An unusual route to grow carbon shell on Fe 3 O 4 microspheres with enhanced microwave absorption

Designing of cores-carbon shell composites has become a significant part because of particularly protective role for cores and stabilized chemical properties of carbon shell. Generally, two steps are needed to produce carbon shell, forming polymer precursor on cores first and calcinating subsequently. In this work, we propose a facile and novel route to develop carbon shell by means of carboxyl groups' decomposition. In detail, carboxyl groups-decorated Fe3O4 microspheres as core were prepared first through a simple hydrothermal process. Next, the as-obtained samples without further polymer coating were straight annealed at inert atmosphere to prepare Fe3O4@C core-shell microspheres, which just needed one step and could achieve uniform coating. Several of characteristic techniques demonstrated that the carboxyl groups can directly decompose into carbon matter at inert atmosphere under high temperature calcination. Besides, it is also confirmed the carbon shell played a crucial role in improving dielectric dissipated ability and microwave absorption (MA) performance of bare Fe3O4 microspheres. Not limited to excellent MA properties of Fe3O4@C microspheres, we hope this strategy could open a new avenue for other research fields to construct cores-carbon shell functional materials.