DEVELOPMENT OF COBALT OXIDE AND HIERARCHICALLY POROUS ACTIVATED CARBON COMPOSITES FOR MICROWAVE ABSORPTION AT XBAND FREQUENCY

Electromagnetic interference (EMI) affects the proper functioning of electronic
devices due to the advances in electronic devices, and excessive exposure to EM
radiation endangers human health. Microwave absorption has emerged as an innovative
application area where nanomaterials can tackle EMI due to their intrinsic dielectric
and magnetic properties. Thus, this study involves fabricating novel microwave
absorbing materials (MAMs) from Co3O4 and porous activated carbon (PAC) obtained
from banana peel. In this study, porous activated carbon (PAC) was derived from
banana peel via chemical activation and carbonization at different temperatures. Then,
Spinel cobalt oxide (Co3O4) nanoparticles and Co3O4@PAC composites were prepared
using the facile hydrothermal method. The samples' thermal stability, phase
crystallinity, chemical composition, surface morphology, and porosity were studied
using TGA, XRD, FTIR, XPS, FESEM, and SAP characterization techniques,
respectively. The FESEM result reveals the formation of a unique cornale like flower
structure. The samples' microwave absorption properties (MAP) at 30 wt% loadings
were studied at X band (8.2 - 12.4GHz) frequency. A Co3O4@PAC700 composites
display enhanced microwave absorption performance with a minimum RL value of -
44.50dB at 10.84 GHz with an adequate absorption bandwidth of 1.08 GHz at 2.0 mm
absorber thickness. The unique flower-like morphology of the composites with good
porosity would favour EM wave scattering and multiple reflections of EM wave,
thereby resulting in high attenuation of the EM wave. The flower-like morphology
prolongs the electromagnetic wave propagation path, favoring gradual attenuation of
electromagnetic waves. This work suggests that the Co3O4@PAC composites can be
considered a good absorber for EM absorption application. This study provides a new
path to designing novel magnetic and dielectric composites for effective microwave
absorption.