Abstract: Synthesizing multi-component composites via a straightforward, reliable, and scalable approach has been challenging. Herein, a three-dimensional nitrogen-doped porous carbon decorated with core-shell Ni₃Sn₂@carbon particles (3D N-PC/Ni₃Sn₂@C) was customized through a simple salt-template pyrolysis approach. The formed Ni₃Sn₂ particles are perfectly surrounded by crystalline carbon layers and embedded in 3D carbon walls during pyrolysis. The dual protection of crystalline carbon layers and porous carbon walls guarantees the electrical conductivity and stability of Ni₃Sn₂. The intriguing 3D and core-shell structure coupled with the introduction of multiple components empowers the composite with rich heterogeneous interface and conductive network, and contributes to the lightweight, corrosion resistance, oxidation resistance, and superior stability of electromagnetic (EM) wave absorbers. The N-PC/Ni₃Sn₂@C possesses the minimum reflection loss (RL_min) of -54.01 dB and wide effective absorption bandwidth (EAB) of 7.36 GHz under a low filler content of less than 10%. The concept in the work proposes a facile, eco-friendly, and scalable pathway for the synthesis of other heterogeneous structures of EM wave absorbers.

Key words: Nitrogen doping, Ni₃Sn₂, 3D conductivity network, Microwave absorption, Ultra-low filler loading