3D graphene decorated with nickel nanoparticles: in situ synthesis, enhanced dispersibility, and absorption-dominated electromagnetic interference shielding

The synergization of 3D graphene with magnetic nanoparticles provides effective strategies to shield electromagnetic waves. However, the uniform distribution of magnetic nanoparticles within the 3D graphene network still remains a great challenge, owing to the agglomeration tendency of the magnetic nanoparticles. Herein, we report a facile method to in situ fabricate 3D graphene decorated with highly dispersed nickel nanoparticles (Ni NPs) by laser conversion from the polyimide/Ni(II) precursor film. In this process, 3D graphene was generated by CO2 laser scribing of the polyimide film, accompanied by carbothermal reduction of Ni(II) to form Ni NPs. Significantly, in the precursor film, carboxylate ions were introduced to complex with Ni(II), leading to a uniform dispersion of Ni(II), thus Ni NPs with high dispersibility in 3D graphene networks were achieved after laser fabrication. As a result, massive heterogeneous interfaces and dense magnetic coupling networks were realized in the graphene/Ni composite, which is conducive to improving polarization loss and magnetic loss for the dissipation of incident electromagnetic waves. Combined with the multiple electromagnetic wave dissipation paths provided by 3D graphene, the graphene/Ni composite exhibits absorption-dominated electromagnetic interference shielding effectiveness (EMI SE). At an Ni content of 5.3 wt%, the EMI SE of the double-layer graphene/Ni composite was 94 dB with an adsorption ratio of 91% in the X-band. Such a high EMI SE value will pave the way for practical applications of 3D graphene in EMI shielding.