氮掺杂石墨烯的制备及其超级电容性能

以氧化石墨烯(GO)为原料, 尿素为还原剂和氮掺杂剂, 采用水热法合成了氮掺杂石墨烯. 利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外(FTIR)光谱、X 射线衍射(XRD)、X 射线光电子能谱(XPS)、氮气吸脱附分析、电导率和电化学测试对样品的形貌、结构、组成以及电化学性质进行表征. 结果表明:水热条件下尿素能有效地化学还原GO并对其进行氮掺杂; 通过调节原料与掺杂剂的质量比, 可以得到不同氮掺杂含量的石墨烯, 氮元素含量范围为5.47%-7.56% (原子分数); 在6 mol·L^-1的KOH电解液中, 氮元素含量为7.50%的掺杂石墨烯的超级电容性能最优, 即在3 A·g^-1电流密度下首次恒流充放电比电容可达184.5 F·g^-1, 经1200次循环后的比电容为161.7 F·g^-1, 电容保持率为87.6%.

Preparation of Nitrogen-Doped Graphene and Its Supercapacitive Properties

Nitrogen-doped graphene was synthesized by the hydrothermal method with graphene oxide (GO) as the raw material and urea as the reducing-doping agent. The morphology, structure, and components of the as-produced graphene were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption analysis, and electrical conductivity measurements. The results showed that nitrogen was doped into the graphene plane at the same time as the GO sheets were reduced, and the nitrogen content was between 5.47%-7.56% (atomic fraction). In addition, the electrochemical performance of the graphene was tested. Nitrogen-doped graphene with a nitrogen content of 7.50% showed excellent capacitive behavior and long cycle life. The first cycle specific discharge capacitance for the material was 184.5 F·g^-1 when cycled at 3 A·g^-1, and 12.4% losses were found after 1200 cycles in anaqueous electrolyte of 6 mol·L^-1 KOH.