Facile synthesis of net-like Fe3O4/MWCNTs decorated by SnO2 nanoparticles as a highly efficient microwave absorber

Abstract

Net-like SnO₂/Fe₃O₄/MWCNTs were prepared through a simple two-step hydrothermal process. The as-synthesized composites were characterized by X-ray diffraction, vibrating sample magnetometer, transmission electron microscopy (TEM), and vector network analyses. In the process of Fe₃O₄ ripening, Fe₃O₄ particles play a role of bridge to connect MWCNTs to form a real net-like structure. TEM images indicate that Fe₃O₄ microspheres have size ranging from 100 to 200 nm, which can be seen as a scaffold for binding MWCNTs. The electromagnetic parameter results show that SnO₂ nanocrystals were introduced into the system for tuning the parameters of SnO₂/Fe₃O₄/MWCNTs composites to improve impedance match and SnO₂ nanocrystals can supply space charge and interfacial polarization. The SnO₂/Fe₃O₄/MWCNTs composites exhibit highly efficient microwave absorption capacity within the tested frequency range (2–18 GHz). The optimal reflection loss of electromagnetic waves is −42.0 dB at 10.9 GHz with an absorber thickness of 1.9 mm. The composites are potential excellent microwave absorbers with a special net-like structure for synergistic interaction between Fe₃O₄ microspheres with MWCNTs and semiconductors for tuning of electromagnetic parameters. The fabricated SnO₂/Fe₃O₄/MWCNTs composites are promising materials for high-performance microwave absorption and satisfy the highly efficient absorption capability, thin thickness, and light weight requirements for electromagnetic absorption.