基于化学修饰石墨烯传感器的研究

发布时间：2018-09-01 06:47

【摘要】：石墨烯是单原子厚度的二维晶体,具有巨大的比表面积,良好的机械力学性能,稳定的物理、化学性质和优异的室温导电性。因此,石墨烯及其复合物是研制各种传感器的理想材料。本论文系统研究了石墨烯表面电化学活性位点,制备了数种石墨烯基气体传感器和应变传感器并表征了其性能。主要内容如下:以单层石墨烯作为研究对象,选择性区域封装边缘位置和平面位置,分别得到边缘电极和平面电极,并比较了二者电化学行为的差异。边缘结构表现出比平面高出4个数量级的面积比电容量、更快的电子转移速率以及更低的电催化过电位。石墨烯的平面可提供优异的导电能力,而边缘的缺陷结构则是理想的能量存储和电催化活性材料。通过在石墨烯表面共价修饰乙二胺基制备了乙二胺石墨烯,通过预还原-修饰-再还原法制备了磺化石墨烯。通过简单的浸涂技术分别将这两种石墨烯材料组装成超薄膜作为化学电阻型气体传感器的活性层。该传感器可选择性地检测二氧化氮气体;与单纯的石墨烯相比,其检测灵敏度有大幅度提高。在较宽的二氧化氮浓度范围内,两种传感器的响应信号都与气体浓度之间表现出良好的线性关系,具有良好的重现性和选择性,并可通过氮气吹扫实现二氧化氮气体可逆脱附。通过静电纺丝技术制备了聚乙烯亚胺/聚乙烯醇复合纤维,表面组装小尺寸单层石墨烯,得到石墨烯/聚合物复合纤维并将其直接应用于电阻型二氧化氮气体传感器。该传感器可在室温条件下使用,灵敏度可达1.03 ppm-1,实验检测限为150ppb,并具有良好的选择性和循环可逆性。响应和恢复速度也有较大幅度的提升。利用可再生资源头发作为弹性体,表面组装氧化石墨烯,通过进一步还原得到还原石墨烯/头发复合纤维并将其应用于应力传感器。该传感器超小超轻并具有良好的强度。由于基底材料具有良好的柔性和可塑性,传感器可以为纤维、弹簧、也可编织成网络结构。可用于检测拉伸、弯曲、压缩等不同应力形变,作为可穿戴设备的一部分可用于手指弯曲的传感,作为压力开关可检测手指轻点的微小压力。
[Abstract]:Graphene is a two-dimensional crystal with single atomic thickness. It has a large specific surface area, good mechanical and mechanical properties, stable physical and chemical properties and excellent conductivity at room temperature. Therefore, graphene and its complex are ideal materials for the development of various sensors. In this paper, the electrochemical active sites of graphene surface were systematically studied. Several graphene based gas sensors and strain sensors were prepared and their properties were characterized. The main contents are as follows: taking graphene monolayer as the research object, the edge electrode and the planar electrode were obtained respectively at the edge position and the plane position of the selective region encapsulation, and the difference of electrochemical behavior between them was compared. The edge structure shows four orders of magnitude higher area specific capacitance, faster electron transfer rate and lower electrocatalytic overpotential than the plane. The plane of graphene can provide excellent conductivity, while the defect structure at the edge is an ideal material for energy storage and electrocatalytic activity. Ethylenediamine graphene was prepared by covalent modification of ethylenediamine group on the surface of graphene, and sulfonated graphene was prepared by pre-reduction-modification-rereduction method. The two graphene materials were assembled into ultrathin film as the active layer of chemical resistive gas sensor by simple impregnation technique. The sensor can selectively detect nitrogen dioxide gas, and the sensitivity of the sensor is much higher than that of graphene alone. In a wide range of nitrogen dioxide concentrations, the response signals of the two sensors show a good linear relationship with the concentration of the gas, with good reproducibility and selectivity, and the reversible desorption of nitrogen dioxide gas can be realized by nitrogen gas blowing. Poly (ethyleneimine) / polyvinyl alcohol (PVA) composite fibers were prepared by electrospinning technique. The graphene / polymer composite fibers were fabricated on the surface of monolayer graphene and directly applied to the resistive nitrogen dioxide gas sensor. The sensor can be used at room temperature. The sensitivity of the sensor is up to 150ppb. The sensor has good selectivity and cyclic reversibility. Response and recovery speed has also been greatly improved. Using renewable hair as elastomer, graphene oxide was assembled on the surface, and the reduced graphene / hair composite fiber was obtained by further reduction and applied to the stress sensor. The sensor is super small and light and has good strength. Because the substrate material has good flexibility and plasticity, the sensor can be fiber, spring, or woven into a network structure. As a part of wearable device, it can be used as a sensor of finger bending, and as a pressure switch, it can be used to detect the tiny pressure of finger light point.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ127.11;TP212

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