Structure and morphology of carbon nano-tubes formed on Ni and Fe−impregnated sawdust biochar during methane pyrolysis

Abstract

This study investigates the structure and morphology of nanotubes formed during methane pyrolysis (MP) over Fe and Ni impregnated sawdust biochar using Raman spectroscopy and high resolution transmission electron microscopy (HRTEM) analyses. Carbon based catalyst supports have been in focus for their synergistic effect on catalytic performances for various purposes. The carbon nanotubes (CNTs) formed during methane pyrolysis offset the cost of this process and have multiple uses. In this study, CNTs from three different temperatures with two catalysts were analysed and characterized. The CNTs were separated using ultrasonication. Lower temperature (700 °C) was not found very suitable for formation of highly graphitic CNTs for both catalysts. Multi-walled carbon nano-tubes (MWCNTs) were found to form in different degrees with both catalysts. In terms of quality of MWCNTs, Ni was found better than Fe when considered the thickness and smoothness of wall of MWCNTs. However, higher degree of graphitization and lesser identified defects were found in Fe based MWCNTs as indicated by Raman spectra. Whereas, the morphology of MWCNTs analysed by HRTEM was found at par in both catalysts. © 2025 Hydrogen Energy Publications LLC