还原温度对氧化石墨官能团、结构及湿敏性能的影响

Influence of Reduction Temperature on Functional Groups,Structures and Humidity Sensitivity of Graphite Oxide

基于氧化石墨具有多种官能团，研究了还原温度对氧化石墨结构及湿敏性能的影响。在不同温度下，对改进Hummers法制备的高氧化程度氧化石墨薄膜进行了还原，制备了不同温度条件下还原的氧化石墨薄膜湿敏元件。采用FTIR、XRD和Raman对实验样品的官能团及结构变化属性进行表征分析。结果表明：石墨被氧化后，碳原子结构层上接入-OH、环氧基、C=0和COOH官能团，底面间距增大至0．9084nm；利用热还原法制备石墨烯的过程中，随着还原温度的升高，氧化石墨官能团逐渐热解．石墨化区域逐渐恢复但其相对尺寸减小．缺陷增多．氧化石墨的底面间距沿C轴方向由0．9084nm逐渐减小到0．4501nm：且不同温度还原的氧化石墨薄膜的电阻从10.32MΩ减小至41．1Ω。在11.3％～93．6％相对湿度范围内．不同温度还原的氧化石墨薄膜湿敏元件的电阻随湿度升高而显著减小；氧化石墨还原程度越高，响应时间越长，脱附时间越短；150℃还原的氧化石墨薄膜湿敏元件具有最佳的湿敏性能．

Based on the various functional groups of graphite oxide, the influence of reduction temperature on structures and humidity sensitivity of graphite oxide has been studied. High oxidized graphene oxide samples prepared by modified Hummers method were reduced at different temperature. And the humidity sensors were made with the reduction products. Functional groups and structures changes of the experiment process samples were carried out by FTIR, XRD and Raman spectrum. The results show that functional groups of -OH, epoxy group, C=O and COOH were combined with the structure layer of carbon atoms during oxidation process. And the basal spacing of graphite oxide is about 0.908 4 nm. As the increase of reduction temperature, functional groups were gradually thermal decomposition and the graphitization area gradually restored, but the relative sizes were decreased and the defects were increased. Furthermore, the basal spacing of graphite oxide was decreased from 0.908 4 nm to 0.450 1 nm along the c axis. The resistances of the graphite oxide thin film were decreased from 10.32 MΩ to 41.1 Ω. In the relative humidity of 11.3%-93.6%, the resistance of the graphite oxide thin film humidity elements was significantly reduced with increasing of humidity. The higher of the reduction degree was, the longer of element＇s response time was and the shorter of the element＇s desorption time was. The graphite oxide film humidity element of 150℃ reduction was the best humidity sensitive performance.