Hybrid composite materials generated via growth of carbon nanotubes in expanded graphite pores using a microwave technique

Abstract

Herein we demonstrate a facile in-situ synthesis method by selection of expanded graphite as a matrix growth microreactor, nickel nitrate (Ni(NO3)2) as a growth catalyst and naphthalene as a carbon source, assisted by a conventional household microwave oven. Affection parameters related to control of the growth process, such as the microwave heating time, catalyst concentration and carbon source concentration. The optimized experimental conditions that exhibit excellent microstructure were: a carbon source concentration of 20.0 mg/ml, a catalyst concentration of 10.0 mg/ml and a microwave reaction time of 30 s. The microstructure of the synthesized composites was investigated and a solid-gas growth mechanism with this carbon source precursor is proposed. The micro morphology, formed CNT structure and resistivity of the composites are fully characterized and analyzed by thermal field emission high-resolution scanning electron microscopy (FESEM), confocal laser Raman spectrometer (Raman) and a four-point probe resistivity meter. All characterization data show a uniform CNT diameter distribution of approximately 30.0 nm with a low resistivity of the composites (1.12 × 10−5 Ω·m), indicating uniform hybrid composite material formation with novel physical properties.