Effect of morphology and microstructure of NiCo nanoparticles on the electromagnetic shielding behavior of flexible and durable NiCo-coated carbon fibers

Carbon fibers (CFs) coated with magnetic metal nanoparticles have attracted much consideration for enhanced electronic applications. Magnetic nickel/cobalt (Ni/Co) alloys were coated on the surface of CFs (NiCo-CFs) using the electroplating process. For the first time, different NiCo alloys were attained by adjusting the various Ni²⁺ to Co²⁺ mole ratios (1:0.5, 1:1 and 1:2). The surface morphology, elemental analysis, color, microstructure, weight gain, electrical conductivity and magnetic properties of the NiCo-CFs were investigated as a function of Ni²⁺ to Co²⁺ mole ratios. The surface morphology and elemental mapping demonstrated that NiCo alloy nanoparticles are uniformly coated on the CFs surfaces. With changing the Ni²⁺ to Co²⁺ molar ratio from 1:0.5 to 1:2, the average size of particles continuously increased from 83 ± 14 to 194 ± 42 nm. Moreover, with increasing nanoparticle size, the magnetic properties of NiCo alloys significantly improved. The change of the Ni:Co molar ratio to 1: 1 improved the microstructure properties of NiCo alloy, not only raising the electrical conductivity to 571.42 ± 25.61 S/cm but also enhancing EMI shielding efficiency (SE) to − 52.7 dB. The ultra-high durability of NiCo-CFs structure was confirmed by bending deformation and high-energy ultrasonic treatments. This study has revealed the possibility of using NiCo-CFs as high-durable EMI shielding applications.