不同氧化程度氧化石墨烯氨气敏感性能及机理

Sensitivity and mechanism of graphene oxide with different oxidation degree to ammonia

摘要:

采用改进Hummers法制备的不同含氧官能团占优的氧化石墨(GO)，经超声分散制备不同含氧官能团占优的氧化石墨烯(GOs)，采用旋涂法制备厚度均一的氧化石墨烯气敏膜。利用XRD、FT-IR、XPS等现代分析测试手段对氧化石墨（烯）样品的结构、官能团的种类及含量进行分析；利用WS-30A气敏测试系统对氧化石墨烯气敏元件的氨气(NH3)敏感性能进行测试。结果表明：氧化石墨后含有羟基(-OH)、环氧基(C-O-C)等含氧官能团，面网间距最大达到0.935 nm；随氧化程度的增加，元件的初始电阻由550 KΩ增加至2500 KΩ；不同GOs气敏元件对NH3灵敏度与其羟基(C-OH)的相对含量呈正相关关系，GOs中羟基相对含量为43.75%时，气敏元件对80 ppm的NH3的最大灵敏度达到78%，响应时间为37 s，且有较好的稳定性和重复性，重复性误差为3.1%。GOs对NH3分子的响应存在NH3分子进入GOs片层间水分子层后水解形成NH4 的离子电导和GOs结构层上含氧官能团对NH3分子吸附后形成氢键的电荷转移两种机制。

Abstract:

Graphene oxide (GO) with different oxygen-containing functional groups was prepared by improved Hummers method, then ultrasonic dispersion. And the graphene oxide film prepared by spin coating method. The type and content of the functional groups, spectral characteristic were implemented by XRD, FT-IR, XPS. Ammonia(NH3) sensitivity is tested by WS-30A gas sensing system. The result shows that graphite oxide contains oxygen functional groups such as hydroxyl group (C-OH), epoxy group (C-O-C) and so on, the maximum spacing of surface network reaches 0.935 nm；with the oxidation degree increases, the initial resistance of the component increases from 550 KΩ to 2500 KΩ. The sensitivity of different GOs gas sensors to NH3 is positively correlated with the relative content of hydroxyl group. When the relative content of hydroxyl group in GOs is 43.75%, the maximum sensitivity of gas sensor to 80 ppm NH3 is up to 78%, and the response time is 37 s, and the gas sensor exhibits good stability and repeatability, the minimum error of repeatability is 3.1%. There are two mechanisms for the response of GOs to NH3 molecules: the ionic conductance mechanism of NH3 molecules entering GOs interlayer water molecules after hydrolysis to form NH4 ions; the charge transfer mechanism of hydrogen bonds formed by oxygen functional groups on the GOs structure layer after adsorbing NH3 molecules.