Ag3PO4 nanoparticle-decorated Ni/C nanocapsules with tunable electromagnetic absorption properties

Core/shell-structured nickel/carbon (Ni/C) nanocapsules with Ag3PO4 nanoparticle decoration (Ag3PO4@Ni/C) are prepared by an arc-discharge process and an ion-exchange process. The Ag3PO4@Ni/C nanocapsules show a clear decoration of Ag3PO4 nanoparticles of 4–20 nm diameter on the C shell of the Ni/C nanocapsules of ∼60 nm diameter. The amount of Ag3PO4 nanoparticles that can be decorated on the Ni/C nanocapsules depends on the volume of Na2HPO4 reactant used in the ion-exchange process. The Ag3PO4@Ni/C nanocapsules demonstrate interestingly high and tunable electromagnetic absorption properties with different amounts of Ag3PO4 nanoparticle decoration in the paraffin-bonded composites over the 2–18 GHz microwave range. The nanocapsules prepared with 100 ml Na2HPO4 exhibit much enhanced dielectric and magnetic losses for an improved electromagnetic impedance match. These result in a large reflection loss (RL) of -31.4 dB at 12.3 GHz for a small absorber thickness of 2.6 mm in conjunction with a very wide effective absorption bandwidth (for RL<-10 dB) of 14 GHz (4–18 GHz) at a wide absorber thickness range of 1.4–5.0 mm.