还原温度对氧化石墨烯的湿度-甲醛交叉敏感性能的影响

以氧化石墨烯溶胶为前体，通过旋涂工艺制备薄膜型气敏元件，在低温80～180℃下进行热处理，获得系列不同还原程度的还原氧化石墨烯气敏元件，采用XRD、AFM、FT-IR、XPS对样品的层结构、薄膜厚度及含氧官能团变化属性进行表征，将气敏薄膜元件在相对湿度为11.3%～93.6%的范围内进行预湿处理，并测定元件对甲醛气氛的敏感性能。结果表明：随热还原处理温度的升高，氧化石墨烯的结构逐渐向类石墨结构转变，含氧官能团逐渐脱失，缺陷增多，薄膜的方块电阻呈数量级地减小，从41 MΩ减小至928 Ω；经不同湿度预处理的气敏元件置于甲醛气氛中产生了水分子与甲醛分子的竞争吸附，从而导致电阻的明显变化；在10^?4甲醛气氛下，未还原或热还原温度较低的气敏元件适用于低、高湿环境下甲醛气氛的气敏测试，最大灵敏度为69.1%，而还原温度适中的元件则适用于中湿环境的甲醛测试，最大灵敏度为80.3%。

Influence of reduction temperature of graphene oxide on cross sensitivity between humidity and formaldehyde

As precursors, graphite oxide samples are exfoliated and used to prepare graphene oxide thin films by gas spin coating with Ag-Pd integrated electronic device (Ag-Pd IED). The graphene oxide thin films are annealed at 80—180℃ to obtain a series of reduced graphene oxide gas sensing element samples with different reduction degrees, and the layer structures, film thickness and functional groups change properties of all the samples are investigated by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, Atomic force microscope and X-ray photoelectron spectroscopy. The prehumidification treatment with the relative humidity from 11.3% to 93.6%, the gas sensitivity tests are carried out to reduced graphene oxide thin film gas sensing element. Then the formaldehyde gas sensing measurement are also implemented. The results show that the structure of the graphene oxide samples are transformed to the graphitic structure after reduction at different thermal treatment temperatures. The oxygen functional groups on the surface of graphene oxide gradually pyrolyzed, the defects increase, the structure of graphene gradually changes to similar to graphite, and the resistance of the samples were significantly reduced in magnitude with 41 MΩ to 928 Ω. The samples with different relative humidity pretreated produced competitive adsorption of water molecules and formaldehyde molecules in formaldehyde atmosphere, leading to obvious changes in resistance. When exposed to the 10^?4 formaldehyde gas at room temperature, unreduced or the reduced products at low temperature show good sensitivity of 69.1% to formaldehyde gas in high humidity environment. In medium humidity environment, the reduced products at medium temperature which exhibit a best sensitivity of 80.3% are suitable for the test of formaldehyde gas.