【作者】 吕维强；

【导师】 杨春晖；

【作者基本信息】 哈尔滨工业大学 ， 无机化学， 2009， 硕士

【摘要】 氢能作为未来的新能源己为必然的发展趋势,氢源的储存是氢能利用系统中最为关键的一环,碳基纳米材料因其独特的结构和性能成为储氢材料研究的热点。石墨烯作为一种新近发现的碳纳米材料,具有比表面大,物化性能稳定,制备工艺简单,原料来源广泛等一系列优点,引起了人们对其储氢性能理论和实验研究的兴趣。本文通过氧化石墨还原法制备石墨烯和石墨烯-纳米铜(银)复合材料,测试它们的电化学储氢性能。同时对几种基于石墨烯的纳米结构材料的储氢性能进行理论计算,来寻找合适储氢材料。采用氧化石墨还原法制备石墨烯。以鳞片石墨为原料,采用改进Hummers法制备氧化石墨,借助超声分散和化学还原,制备出石墨烯。通过XRD、FT-IR、Raman与XPS对石墨、氧化石墨和石墨烯进行结构表征,确定制备过程中的化学组成和结构变化。通过AFM和SEM直接观察样品形貌,确定是否得到单原子层的石墨烯。通过恒电流充放电实验获得石墨烯电化学储氢率为0.14wt%。采用氧化石墨和Cu2+(Ag+)同时还原的方法制备了不同负载量的石墨烯-纳米铜(银)复合材料,纳米铜(银)充当层间阻隔物。XRD测试结果证实负载纳米铜(银)后的石墨烯层间距变大。测试了石墨烯-纳米铜(银)复合材料电化学储氢性能,当铜负载量为39wt%,其比电容量达到最高值67.95mAh/g,储氢量为0.25%,储氢性能提高,但负载银的样品储氢性能下降。采用巨正则蒙特卡罗法计算了石墨烯储氢性能。石墨烯常温储氢性能较差,而在低温77K,100kPa下,质量储氢率可达6wt%以上,体积储氢率达40g/L以上。讨论了石墨烯层间距、缺陷和Li掺杂对储氢性能的影响。计算了几种石墨烯纳米复合结构储氢性能。石墨烯-C60储氢性能比石墨烯差;石墨烯纳米蕾结构储氢性能比石墨烯略好;石墨烯-CNT结构常温储氢性能较好,体积储氢率大,是一种较理想的储氢结构。更多还原

【Abstract】 Hydrogen, as a new energy resource, has been the inevitable trend, while hydrogen storage is the most critical aspect of hydrogen energy utilization system. Carbon-based materials because of its unique structure and properties, has become the hot spot for hydrogen storage. Graphene, a newly discovered carbon nano-materials owns a number of advantages, such as large surface area, physical and chemical stability, simple preparation methods, wide source for raw materials. It has attracted research interest to its hydrogen storage properties both theoretically and experimentally. In this paper, graphene and graphene-nano-copper (Ag) composite materials were prepared by reducing graphite oxide. Their electrochemical hydrogen storage performances were tested. At the same time, to find a suitable hydrogen storage materials, hydrogen storage properties of several graphene-based nano-structured materials are calculated theoretically.Graphite oxide reducing method is adopted to prepare graphene. Flake graphite is used as a raw material, to synthesis graphite oxide(GO) by modified Hummers method. Then graphene is prepared by using ultrasonic dispersion and chemical reduction of GO solution. The Chemical component and structure information of graphite, graphite oxide and graphene were analyzed through XRD, FT-IR, Raman and XPS characterization. AFM and SEM were utilized to observe the morphology of samples, to determine whether a single atomic layer of graphene. The electrochemical hydrogen uptake is 0.14wt%, measured by constant current charge-discharge experiment.In order to prevent overlap between graphene layers, graphene nano-copper (Ag) composite materials with different load content,were prepared by reducing graphite oxide and Cu2 + (Ag+) at the same time. Nano-copper (silver) particles act as barrier XRD conforms that graphene layer spacing become larger after loading nano-copper (silver). Electrochemical hydrogen storage properties of the graphene-nano-copper (silver) composite materials were measured. The results show that with copper load content of 39wt%, the capacity reaches the highest value 67.95mAh/g. The conresponding hydrogen storage uptake is 0.25%, which is higher than pure graphene. However, the hydrogen storage performance of samples load with silver bacomes worse. Grand canonical Monte Carlo method is adoped to calculate the hydrogen storage properties of graphene. Grpahene has a poor hydrogen storage properties at room temperature. While at low temperatures,such as in the 77K, 100kPa, the gravimetric hydrogen uptake reaches more than 6wt%, the volumatric hydrogen uptake come to above 40g/L. The influence of graphene layer space, defects and Li doping on the hydrogen storage properties.are discussed hydrogen storage performance several graphene nano-composite structure wre calculated. Graphene -C60 has a poor performance, while graphene nanobud graphene shows raletaviely good hydrogen storage properties. graphene-CNT owns a high volumatric hydrogen uptake and shows good hydrogen storage performance at room temperature.更多还原