氮掺杂石墨烯—四氧化三铁的制备及催化性能研究

发布时间：2018-10-23 10:07

【摘要】：石墨烯是一种新型纳米材料,它独特的结构使其具有卓越的电学性能和物理性能,广泛应用在纳米电子学、电子传感器、晶体管、太阳能电池、催化剂等多种领域。但石墨烯没有带隙、较为惰性、不易与其他材料复合。向石墨烯中引入氮原子,形成氮掺杂石墨烯,可以改变其电子结构,并打开石墨烯的带隙,从而使其具有更广泛的应用价值。本文采用水热法合成氮掺杂石墨烯,分别以氨水和甲酰胺为氮源与氧化石墨烯反应,生成氮掺杂石墨烯。通过调控反应条件,得到制备氮掺杂石墨烯的最适条件,即:以氨水为氮源,氧化石墨烯与氨水的质量比为1:24、反应温度为160℃、反应时间为12 h时,产品中氮原子数百分比为9.08%,氮元素主要以吡啶氮的形式掺杂到石墨骨架当中;以甲酰胺为氮源,氧化石墨与甲酰胺的质量比为1:100、反应温度为140℃、反应时间为12 h时,产品中氮原子数百分比为5.67%,氮元素主要以吡咯氮的形式掺杂到石墨骨架当中。以尿素为氮源,按照文献42的方法制得了氮掺杂石墨烯,并对其进行了表征。结合氨水、甲酰胺、尿素这三种氮源的实验结果,对石墨烯氮掺杂机理进行了推断。氮掺杂石墨烯具有一定的催化性,为了在反应结束后便于将其从反应体系中分离出来,可向氮掺杂石墨烯中引入磁性四氧化三铁,将其制成磁性复合材料。本文利用水热法,以氧化石墨烯和尿素铁为原料、氨水为氮源、乙二醇和氨水为还原剂、聚乙烯吡咯烷酮(PVP)为分散剂,在反应温度为200℃条件下反应12 h,一步反应生成氮掺杂石墨烯-四氧化三铁复合材料。利用红外光谱,X射线衍射光谱、X射线光电子能谱、扫描电镜、透射电镜等手段对制备的复合材料进行表征,结果表明,四氧化三铁嵌入在氮掺杂石墨烯中,粒径大多小于200 nm;X射线光电子能谱显示,碳的原子百分比为70.34%,氮的原子百分比为5.43%,氧的原子百分比为21.23%,铁的原子百分比为3%,氮元素主要以吡啶型为主。用氮掺杂石墨烯-四氧化三铁复合材料作为甲苯氧化反应的催化剂,双氧水为氧化剂,并从反应温度、反应时间、溶剂的种类、双氧水加入量、催化剂用量、催化剂种类这六个方面,来考察影响甲苯催化氧化的因素。其中,反应温度60℃、反应时间12 h、采用冰醋酸为溶剂、甲苯与双氧水比例为1:4、催化剂0.2 g、催化剂吡啶氮含量最高时,所得的甲苯氧化物苯甲醛的收率最高。
[Abstract]:Graphene is a new kind of nano-material, which has excellent electrical and physical properties due to its unique structure. It is widely used in nanoelectronics, electronic sensors, transistors, solar cells, catalysts and other fields. However, graphene has no band gap, is inert, and is not easy to be combined with other materials. The introduction of nitrogen atoms into graphene to form nitrogen-doped graphene can change its electronic structure and open the band gap of graphene so that it has more extensive application value. In this paper, nitrogen-doped graphene was synthesized by hydrothermal method. Nitrogen doped graphene was synthesized by the reaction of ammonia and formamide with graphene oxide. The optimum conditions for preparing nitrogen-doped graphene were obtained by adjusting the reaction conditions, namely, when ammonia was used as nitrogen source, the mass ratio of graphene oxide to ammonia water was 1: 24, the reaction temperature was 160 鈩，

本文编号：2288914