硫氮共掺杂石墨烯的制备及其电化学性能

摘要

The modified Hummers method was used to prepare graphite oxide (GO) through freeze drying. The sulfur-nitrogen co-doped graphene samples were then synthesized by one-step hydrothermal method using thiourea as dopant and reductant,with mass ratios of GO to thiourea of 1:10, 1:20, 1:30, 1:40 respectively. The microstructure and morphology of the as-produced graphene were characterized by X-ray diffraction, field emission scanning electron microscope, Raman spectroscopy, X-ray photoelectron spectroscopy and nitrogen adsorption-desorption analysis. The electrochemical performances of the samples were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge (GCD) technology. The results showed that the sulfur-nitrogen co-doped graphene had the highest sulfur content of 1.86% and nitrogen content of 7.73%, with a specific surface area of 175.8m2/g and the pore sizes were narrowly distributed in between 3—5nm when the mass ratio of GO:thiourea is 1:30. At 1A/g current density, SNG had a specific capacitance of 197.2F/g, and only 10% were lost after 2000 charge and discharge cycles.%采用改进的Hummers方法经冷冻干燥制备氧化石墨烯(GO),以硫脲作为还原剂和掺杂剂,按GO与硫脲的质量比为1:10、1:20、1:30、1:40的用量分别加入硫脲,采用一步水热法合成硫氮共掺杂石墨烯.通过X射线粉末衍射(XRD)、场发射扫描电子显微镜(FESEM)、拉曼光谱(Raman)、X射线光电子能谱(XPS)、氮气吸脱附分析等手段表征了样品的微观结构和形貌,通过循环伏安、电化学交流阻抗、恒流充放电技术对样品进行电化学性能测试.结果表明:当GO:硫脲=1:30(质量比)时,得到的硫氮共掺杂石墨烯(SNG)中硫掺杂量最高为1.86%(质量分数)、氮掺杂质量分数最高为7.73%,比表面积达175.8m2/g,且具有较窄的孔径分布,集中在3～5nm.在电流密度为1A/g时,SNG的比电容最高达197.2F/g,经过2000次充放电循环后,比电容为177.3F/g,电容保持率达90%.