Surface modification of multiwalled carbon nanotubes network through high energy electron beam and its implications on thermoelectric properties

In this work we demonstrate the surface modifications in free standing network of multi walled carbon nanotubes (MWCNTs) upon irradiation with 10 MeV electron beam. The irradiated samples initially showed an electrical conductivity enhancement along with keeping almost constant Seebeck coefficient up to dose of 50 kGy. At higher dose levels (>50 kGy) the electrical conductivity starts decreasing. In depth characterization of irrdaited MWCNT sheet samples using Raman spectroscopy, x-ray photoelectron spectroscopy, thermogravimetric studies and morphological analysis revealed that the impact of high energy electron beam on MWCNT creates C-O types of defects which induces a p-type doping in MWCNT. However at higher dose these defects starts annihilating. So the present work demonstrates the high energy electron beam is an alternative to modify the thermoelectric properties of MWCNTs owing to defect engineering.