Recycling waste chaff to prepare biochar with co-decorated CoCO3/CoNiO2 for anti-bacterial microwave dissipation

Abstract

In order to address the recession of absorption properties and service life in electromagnetic absorbers caused by the bacterial propagation, the design of microwave absorbing composite with excellent antimicrobial character is an urgent requirement. Herein, the grain husk-derived carbon is co-decorated with CoNiO2 and CoCO3 nanoparticles through a facile hydrothermal-carbonization process. The defect structure and graphitization in biochar, complex interfaces between multi-components, and partial magnetic resonances can be regulated with the calcination temperature. With an appropriate impedance matching from balanceable electromagnetic parameters, the C4 composite treated by 650 °C realizes an optimal electromagnetic absorption of -41.87 dB at 2.5 mm thickness with its efficient absorption bandwidth of 4.45 GHz at 1.49 mm, which is mainly owing to the powerful dielectric dissipation caused by polarization and conduction losses together. Additionally, the composite exhibits a higher antimicrobial rate of 97.75 % against ubiquitous E. coli, indicating this work provides a reference for designing antimicrobial microwave absorption materials with better practicality.