Abstract
Amorphous structures may play important roles in achieving highly efficient microwave absorption performance due to the polarization losses induced by the disorders, vacancies and other functional groups existed in them. Herein, a kind of amorphous TiO2/rGO composite (a-TiO2/rGO) was successfully fabricated via a facile one-step solvothermal method. The complex permittivity of the composites can be regulated by adjusting the addition of precursor solution. The minimum reflection loss of a-TiO2/rGO composites reached −42.8 dB at 8.72 GHz with a thickness of 3.25 mm, and the widest efficient absorption bandwidth (EAB) was up to 6.2 GHz (11.8 to 18 GHz) with a thickness of only 2.15 mm, which achieved the full absorption in Ku band (12 to 18 GHz). Furthermore, the EAB was achieved ranging from 3.97 to 18 GHz by adjusting the thickness of the absorber, covering 87.7% of the whole radar frequency band. It is considered that the well-matched impedance, various polarization processes, capacitor-like structure and conductive networks all contributed to the excellent microwave absorption of a-TiO2/rGO. This study provides reference on constructing amorphous structures for future microwave absorber researches and the as-prepared a-TiO2/rGO composites also have great potential owing to its facile synthesis and highly efficient microwave absorption.
Highlights
Nowadays, with the rapid development of electronic information technology, electromagnetic radiation and pollution originating from electronic devices pose a threat to human health and information safety [1,2,3,4,5,6] and the design and fabrication of microwave absorption materials which can dissipate microwave energy efficiently has become an urgent requirement [7,8,9]
The as-prepared TiO2/reduced graphene oxide (rGO) composites consist of TiO2 nanorods with diameters of 20–50 nm and lengths up to 100–300 nm, which are uniformly implanted on rGO nanosheets
TEM images in Figure 2 show the microstructures of amorphous TiO2 (a-TiO2)/rGO and crystalline TiO2 (c-TiO2)/rGO
Summary
With the rapid development of electronic information technology, electromagnetic radiation and pollution originating from electronic devices pose a threat to human health and information safety [1,2,3,4,5,6] and the design and fabrication of microwave absorption materials which can dissipate microwave energy efficiently has become an urgent requirement [7,8,9]. Many studies have combined graphene with other nanomaterials such as metals/alloys [31,32], ferrites [6,33,34], metal oxides/sulfide [35,36,37] and so on, which could achieve high magnetic or dielectric losses and add more loss mechanisms to improve their microwave absorption performance These results indicate that their microwave absorption properties were improved after introducing these materials. The addition of loss mechanism inevitably increases the complexity and difficulties of synthesis process, which limits the further practical applications of these materials Some shortcomings such as the poor physical or chemical stability, aggregation and high density of the introduced particles become new challenges for the design of microwave absorption materials. For the sample of a-T2, we prepared another two paraffin composites containing a-T2 of 10 wt% and 15 wt% to investigate the best mass ratio for microwave absorption
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