Excellent microwave absorption of void@carbon@TiO2 cubes by a template sol method

Abstract

The ingenious design of heterogeneous structures is an effective strategy for developing advanced microwave absorption materials. In this study, high-efficiency void@carbon@TiO2 (void@C@TiO2) cubes were synthesized by a template sol method. Compared with void@carbon (void@C) and void@TiO2 cubes, the void@C@TiO2 cubes/paraffin composites of 2.1 µm edge length show excellent microwave absorption performances (MAPs). When the thickness is 2.1 mm, the minimum reflection loss (RL) of – 69.8 dB is superior to – 31.5 dB of void@C cubes at 4.1 mm and – 3.1 dB of void@TiO2 cubes at 3.7 mm. The effective absorption frequency covers 11.8 GHz (6.2–18.0 GHz, RL below – 10 dB) by matching the coating thickness with 1.7–5.0 mm. The enhanced MAPs originated from the synergistic processes of good impedance matching (|Zin/Z0|) and various microwave dissipation mechanisms, including electrical conduction, interfacial charge accumulation, and defect dipolar polarization. The void@C@TiO2 cubes are a lightweight, easy, environment-friendly, and extendible strategy for microwave absorption applications.