Facile Fabrication of Extremely Small CoNi/C Core/Shell Nanoparticles for Efficient Microwave Absorber

Abstract

CoNi magnetic nanoparticles (NPs) and hybrid architectures have attracted tremendous attention from numerous applications. In this study, a facile approach based on one-step metal-organic chemical vapor deposition (MOCVD) was developed to fabricate CoNi/C core/shell NPs with an extremely small core size of [Formula: see text]3.7[Formula: see text]nm and an ultrathin shell thickness of 1–3[Formula: see text]nm. Only 10[Formula: see text]wt.% CoNi/C core/shell NP-filled composites with thickness of 1.6[Formula: see text]mm exhibit an optimal reflection loss value of [Formula: see text]25.7[Formula: see text]dB and an absorbing bandwidth value up to 6.2[Formula: see text]GHz. The extremely small core/shell NPs are demonstrated to have enhanced electromagnetic parameters (i.e., complex permittivity and permeability), reflection loss and broadened effective absorption bandwidth, as compared to the relatively larger NPs. The superior microwave absorbing performance should be attributed to the increased specific area with enriched interfacial polarization. The as-synthesized extremely small CoNi/C core/shell NPs are expected to be a fascinating candidate for efficient microwave absorption material with lightweight and thin thickness.