Magnetic graphene@PANI@porous TiO₂ ternary composites for high-performance electromagnetic wave absorption

Abstract

A two-step strategy combining in situ polymerization and a hydrothermal process has been developed for coupling polyaniline (PANI) with porous TiO 2 anchored on magnetic graphene. The microstructure and morphology of magnetic graphene@PANI@porous TiO 2 were characterized by FETEM, FESEM, XRD, XPS and VSM in detail. The results indicated that magnetic graphene@PANI was completely covered by porous TiO 2 with random orientations and the saturation magnetization value of the composite was 19.2 emu g À1 . PANI was used to decrease the absorber thickness, while the porous TiO 2 with a large surface area was designed to enhance the interaction between the electromagnetic (EM) wave and the absorber through multiple reflections, thus enhancing EM wave absorption properties. As an EM wave absorber, the maximum reflection loss of the composite was up to À45.4 dB due to the better normalized characteristic impedance (close to 1) at a thickness of only 1.5 mm and the absorption bandwidths exceeding À10 dB were 11.5 GHz when the thickness ranged from 1 to 3.5 mm. The excellent EM wave absorption performance was ascribed to the combined contribution from the enhanced dielectric relaxation processes, the unique porous nanostructures, the quarter-wave length matching model and the well-matched normalized characteristic impedance. Consequently, it is believed that the composite could be used as an excellent EM wave absorption material and the two-step strategy offered an effective way to design a high-performance EM wave absorber with a relatively thin thickness.

Boosted Interfacial Polarization from Multishell TiO2@Fe3O4@PPy Heterojunction for Enhanced Microwave Absorption

“…In addition, the moderate attenuation constant and impendence matching also make the TF@PPy composite a prospect candidate for the excellent MA material (Figure S4, Supporting Information). Compared with other relative absorbers ( Table ), the hierarchical TF@PPy composite demonstrates considerable merits such as enhanced absorption properties, adjustable absorption frequency, and thin coating thickness (Figure g–i), which cater to the requirements of wider applicability in the microwave absorption . As mentioned above, the involved microwave absorption mechanisms can be divided into the following aspects ( Scheme ): a)Polarization loss: By comparing with TiO 2 @Fe 3 O 4 , the complex permittivity of TF@PPy increases significantly, demonstrating the excellent dielectric properties (Figure a,b).…”

Investigation of the Broadband Microwave Absorption of Citric Acid Coated Fe3O4/PVDF Composite Using Finite Element Method

“…Furthermore, the resonance was observed to rise with an increase in the amount of C-Fe 3 O 4 loaded in the PVDF matrix. This finding suggested that multiple polarization mechanisms occur in the samples with alteration of the EM field frequency [27]. Firstly, electron mobility between Fe 2+ and Fe 3+ ions as the wave travel within the material can generate dipole polarization.…”

One‐step in situ growth of magnesium ferrite nanorods on graphene and their microwave‐absorbing properties

“…However, the single ferrites cannot meet the increasingly high requirements for absorbing materials. The hybrid materials are widely regarded as ideal candidates for the absorbing application …”

“…The hybrid materials are widely regarded as ideal candidates for the absorbing application. [22][23][24] Graphene is a new member of the carbon family, but has attracted worldwide attention since its discovery in 2004. Graphene possesses great electronic, mechanical and thermal properties.…”