功能化石墨烯的可控有序组装研究

 2022-02-22 07:02

论文总字数:26635字

摘 要

石墨烯可以作为免疫传感器载体、各种电子器件、酶催化反应器载体和能量储存及转化等领域极其优良的电极材料。超大的比表面积是单层石墨烯所具有的最为突出的结构特点,不但如此,石墨烯的这种结构特点还使得石墨烯材料本身的优异的导电性能和较为突出的电化学稳定性得到更好的展现。与此同时,同时石墨烯片层之间存在π-π键,导致单层的石墨烯较为容易发生片层之间的堆叠现象,进而使得石墨烯材料原本较大的比表面积和优良的导电性能大大降低,这种情况就极大地限制了石墨烯作为电极材料的应用前景。所以,如何能够高度保留石墨烯原本的各种优异特性成为一个关键的课题,对此,我们的方案是将纳米级尺寸的二维石墨烯通过物理化学手段组装成高级的、有序的三维结构,这样不仅达到预设目标,而且能够通过调控石墨烯的空间结构和形貌获取其更多的性能,在很大程度上拓展其应用领域。

虽然,石墨烯具有高迁移率、室温量子霍尔效应、高热导率及对可见光的高透射率等优点,这些赋予了石墨烯多种优异的物理化学特性,但是,其完美的二元对称结构也造成了石墨烯缺少调制的空间,上面对于二维石墨烯的三维组装显然是改善这一缺陷的一种很好的思路,但是与此同时,如果能够在石墨烯晶格内引入异质原子,从而打破石墨烯对称结构增加活性位点和数量,提高石墨烯的催化性能。特别地,三维多孔的石墨态氮化碳聚合材料因为其结构中,氮原子与碳原子极具规律的交错性排布使得石墨态氮化碳具有极其良好的空间结构和光电性能,氮元素混杂于碳原子中的石墨态氮化碳聚合材料的结构单元中产生的具有活性的区域,可以显著增加石墨烯材料的电催化还原性能,从而拥有在储能、电催化、传感器等领域的广泛应用前景。

本文的研究内容:

一,选择使用软模板法,并且以氢气泡为软模板,通过电化学的还原沉积的手段制备出多孔三维结构的石墨烯电极材料,并探究了反应时间、反应电压、表面活性剂的类别及浓度对于产物结构性能的影响。对于三维大孔石墨烯材料的被还原的程度、光电催化转化的性能以及石墨烯的空间结构的表征选择使用拉曼光谱、X射线电子能谱、扫描电子显微镜和电化学等手段,并探究了其电化学性质。

二,选用三聚氰胺为富氮前驱体,选择三维多孔石墨修饰的FTO为基底,通过热缩聚过程在制备三维多孔石墨烯/g-C3N4修饰电极,该修饰电极具有良好的光电响应。

关键词:软模板,氢气泡,氮化碳聚合物,FTO,石墨烯,光电催化

Preparation and optical properties of three-dimensional porous composite graphene / g-C3N4

Abstract

Graphene can be used as a carrier immune sensor, a variety of electronic devices, enzymatic reactor carrier and energy storage and conversion in areas such as extremely good electrode material. Large specific surface area of ​​the structural characteristics of graphene has the most prominent, not only that, this structure also enables the characteristics of graphene graphene material itself excellent conductivity and electrochemical stability of the more prominent better It shows. At the same time, while graphene sheets between π-π bond, resulting in a monolayer of graphene is more likely to occur between the sheet stacking phenomenon, thereby making the original graphene larger specific surface area and excellent conductivity greatly reduced, this situation has greatly limited the prospects of graphene as an electrode material. So, how can a high degree of retention of the original graphene various excellent characteristics as a key issue, for which our program is a two-dimensional nano-sized graphene by physical and chemical means to higher assembly, ordered three-dimensional structure this not only reach a preset goal, and can get more performance by its spatial structure and morphology of regulation graphene in large part to expand its applications.

