Carbon Nanorods With Adhered Monodisperse Cobalt Nanoparticles Exhibiting Electromagnetic Wave Absorption and Antibacterial Potential

ABSTRACT

Magnetic particles coated with carbon shells have been considered as promising electromagnetic wave absorption materials with antibacterial features. However, how to precisely control the monodispersed magnetic nanoparticles on a carbon matrix to manipulate impedance matching and antibacterial performances is still a key challenge. In this work, we successfully prepared Co/C nanomaterials with monodispersed Co nanoparticles by thermal decomposition of rod‐like cobalt‐hexahydroxytriphenylene (Co‐HHTP) metal‐organic frameworks (MOFs). Co nanoparticles with average sizes of 11.2, 14.8, and 18.6 nm can be embedded in carbon rods after 600°C, 700°C, and 800°C annealing treatment, respectively. Small‐sized nanoparticles have an obvious effect on magnetic loss ability at high frequencies. More importantly, the dielectric feature has also been synchronously tuned by changing the annealing temperature due to the variation of the graphitization degree. The co‐regulation of dielectric and magnetic properties leads to optimal impedance matching and loss capacity and thus contributes to an effective absorption bandwidth of 5.7 GHz at 1.8 mm thickness and minimum reflection loss of −24.4 dB in Co/C‐700. Meanwhile, the rod‐like Co/C nanomaterials with monodispersed Co nanoparticles on a carbon matrix demonstrate improved antibacterial ability against sulfate‐reducing bacteria (SRB). Ulcerative colitis (UC) is closely linked to SRB and its metabolite hydrogen sulfide. The relative viability of SRB in the suspension containing 2 g L ⁻¹ Co/C‐700 decreased to 7.9%. Our work provides a novel approach to synthesize size‐controllable magnetic nanoparticles on a carbon matrix, which exhibit promising applications in the electromagnetic wave absorption (EMA) field and treatment of UC caused by SRB.