Boosted Interfacial Polarization from the Multidimensional Core–Shell–Flat Heterostructure CNP@PDA@GO/rGO for Enhanced Microwave Absorption

Heterogeneous structures have attracted extensive attention in the area of microwave absorption because they can promote interfacial polarization and thus enhance microwave absorption. Many efforts have been made in this field; however, challenges remain in terms of the absorber impedance matching and electromagnetic (EM) wave reflectivity. Herein, a multidimensional core–shell–flat heterostructure is proposed to build a kind of EM wave absorbers with both dielectric loss and magnetic loss. Polydopamine (PDA) is coated on the surface of nanoscale carbonyl nickel powder (CNP) to obtain the core–shell structure of CNP@PDA nanoparticles, and then, the CNP@PDA nanoparticles are grafted around graphene oxide (GO)/reduced GO (rGO) or sandwiched between the layers of GO/rGO to form a core–shell–flat heterostructure. Two-dimensional GO/rGO and three-dimensional PDA can modulate the impedance matching of nano-CNP and enhance the interfacial polarization of the absorber. The reflection loss of ternary CNP@PDA@GO/rGO is better than that of binary CNP@PDA or CNP@GO due to the interfacial polarization and multiple interfacial scattering of the heterostructure. The minimum reflection loss can reach −70.7 dB with a thickness of 2.5 mm, while the efficient absorption bandwidth (≤−10 dB) can achieve 8.5 GHz. The heterojunction contacts constructed by CNP–PDA and PDA–GO/rGO contribute to the enhanced polarization loss and interfacial reflection loss. The mechanism of excellent EM wave absorption is explained by enhanced interfacial polarization, interface scattering, and adjusted impedance matching. These results pave the way to fabricate high-performance EM wave absorption materials with a controlled multidimensional morphology and balanced impedance matching.