Although graphene has a high mobility rate, room temperature quantum Hall effect, high thermal conductivity and high visible light transmittance, etc., which gives graphene variety of excellent physical and chemical properties, but its perfect duality symmetry also resulted in a lack of modulation of graphene space above for three-dimensional assembly of two-dimensional graphene is clearly a good idea to improve this defect, but at the same time, if you can be introduced in the graphene lattice hetero atom , thus breaking the symmetry of graphene structure increases the number of active sites and to improve the catalytic properties of graphene. In particular, the three-dimensional porous graphite carbon nitrogen polymeric material because of its structure, the nitrogen atoms to carbon atoms of a very regular staggered arrangement so that the graphite carbon nitrogen has an extremely good spatial structure and optical performance, nitrogen mixed active region generated in the structural units of carbon atoms in graphite carbon nitrogen polymeric material, can significantly increase the electrical properties of graphene reduction catalytic material, which has a wide application in the field of energy storage, electric catalysis, sensors, etc. prospect.

Contents of this paper:

First, select a soft template method, and hydrogen bubbles in soft template, by means of electrochemical deposition prepared by reduction of graphene electrode material porous three-dimensional structure, and explores the reaction time, the reaction voltage category, surfactants and concentration for structural properties of the product affected. The degree of the three-dimensional macroporous graphene material is reduced, the characterization of the catalytic conversion of the photoelectric properties and spatial structure of graphene choose to use Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and electrochemical means, and explored its electrochemical properties.

Second, the selection of a nitrogen-rich melamine precursors, select FTO conductive glass as the substrate, prepared by thermal polycondensation g-C3N4 FTO conductive polymer material on the substrate, and to explore the photochemical properties of such modified electrode.

Keywords: Soft template, hydrogen bubbles, polymeric carbon nitride, FTO, graphene, photoelectrocatalysis

目录

摘要………………………………………………………………………………………I

目录………………………………………………………………………………………Ⅳ

第一章 绪论………………………………………………………………………………1

1.1 石墨烯简介………………………………………………………………………1

1.1.1 石墨烯的结构与性质………………………………………………………1

1.1.2 石墨烯的制备方法…………………………………………………………2

1.1.3 三维石墨烯的组装…………………………………………………………4

1.1.4 石墨烯的应用………………………………………………………………5

1.2 g-C3N4简介………………………………………………………………………6

1.2.1 g-C3N4的结构与性质………………………………………………………7

1.2.2 g-C3N4的制备方法…………………………………………………………8

1.2.3 g-C3N4的应用………………………………………………………………9

1.3 常用的表征手段…………………………………………………………………9

1.4 提出问题…………………………………………………………………………10

  1. 实验部分………………………………………………………………………11

2.1 三维多孔石墨烯的组装………………………………………………………11

2.1.1 氧化石墨烯的制备(Hummer)……………………………………………11

2.1.2 三维多孔石墨烯FTO修饰电极的制备……………………………………12

2.1.3 三维石墨烯FTO修饰电极的电容性能测试………………………………12

2.1.4 大孔石墨烯电极材料电容性能的探究……………………………………13

2.2 三维石墨烯/g-C3N4修饰电极的制备…………………………………………13

2.2.1 石墨烯/g-C3N4 FTO修饰电极的制备……………………………………13

2.2.2 石墨烯/g-C3N4 FTO修饰电极的光电化学测试……………………………14

第三章 结果与讨论……………………………………………………………………15

3.1 石墨烯电极材料形貌与结构的表征………………………………………15

3.2 石墨烯电极材料制备过程及影响因素……………………………………17

3.3 不同的导电基片……………………………………………………………20

3.4 电化学性质…………………………………………………………………20

3.5 石墨态氮化碳的结构表征性质探究………………………………………21

第四章 总结与展望……………………………………………………………………23

致谢……………………………………………………………………………24

参考文献………………………………………………………………………25

第一章 绪 论

1.1 石墨烯简介

石墨烯(Graphene)是由碳元素组成的只有一层原子厚度的单层平面晶体,它一般是从混合性晶体材料石墨材料中剥离出来的。2004年,来自英国曼彻斯特大学的Andre Geim和Konstantin Novoselov两位物理学家,首次成功地从石墨中分离出了能够稳定存在的高质量的单层和多层石墨烯石墨烯材料,这引起了世界范围内的轰动。

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