水合肼还原的氧化石墨烯吸附NO2的实验研究

Adsorption of NO2 by hydrazine hydrate-reduced graphene oxide

还原氧化石墨烯由于独特的原子结构,作为气体检测领域有潜力的候选者引起了研究者们的广泛兴趣.本文采用水合肼作为还原剂来制备还原氧化石墨烯,并以此作为叉指电极的气体敏感层,研究了其对NO2气体的响应特性.结果表明,水合肼还原的氧化石墨烯可以实现在室温下对浓度为1—40 ppm (1 ppm=10–6)的NO2气体的检测,具有较好的响应性和重复性,恢复率可以达到71%以上,但是灵敏度只有0.00201 ppm–1,还有较大的提升空间.此外,对浓度5 ppm的NO2的响应和恢复时间分别是319 s和776 s.水合肼还原的氧化石墨烯气体传感器的传感机制可归因于NO2分子和传感材料之间的电荷转移.还原氧化石墨烯的突出电学特性促进了电子转移过程,这使得传感器在室温下表现出优异的气体传感性能.本实验研究可为石墨烯基传感器件的应用奠定一定的基础.

Reduced graphene oxide,as a candidate for gas detection due to its unique atomic structure,is arousing the wide interest of researchers.In this paper,hydrazine hydrate is used to reduce graphene oxide prepared by the modified Hummers method.A chemical resistance gas sensor is fabricated.The prepared reduced graphene oxide is used as a gas sensitive layer of Au planar interdigital electrode.The gas sensing characteristics such as responsivity,recovery and repeatability of NO2 gas are studied.The results show that the graphene oxide reduced by hydrazine hydrate can detect the NO2 gas at a concentration of 1-40 ppm under room temperature.It has good responsivity and repeatability.The recovery rate can reach more than 71%.However,the sensitivity is only 0.00201 ppm–1,and there is much room for improvement.In addition,the response time and recovery time for NO2 at 5 ppm concentration are 319 s and 776 s,respectively.The sensing mechanism of the hydrazine hydrate-reduced graphene oxide gas sensor can be attributed to charge transfer between the NO2 molecule and the sensing material.The outstanding electrical properties of the reduced graphene oxide promote the electron transfer process.This allows the sensor to exhibit excellent gas sensing performance at room temperature.The reduced graphene oxide appears as a typical p-type semiconductor and the oxidizing gas NO2 acts as an electron acceptor.Therefore,the adsorption of NO2 gas leads to the enhancement of the hole density and conductivity of the reduced graphene oxide.Another reason is the presence of defects and oxygen-containing functional groups on graphene sheets.Some oxygen-containing groups remain on the graphene surface after an incomplete reduction reaction.Compared with pure graphene,the reduced graphene oxide has hydroxyl groups and epoxy groups remaining on the surface.These functional groups will functionalize the material and promote the adsorption of gases.At the same time,the reduction reaction will further produce vacancies and structural defects.This will provide more reaction sites and thus conduce to the material further adsorbing the gas.In summary,the experimental research in this paper is of significance for studying the mechanism and characteristics of the reduced graphene oxide by using hydrazine hydrate as a reducing agent,and it can provide reference and lay a foundation for the applications of future graphene sensors.