Graphene-like structure of bio-carbon with CoFe Prussian blue derivative composites for enhanced microwave absorption.

Traditional carbon materials such as graphene are often applied in the field of electromagnetic wave (EMW) absorption but they have unbalanced impedance matching and high conductivity. Bio-carbon with graphene-like structure derived from apples has many advantages over graphene: it can be prepared in large quantities and the abundant heteroatoms present in the lattice can provide many polarization phenomena. Herein, Prussian blue analogue (PBA) as a source of magnetic component was combined with bio-carbon or reduced graphene oxide (rGO) to study the EMW absorption properties. The fabricated BC/CFC-12-7 displayed performance with a minimum reflection loss (RLmin) of -72.57 dB and a wide effective absorption bandwidth (EAB) of 5.25 GHz with an ultra-thin and nearly equal matching thickness at 1.61 mm. The results show that the good EMW absorption property of bio-carbon composites comes from good conduction loss, large relaxation polarization loss especially from pyridinic-N, and better impedance matching. The optimized radar cross section is found to be -33.55 dB m2 in the far-field condition using CST. This work explored the advantages of bio-carbon as a novel EMW absorbing material compared with graphene and provided ideas for realizing high-performance EMW absorbing materials in the future.

Photoluminescence and Growth Mechanism of Oriented Hierarchical Fibrous-Like ZnO Nanowires.

Oriented hierarchical fibrous-like ZnO nanowires with the diameter of about 30­50 nm and the length of about 15­30 um were successfully synthesized on the seed-coated Zn substrates by a simple two-step process. The morphology and structure of the obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It is shown that fibrous-like ZnO nanowires with the aspect ratio of about 500˜1000 present the dense reticular structure, which are grown on ZnO nanowire arrays. But beyond that, as-prepared samples are found to be good single crystalline with hexagonal wurtzite structure and preferential grow along the c-axis. A possible growth mechanism of oriented hierarchical fibrous-like ZnO nanowires is presented in detail, revealing that the synthesis of fibrous-like ZnO nanowires should be attributed to differences in the growth rate of the different crystallographic planes and the two growth ways. The photoluminescence (PL) spectra of oriented hierarchical fibrous-like ZnO nanowires grown at 240 min shows the 5 nm blue-shift and enhanced intensity property in the UV emission.