Facile synthesis of ultra-lightweight Ni/NiO/NixPy foams with hollow sandwich micro-tubes for absorption-dominated electromagnetic interference shielding

Absorption-dominated electromagnetic interference (EMI) shielding materials could effectively minimize secondary pollution in the shielding process, which is of great significance in practical applications. Herein, we propose a facile one-step thermal treatment strategy to prepare lightweight Ni/NiO/NixPy foams with a hollow sandwich micro-structure and an absorption-dominated excellent EMI shielding effectiveness (SE). Due to the transformation of the Ni-P alloy coating created by chemical deposition during the heat treatment, the conductivity of Ni/NiO/NixPy micro-tubes decreases from 5.85 x 10(3) S/m to 3.32 x 10(-4) S/m, while its magnetization varies from 0.67 emu/g to 9.39 emu/g with fluctuation. The EMI SE of the foams reaches 41.34 dB at a mere density of 70 mg/cm(3) and the normalized specific SE is up to 2261.0 dB cm(2)/g with an ultra-low density of 35 mg/cm(3). The synergy of hollow micro-tubes and multi-interface results in high absorption coefficients (above 0.5) of the Ni/NiO/NixPy foams. This work provides a new idea for the preparation of EMI shielding materials with high absorption, low density, and tunable electromagnetic properties.