| Summary: | Interactions between incident electromagnetic energy and matter are of critical importance for numerous civil and military applications such as photocatalysis, solar cells, optics, radar detection, communications, information processing and transport et al. Traditional mechanisms for such interactions in the microwave frequency mainly rely on dipole rotations and magnetic domain resonance. In this study, we present the first report of the microwave absorption of Al/H2 treated TiO2 nanoparticles, where the Al/H2 treatment not only induces structural and optical property changes, but also largely improves the microwave absorption performance of TiO2 nanoparticles. Moreover, the frequency of the microwave absorption can be finely controlled with the treatment temperature, and the absorption efficiency can reach optimal values with a careful temperature tuning. A large reflection loss of −58.02 dB has been demonstrated with 3.1 mm TiO2 coating when the treating temperature is 700 °C. The high efficiency of microwave absorption is most likely linked to the disordering-induced property changes in the materials. Along with the increased microwave absorption properties are largely increased visible-light and IR absorptions, and enhanced electrical conductivity and reduced skin-depth, which is likely related to the interfacial defects within the TiO2 nanoparticles caused by the Al/H2 treatment. : Synopsis: Al/H2 treatment brings enhanced improvement in microwave absorption performance of TiO2 nanoparticles. Keywords: Microwave absorption, Black TiO2 nanoparticles, Hydrogenation, Aluminum reduction
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