Protein-Derived Hybrid Carbon Nanospheres with Tunable Microwave Absorbing Performance in the X‑Band

Biomass-derived carbon absorbents are gaining increasing interest owing to their renewability, simple preparation, and unique electrical properties. However, the uncontrollability of both the composition and the morphology of the natural biomass precursor leads to inevitably poor reproducibility of the microwave absorbing (MA) performance for practical application. In this study, protein-derived hybrid carbon nanospheres (GCNs) were successfully synthesized using gelatin molecules as precursor units, and then they were mixed into resin to prepare composites with excellent MA properties. By tuning the carbonization temperature, both the crystallization degree and the elementary composition of the GCNs absorbents could be conveniently adjusted to balance various microwave attenuation mechanisms. The developed GCNs/resin composites exhibited a minimum reflection loss of −50.9 dB and effective absorption bandwidth of 3.5 GHz in the X-band. The excellent MA properties of the GCNs with tailored geometrical morphology and tunable composition provided a new inspiration for future development on biomass carbon-based microwave absorbing materials.