Influence of nitric acid treatment on the electrical conductivity in CNT fiber and CNT sheet

Abstract

The background of carbon nanotube (CNT) is reviewed to provide a basic understanding on CNT. Although individual CNTs possess exceptional electrical properties, the understanding of the electrical properties of their assemblies is still unclear as these properties are greatly influenced by assembly structure and the functionalization of CNTs.

In this report, two practical CNT assemblies, CNT fiber and CNT sheet, are produced and treated with nitric acid to study how the treatment influences the assembly’s structure and electrical properties. Characterization techniques such as Scanning Electron Microscope (SEM) and Raman Spectroscopy are employed to study the CNT morphological and structural properties. The electrical properties are measured based on the conductivity of the material, where the resistance and diameter of the CNT assemblies are obtained using CHI760 instrument and SEM.

For comparison, CNT fiber and CNT sheet, with and without treatment are studied and analyzed. The results show that treatment with nitric acid introduces defects and functional groups on CNTs, and thus improves the conductivity of CNT sheet. Prolong treatment with nitric acid results in more defects and drastic change in the morphology of CNT assemblies. Furthermore the intensity of D band to G band (ID/IG) ratio of CNT assemblies increases after the treatment. The relationship between functionalization and electrical properties is discussed.