不同氮源对掺氮石墨烯的结构和性能的影响

Effect of Different Nitrogen Sources on Structure and Properties of Nitrogen-doped Graphene

先用改进的Hummers方法冷冻干燥制备氧化石墨(GO),再分别以水合肼、氨水、乙二胺、尿素作为掺氮剂和还原剂用一步水热法合成掺氮石墨烯。使用傅里叶变换红外光谱(FT-IR)、X射线粉末衍射(XRD)、场发射扫描电子显微镜(FESEM)、X射线光电子能谱(XPS)、同步热重分析(TGA)、氮气吸脱附分析等手段表征了样品的微观结构和形貌,应用循环伏安、电化学交流阻抗、恒流等充放电技术测试了样品的电化学性能。结果表明:四种掺氮剂皆能有效还原GO,制备出掺氮含量(质量分数)分别为4.99%,6.35%,7.70%和9.18%的石墨烯。氮元素以"pyridinic N"、"pyrrolic N"、"graphitic N"三种形式掺杂到石墨烯的晶格中。由乙二胺和尿素还原制备的掺氮石墨烯比电容可达187.6 F·g^(-1)和191.6 F·g^(-1),电化学性能最高。

Graphite oxide（GO） was prepared via freeze-drying process of a modified Hummers method and then nitrogen-doped graphene was synthesized by one-step hydrothermal method with hydrazine hydrate, ethylenediamine, ammonia and urea as nitrogen sources and reductants respectively.The microstructure and morphology of the as-produced graphene were characterized by means of Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscope, X-ray photoelectron spectroscopy, synchronous thermogravimetric analyzer and nitrogen adsorption-desorption analyzer. The electrochemical performance of the prepared products was assessed by means of cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic charge/discharge technology. Results show that the four nitrogen-containing agents could effectively reduce GO to produce different graphenes, the corresponding nitrogen content（in mass fraction） of which is 4.99%, 7.7%, 6.35% and9.18%, respectively. The doped-N atoms coupled into the graphene lattice in forms of ＂pyridinic N＂, ＂pyrrolic N＂ and ＂graphitic N＂. The specific capacitance of the nitrogen-doped graphene prepared with ethylenediamine and urea as reductants could reach 187.6 F·g^（-1） and 191.6 F·g^（-1） respectively, implying excellent electrochemical performance.