有一定力学强度的凝胶，而且经过氮掺杂后石墨烯的电化学性能较纯石墨烯的有明显提高. 当扫描速率为10 mV/s时，氮掺杂石墨烯的比电容为196 F/g；当电流密度为1 A/g时，氮掺杂石墨烯的比电容达到217 F/g，当循环伏安扫描1 000圈后，电容保持率达到80%. 这表明氮掺杂石墨烯凝胶具有优异的电化学性能，在超级电容器方面有很好的应用前景.

Preparation and Characterization of Nitrogen-Doped Grapheme Hydrogel

For the future application of graphene hydrogel in supercapacitors, nitrogen-doped grapheme hydrogels were prepared by the hydrothermal method using ammonia and hydrazine hydrate as the reducing agent and nitrogen resource, respectively. X-ray photoelectron spectroscopy, elemental analysis and scanning electron microscope were carried out to characterize the structure and morphology of the nitrogen-doped graphene hydrogel. Moreover, the electrochemical performance was measured by cyclic voltammetry and galvanostatic charge/discharge. The result shows that when nitrogen-containing agents are added during the hydrothermal process of graphene oxide, the nitrogen-doped graphene hydrogel with three-dimension porous structure and certain mechanical strength can be obtained. The specific capacitance of nitrogen-doped graphene hydrogel also increases because of nitrogen-doping. The specific capacitance of nitrogen-doped graphene hydrogel is 196 F/g and 217 F/g at the scanning rate of 10 mV/s and current density of 1 A/g, respectively. The specific capacitance of nitrogen-doped graphene hydrogel can keep 80% after 1 000 cycles of cyclic voltammetry. It indicates that nitrogen-doped graphene hydrogel has good electrochemical properties for the application of supercapacitor electrode in future.