（氧化）石墨烯基复合材料的制备及其在传感器领域的应用

发布时间：2018-09-04 08:34

【摘要】：以改进的Hummers法制备氧化石墨,超声分散制备了氧化石墨烯(GO)水相分散液并物理涂覆于湿敏衬底制备GO湿敏元件,对其进行了FTIR表征,考察了膜厚度对其湿敏性能的影响,研究了元件的湿滞特性、响应-恢复特性、感湿机理及不同还原程度氧化石墨烯感湿性能。GO在中高湿范围内有一定的感湿特性,但存在湿滞大,低湿范围内不呈线性的问题;不同程度还原GO元件的湿滞和感湿特性曲线的线性度得到一定程度的改善,但元件的灵敏度仍需改善和提高。为提高GO感湿性能,改善线性度,采用涂覆法及共混法制备氧化石墨烯/钒钛酸复合材料,考察了涂覆顺序、膜厚度、浓度对复合薄膜湿敏性能的影响,对其感湿机理进行研究。结果表明:GO-VTi混合膜的湿滞比GO湿敏膜降低3.84%RH,元件响应时间为5s,恢复时间为8s,曲线线性度良好。VTi湿敏材料的加入对GO低湿环境中感湿特性曲线线性度有了很好的改善,但复合膜灵敏度有待进一步提高。为了提高GO复合材料的灵敏度,分别采用化学法和原位聚合法制备氧化石墨烯/聚苯胺复合材料,对聚苯胺纤维进行了SEM表征并对复合膜进行了感湿性能测试,结果表明RGO/PANI湿敏膜在全湿范围内线性度较好,量程合适,电阻随湿度变化达到3个数量级,湿滞回差约为3.81%RH,响应时间约为8s,恢复时间约为10s,与上述的单一湿敏膜及复合材料湿敏膜相比,湿敏性能有明显的改善和提高,且制备工艺简单、绿色环保、重复性好。本文通过原位聚合制备了石墨烯修饰电极,通过FTIR和交流复阻抗对其进行了表征,并测试了其对不同浓度的抗坏血酸的电催化性能及动力学参数,结果表明氧化峰电流随抗坏血酸浓度增大而增大,两者成线性关系,最低检出限为6×10-6mol/L;抗坏血酸的电化学氧化是单电子转移的反应,抗坏血酸电催化氧化反应的速率常数k0=3.78×10-6cm2/s,扩散系数D=3.24×10-6 cm2/s。实验结果表明了RGO作为电化学传感器修饰电极材料的可行性,为拓宽其在电化学传感器领域的应用提供了理论依据。
[Abstract]:Graphite oxide was prepared by improved Hummers method. The aqueous dispersion of graphene oxide (GO) was prepared by ultrasonic dispersion. The GO humidity sensor was prepared by physical coating on humidity sensitive substrate. The effect of film thickness on its humidity sensitivity was investigated. The humidity hysteretic property, response-recovery characteristic, humidity sensing mechanism and humidity sensing property of graphene oxide with different reduction degree. Go have certain humidity sensitivity in medium and high humidity range, but there is the problem of large humidity lag and no linearity in low humidity range. The linearity of hysteretic and hygroscopic curves of GO elements is improved to a certain extent, but the sensitivity of the components still needs to be improved and improved. In order to improve the humidity sensitivity and linearity of GO, graphene oxide / vanadium titanate composites were prepared by coating and blending methods. The effects of coating sequence, film thickness and concentration on the humidity sensitivity of composite films were investigated. The mechanism of humidity sensitivity was studied. The results show that the humidity lag of the mixed film is 3.84 RH lower than that of the GO humidity sensitive film, the response time of the element is 5 s, the recovery time is 8 s, and the linearity of the curve is good. The addition of VTi humidity sensing material can improve the linearity of the humidity sensing curve in the low humidity environment of GO. However, the sensitivity of the composite membrane needs to be further improved. In order to improve the sensitivity of GO composites, graphene oxide / Polyaniline composites were prepared by chemical method and in situ polymerization respectively. Polyaniline fibers were characterized by SEM and the moisture sensitivity of the composite films was tested. The results show that the RGO/PANI humidity sensitive film has a good linearity and a suitable measuring range in the whole wet range, and the resistance varies by 3 orders of magnitude with the humidity. The hysteretic hysteresis coefficient is about 3.81 RH, the response time is about 8 s, and the recovery time is about 10 s. Compared with the single humidity sensitive film and the composite humidity sensitive film, the humidity sensitive property is obviously improved and improved, and the preparation process is simple, green and environmental friendly, and the repeatability is good. Graphene modified electrode was prepared by in-situ polymerization and characterized by FTIR and AC complex impedance. The electrocatalytic properties and kinetic parameters of graphene modified electrode for ascorbic acid with different concentrations were tested. The results show that the oxidation peak current increases with the increase of ascorbic acid concentration, and the lowest detection limit is 6 脳 10 ~ (-6) mol / L, and the electrochemical oxidation of ascorbic acid is a single electron transfer reaction. The rate constant of ascorbic acid electrocatalytic oxidation is 3.78 脳 10 ~ (-6) cm ~ (-2) / s, and the diffusion coefficient is 3.24 脳 10 ~ (-6) cm2/s.. The experimental results show the feasibility of RGO as a modified electrode material for electrochemical sensors, which provides a theoretical basis for broadening its application in the field of electrochemical sensors.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332;TP212

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