Polyvinylpyrrolidone induced uniform coating of nickel nanoparticles on carbon nanotubes for efficient microwave absorption

[Display omitted] •A facile approach of achieving uniform coating of Ni on CNTs by PVP induction was proposed.•PVP can effectively control the size of Ni particles and their distribution in CNTs.•Ni/CNTs with PVP has excellent absorbing properties including a RLmin of −39.6 dB and an EB of 5.2 GHz.•The uniform coating of Ni effectively improves the shortcomings of CNTs such as poor impedance matching performance and single form of loss. The impedance matching performance of carbon nanotubes (CNTs) can be effectively enhanced by developing a uniform magnetic impedance matching layer, which can take on critical significance in achieving the desirable microwave absorption (MA) performance. To obtain a uniform coating of Nickel (Ni) nanoparticles on CNTs, several methods have been developed (e.g., the γ-irradiation technique, electroless deposition, as well as microwave welding method). However, the intricate and complicated conditions of the above-mentioned methods limit their wide application. Therefore, controlling the distribution of Ni nanoparticles with the aid of a concise and effective method remains a great challenge. Herein, in view of the uniform dispersion effect of polyvinylpyrrolidone (PVP) on CNTs and its complexation with Ni ions, uniform coating of Ni nanoparticles on CNTs is well developed after it is introduced in the hydrothermal process. The prepared Ni/CNTs composites exhibited excellent MA performance in comparison with those of reported Ni/CNTs composites for the ideal impedance matching performance and microwave attenuation ability. When the filler content was only 15 wt%, the minimum reflection loss (RLmin) reached −39.5 dB, and the effective bandwidth (EB) with RL