Combination of pumpkin-derived biochar with nickel ferrite/FeNi₃ toward low frequency electromagnetic absorption

The rapid development of electromagnetic communication and electronic technique has brought serious problems of EMI and electromagnetic radiation. Herein, a combined method of ball milling, hydrothermal and multiple calcination processes was utilized to synthesize pumpkin-derived biochar/nickel ferrite/FeNi₃ composite. The nickel ferrite and FeNi₃ nanoparticles are distributed uniformly on the surface of biochar, and the thin carbon layer formed on the surface of NPs endows a better impedance matching to the particles. The excellent low frequency absorption performance can be achieved via the cooperative effect of dielectric and magnetic wastage mechanisms i.e., low frequency natural resonance, abundant interface polarization, dipolar polarization, conductive loss, multi-reflection and scatter etc. The maximum RL value achieves − 59.29 dB at 1.30 GHz with the effective absorption bandwidth of 1.34 GHz (0.76–2.1 GHz), declaring this biochar/nickel ferrite/FeNi₃ ternary hybrid could be used as one kind of efficient low frequency electromagnetic absorbent.