Using silk-derived magnetic carbon nanocomposites as highly efficient Nanozymes and electromagnetic absorbing agents

Functional carbon nanomaterials have become the stars of many active research fields, such as electronics, energy, catalysis, imaging, sensing and biomedicine. Herein, a facile and one-pot strategy for generating ferromagnetic nanoparticles loaded on N-doped carbon nanosheets (Fe-N-CNS) is presented by salt-assisted high-temperature carbonization of natural silk proteins. Due to their graphitic structures, N-doping and ferromagnetic nanoparticles (FeNx, FeOy, FeCz), the silk-derived Fe-N-CNS can act as excellent mimics of both peroxidase and oxidase. Benefiting from the combined character of the graphene-like structures and enzyme-like activities, Fe-N-CNS can be further applied to highly efficient dye removal via synergistic adsorption and degradation. Meanwhile, the as-prepared Fe-N-CNS with intrinsic magnetism and electrical conductivity can also serve as an efficient electromagnetic wave absorption agent. The broadest effective absorption bandwidth (EAB) of as-obtained absorbing material yields a 6.73 GHz with 1 mm thickness, with a maximum reflection loss of −37.33 dB (11.41 GHz). The EAB can cover 2∼18 GHz with a tunable absorber thickness from 1.0 mm to 5.0 mm. Collectively, Fe-N-CNS, as a dual-functional material, can tackle the aggravating environmental pollution issues of both dyes and electromagnetic waves.