Rutile TiO<sub>2</sub> Nanoparticles Encapsulated in a Zeolitic Imidazolate Framework-Derived Hierarchical Carbon Framework with Engineered Dielectricity as an Excellent Microwave Absorber
Jingjun Ding, Lei Wang, Yunhao Zhao, Xue‐Feng Yu, Linshen Xing, Guangzhou Ding, Jie Zhang, Renchao Che
Abstract
Aiming to solve the poor response of titanium dioxide (TiO 2 ) in the microwave frequency, versatile series of N-doped carbon (NC) components are employed to improve the conductivity and polarization strength of TiO 2 -based composites. The bimetallic zeolitic imidazolate framework-derived TiO 2 @NC complex (TNC-3) exhibits hierarchical microstructures and large-scale hetero-interfaces, whereas the pyrolysis composite of metal–polydopamine-coated TiO 2 (TNC-4) possesses the vesicle-like NC shell and bulk TiO 2 core. Thus, the optimal reflection loss and efficient absorption bandwidth of TNC-3 realize −44.0 dB at 3.0 mm and 5.4 GHz at only 2.0 mm of coating thickness, respectively. Nevertheless, the corresponding attenuation ability of TNC-4 is separately −24.3 dB and 4.8 GHz with a thickness of 5.0 and 2.0 mm, respectively. Importantly, the conduction and polarization loss can be enhanced by the large-scale interfacial contacts between nanoscale rutile nanoparticles and hierarchical graphitized carbon. Meanwhile, the superior performance of TNC-3 stems from the large proportion of pyridinic N and pyrrolic N, which provides asymmetric lone pairs to strengthen the dipole rotation. These results are of great value in constructing semiconductor-based complexes by carbon-coating engineering as functional materials.