C/Ni/N Nanocomposites Based on Hydrolysis Lignin: Synthesis, Study of Structural and Magnetic Properties

A two-step method for the synthesis of C/Ni/N nanocomposites based on hydrolysis lignin from wood chemical processing waste is proposed. These nanocomposites were found to have a well-developed porous structure with a wide pore size distribution. It was shown that doping hydrolysis lignin with urea-derived nitrogen leads to the appearance of ferromagnetic behavior in the carbon material. When nickel chloride was added during pyrolysis, the magnetic behavior of the C/Ni/N composite was provided by superparamagnetic Ni particles less than 30 nm in size and the magnetism of the carbon matrix. The addition of urea during the synthesis of the nanocomposite further promotes better integration of nickel into the carbon structure. According to the results of magnetic studies, the nickel content in the C/Ni/N nanocomposite was 19 wt.% compared to 15 wt.% in the C/Ni nanocomposite. The synthesized nanocomposite was demonstrated to have no residual magnetization, so its particles do not agglomerate after the external magnetic field is removed. Due to this property and the well-developed porous structure, C/Ni/N composites have the potential to be used as catalysts, active electrode materials for autonomous energy sources, and in environmental technologies as magnetically sensitive adsorbents.