Tingyuan Huang

Solvothermal synthesis of flower-like CoS hollow microspheres with excellent microwave absorption properties

In this study, flower-like CoS hollow spheres (CHSs), synthesized via a facile solvothermal method in the presence of CTAB, were initially investigated as microwave absorbers. It was found that such microstructure was significantly different from CoS nanoparticles (CoS NPs) prepared without introducing CTAB under similar preparation conditions. Moreover, with a low filler loading of 20 wt%, CHSs based composite could reach an optimal reflection loss of −43.6 dB at 15.6 GHz, and exhibit an effective absorption bandwidth (below −10 dB) of 4.6 GHz (13.2–17.8 GHz) at the thin thickness of 2.0 mm. Furthermore, through adjusting the thickness from 2.0 to 5.0 mm, an effective absorption bandwidth of 13.2 GHz could be monitored in the frequency range of 4.8–18.0 GHz. The results indicate that the novel CHSs are intriguing microwave absorbers with the advantages of strong absorption, broad bandwidth, light weight and thin thickness, which is attributed to the unique nanoarchitecture, extra void space, and high dielectric loss.

Synthesis of a hollow CeO2/Au/C hierarchical nanostructure for high catalytic activity and recyclability

We report uniform hollow CeO2/Au/C nanocatalysts with hierarchical structures fabricated successfully via an etching process. The whole preparation method involves the synthesis of SiO2 spheres, a sequential deposition of CeO2, Au NPs of 2–5 nm and then C layers through hydrothermal processes, crystallization of C by calcination and finally etching of the inner silica spheres to construct the hollow structures. The as-obtained nanostructures are characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), UV-Vis spectroscopy and energy dispersion X-ray spectroscopy (EDX). The CeO2/Au/C composite shows a multilayer structure including the hollow ceria spheres and the C layers, where Au NPs are located between the two layers. In this work, the reduction of 4-NP is employed as a model reaction to test the catalytic performance. The results indicate that the hollow CeO2/Au/C nanospheres exhibit a higher catalytic performance, comparing with the hollow CeO2/Au and Au/C nanospheres. The presences of the C shells and CeO2 layers can improve the catalytic activity. In addition, the hollow CeO2/Au/C structures can be easily recycled without an obvious decrease of the catalytic activities in the reaction.