碳纳米管负载纳米Fe_2O_3的研究

Nanoferric Oxide Supported on Carbon Nanotubes

本文研究了用液相化学沉积法制备的碳纳米管负载Fe2O3。首先用浓HCl、浓HNO3和浓HNO3/H2SO4(混酸)三种酸对碳纳米管进行改性处理,对样品进行了TEM形貌观察和FTIR光谱分析,FTIR分析表明浓HCl处理后不能在碳纳米管表面引入官能团,而浓HNO3能在碳纳米管表面引入-OH和-C=O,浓HNOO3/H2SO4能在碳纳米管表面引入大量的-OH、-C=O、COOH。制备了以上三种碳纳米管分别负载Fe2O3。TEM分析表明,负载效果:混酸>浓HNO3>浓HCl。经混酸处理后的碳纳米管所负载的Fe2O3的XRD分析,表明所负载的是α-Fe2O3。机理分析表明碳纳米管上的含氧基团能增强其在水溶液中的分散性,同时能增强其对Fe3+吸附和离子交换能力,使吸附在碳纳米管表面的Fe3+成为结晶成核中心,调节溶液pH值后,使Fe2O3沉积在碳纳米管表面。

Fe2O3 nanoparticles supported on modified carbon nanotubes （CNTs） were prepared by Liquid-diposition process. CNTs were functionalized by cocentreated HCl, concentrated HNO3 and mixed concentrated HNO3/ H2SO4, respectively. The concentreated HCl could only remove the metal impurities from the CNTs, but could not produce any fuctional groups on the CNTs′ surface, concentrated HNO3 could produce functional groups such as： -OH, -C=O on the surface of CNTs and concentrated HNO3/H2SO4 showed a higher capability to produce a high density of fuctional groups of -OH, -C=O, COOH as evidenced by FFIR results. Fe2O3 deposited on these three kinds of CNTs. The TEM results showed that Fe2O3 could be differently deposited on the external surface of CNTs treated with these concentrated acids. The deposition could form a layer of Fe2O3 film on the external surface of CNTs treated by concentrated HNO3/H2SO4. Among the three CNTs, the one treated by concentrated HNO3/H2SO4 was the best support media, followed by the CNTs treated by concentrated HNO3. The support capacity of CNTs treated with concentrated HCl was the worst. The XRD pattern of the Fe2O3 film coated on CNTs treated with concentrated HNO3/H2SO4 revealed that the coating was α-Fe2O3. The dispersion of CNTs in aqueous solutions could be enhanced by functional groups and thus the CNTs′ capacity for adsorpting Fe^3＋ ions and ion exchange was well improved. The Fe^3＋ adsorbed on CNTs＇ external surface acted as specific nucleation sites for a well dispersed deposition of Fe2O3 cluster.