Hydrogen storage in boron-doped carbon nanotubes: Effect of dopant concentration

Boron-doped carbon nanotubes (BCNTs) with varying B content (0-8 at%) were prepared by thermo-catalytic decomposition of ethanol in presence of boric acid at 1073 K. It was observed that hydrogen adsorption capacity improved to a critical B content of 3.86 at% and then decreased. Maximum hydrogen adsorption was found to be 0.497 wt% at 273 K and 16 bar with 3.86 at% of boron doping in CNTs. With the help of transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy, it was found that in addition to dopant concentration, dopant bonding with carbon structures, crystallinity and defects play pivotal roles in determining the extent of hydrogen adsorption by BCNTs. The thermogravimetric studies revealed the oxidation stability of the BCNTs. The hydrogen adsorption kinetics was found to follow the pseudo-second-order model. The rate constant value was minimum for the BCNT with the highest hydrogen storage capacity. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Boron-doped carbon nanotubes (BCNTs) with varying boron content were prepared by thermo-catalytic decomposition of ethanol in the presence of boric acid. Hydrogen adsorption capacity was found to improve up to a critical boron content, after which it decreased. Various factors such as dopant concentration, bonding with carbon structures, crystallinity, and defects play pivotal roles in determining the extent of hydrogen adsorption by BCNTs.