基于电化学阳极氧化的多壁碳纳米管表面改性

Surface modification of multiwall carbon nanotubes by electrochemical anodic oxidation

分别以硫酸和氢氧化钠溶液为电解液,用阳极氧化方法对多壁碳纳米管进行表面改性处理。采用了扫描电子显微镜,透射电子显微镜,Zeta电位仪,红外光谱仪,X-射线光电子能谱仪和拉曼光谱仪等表征手段对多壁碳纳米管的形貌、分散性、功能化程度及缺陷程度等方面进行了表征。多壁碳纳米管经阳极氧化后,表面含氧官能团数量增加,这提高了其在水溶液中的分散性。但是在不同的电解液中阳极氧化后,纳米管的分散性、官能团种类和表面缺陷情况不同。在氢氧化钠溶液中阳极氧化会在纳米管表面引入更多含氧官能团,而在硫酸溶液中阳极氧化会在纳米管表面引入更多缺陷。

The surface modification of multiwall carbon nanotubes(MWCTNs)was achieved by electrochemical anodic oxidation in NaOH and H2SO4 electrolytes.Their defect structures,functional groups,morphology and dispersibility in aqueous solutions were characterized by SEM,TEM,XPS,FTIR,Raman spectroscopy,zeta potential analysis and a stability test of their suspensions.Results indicate that anodic oxidation with the NaOH electrolyte removes more amorphous carbon,introduces fewer defects and more oxygen-containing functional groups(mainly-OH),and produces shorter nanotubes,as a result of which the resulting nanotubes are more stable when dispersed in aqueous solutions compared with those oxidized by the H2SO4 electrolyte.MWCTNs are more easily oxidized in the NaOH electrolyte,and the numbers of oxygen-containing functional groups and hydroxyl groups increase continuously with the oxidation degree.In the H2SO4 electrolyte,however,the numbers of oxygen-containing functional groups and hydroxyl groups increase and level off with the oxidation degree.