碳基纳米材料的设计合成及其电催化性质的研究

发布时间：2018-03-28 13:33

本文选题：碳基纳米材料　切入点：掺杂　出处：《苏州大学》2016年硕士论文

【摘要】：随着经济的高速发展,全球对于能源的消耗也日益增加。但是,传统能源绝大多数是不可再生的,并在使用过程中会对环境造成污染。因此,人们迫切希望找到能够替代传统化石燃料的可再生清洁能源。电化学的主要研究内容是电能和化学能之间的转换,它能够为解决能源问题提供一些可行的途径。碳基纳米材料因拥有十分优异的物理、化学性质,在生物传感器和电化学等领域具有广泛的应用前景。在本文中,我们通过简单的化学方法合成了三种不同的碳基纳米材料,包括具有多孔形态的三元(氮,磷,硼)共掺杂纳米碳材料(NPBC),碳量子点(CQDs)、SnO_2和Co_3O_4的复合物以及CQDs和MoS_2复合物,并研究了它们的电催化性质及催化机理。主要工作内容如下:(1)通过调控初始磷酸和硼酸加入量,采用一步热解法合成了一系列具有多孔形态的三元(氮,磷,硼)共掺杂纳米碳材料(NPBC),并将它们作为电催化剂用于催化氧还原反应(ORR)。实验结果表明当P和B的初始原料摩尔比为3:7时,该催化剂(标记为NPBC-2)表现出最佳催化活性。通过透射电镜,扫描电镜和氮气吸附脱附测试证明了该三元掺杂材料具有膜状多孔结构,并且其比表面积达到89.5 m~2·g~(-1)。电化学测试结果表明:在0.1 M的KOH溶液中,该多元掺杂碳基催化剂(NPBC-2)的ORR催化性能明显高于单掺杂(NC)和二元掺杂催化剂(NPC或者NBC),体现在较正的初始电位(-0.11V vs SCE),长时间的稳定性和极好的抗甲醇毒化能力。(2)通过简单水热法合成了一系列碳量子点(CQDs),二氧化锡(SnO_2)和四氧化三钴(Co_3O_4)的复合物,并将它们应用于催化水氧化反应。电化学测试结果表明:Sn和Co初始摩尔比为1:3的复合物(记为CQDs/SnO_2-Co_3O_4)表现出了最佳催化活性。在碱性介质中,相较于单独的Co_3O_4或SnO_2-Co_3O_4催化剂,该CQDs/SnO_2 Co_3O_4催化剂表现出了更负的起始电位(~0.56 V),大的电流密度和良好的稳定性。进一步的研究证明:CQDs在催化剂表面上有效地抑制了该复合物在碱性溶液中的溶解,使其形成了一个稳定的结构,表现出长时间的电催化稳定性。(3)利用水热法合成了不同CQDs和Mo质量比的CQDs/MoS_2复合物,并将其作为电催化剂用于催化电化学析氢反应(HER)。其中CQDs/Mo质量比为1.13%的CQDs/MoS_2复合物具有最佳HER催化活性。CQDs/MoS_2在经可见光光照处理30分钟后(记为CQDs/MoS_2-L30),其电催化析氢性能明显优于未经光处理的CQDs/MoS_2催化剂。CQDs/MoS_2-L30高效的HER催化活性主要表现在:在0.5 M的H_2SO_4溶液中,具有较小的过电势(当电流密度为10mA cm~(-2)时,过电势为~0.125V),大的电流密度,较小的塔菲尔值(45 mV/decade)和长时间的稳定性。综合红外光谱和X射线光电子能谱分析,CQDs/MoS_2-L30具有极好HER催化性能主要归因于高效的电子传输效率,S~(4+)数量的减少及S_2~(2-)和S~(2-)量的增多。
[Abstract]:With the rapid development of economy, the global energy consumption is increasing day by day. However, most of the traditional energy sources are non-renewable and will pollute the environment in the process of use. People are eager to find renewable and clean energy sources that can replace traditional fossil fuels. The main study of electrochemistry is the conversion between electricity and chemical energy. Because of its excellent physical and chemical properties, carbon based nanomaterials have a wide range of applications in biosensors and electrochemistry. We have synthesized three different kinds of carbon based nanomaterials by simple chemical method, including the ternary (nitrogen, phosphorus, boron) co-doped carbon materials with porous morphology, the carbon quantum dots (CQDs), the complexes of Co_3O_4 and SnO2, and the complexes of CQDs and MoS_2. Their electrocatalytic properties and catalytic mechanism are studied. The main work is as follows: (1) A series of porous ternary (nitrogen, phosphorus) have been synthesized by one step pyrolysis by controlling the initial phosphoric acid and boric acid addition. The results show that when the initial molar ratio of P and B is 3:7, they are used as electrocatalysts for catalytic oxygen reduction reaction. The catalyst (labeled NPBC-2) showed the best catalytic activity. The results of transmission electron microscopy, scanning electron microscopy and nitrogen adsorption and desorption test showed that the ternary doped material had a porous membrane structure. The specific surface area is 89.5 m ~ 2 g ~ (-1) 路L ~ (-1). The electrochemical test results show that in 0.1 M KOH solution, the specific surface area is 89.5 m ~ 2 g ~ (-1) ~ (-1). The ORR catalytic performance of the multicomponent doped carbon based catalyst (NPBC-2) is obviously higher than that of mono-doped ORR and binary doped catalyst, which is reflected in the positive initial potential of -0.11V vs SCEN, long time stability and excellent methanol-resistant ability. A series of complexes of carbon quantum dots (CQDsO), tin dioxide (Sno _ 2) and Cobalt _ 2O _ (3) O _ (4) have been synthesized by hydrothermal method. The electrochemical measurements showed that the complexes with the initial molar ratio of 10: Sn and Co at 1:3 (denoted as CQDsS / SnO _ 2-Co3O4) exhibited the best catalytic activity. In alkaline medium, compared with the single Co_3O_4 or SnO_2-Co_3O_4 catalysts, The catalyst exhibited a more negative initial potential of 0.56V ~ (-1), high current density and good stability. Further studies have shown that the solution of the complex in alkaline solution is effectively inhibited by the presence of the CQDs/SnO_2 / CQDs on the surface of the catalyst. A stable structure was formed, showing a long time electrocatalytic stability. (3) CQDs/MoS_2 complexes with different mass ratios of CQDs and Mo were synthesized by hydrothermal method. The CQDs/MoS_2 complex with 1.13% CQDs/Mo has the best HER catalytic activity. CQDs / MoS2 was treated by visible light for 30 minutes (CQDsP MoS2-L30C). The catalytic activity of CQDs/MoS_2 catalyst. CQDsr / MoSs-L30, which is superior to that of untreated HER catalyst, is as follows: in 0.5 M H_2SO_4 solution, the catalytic activity of CQDs / Mos / MOS _ 2-L30 is as follows: 1. The overpotential is 0.125 V ~ (-1) when the current density is 10mA / cm ~ (-2), and the current density is large, and the overpotential is 0.125 V ~ (-1), and the overpotential is 0.125 V ~ (-1). Combined with infrared spectroscopy and X-ray photoelectron spectroscopy, the excellent catalytic performance of CQDsMoS2-L30 is mainly attributed to the decrease in the number of highly efficient electron transport efficiency and the increase of S2P and S2-2).
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O643.36;TB383.1

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