Bacteria are widely distributed in the natural environment and the surfaces of objects, bringing about much trouble in our lives. Varies nanomaterials have been demonstrated good effect on killing microbe, but the consistency and stability seem to be improved. Recently, antibacterial effect on surfaces of some natural nanostructures was recognized, and more and more evidences were provided as a new type of bactericidal mechanism, the physical sterilization. The dragonfly and cicada wings have been found to possess the most exceptional antibacterial properties because of the specific nanostructure. Inspired by the biofunctions, researchers began to build a series of physico-antimicrobial surfaces on different materials to avoid the abuse of antibiotics and the environmental pollution of organic antibacterial agents. The physico-antimicrobial structure does not rely on chemical components, and a series of physico-antimicrobial models have been established. To deeply understand the physically bactericidal effect, this article reviews a series of natural and biomimetic physical antibacterial surfaces and makes reasonable expectations for the application of such composite materials in constructing physical antibacterial surfaces.
Microwave-absorbing materials with good microwave absorption performance are of great interest for military applications and human health, which is threatened by electromagnetic radiation pollution. Herein, the design and synthesis of multi-componential metal-hybridized graphene composites via freeze drying and pyrolysis of ferrocene hydrazone complex precursor are reported. Various magnetic nanoparticles are loaded on reduced graphene oxide (rGO) via controlling their pyrolysis temperature. The complex electromagnetic parameters of these hybrids are therefore regulated by the hybrid components. Among them, rGO hybridized by the sea-island-like Fe2O3/Fe3O4/FeNi3 multi-componential metals shows a good balance of dielectric and magnetic constants. Thus, the improved impedance matching with free space brings about a superior electromagnetic wave absorption performance, especially on the effective absorption bandwidth. The minimum reflection loss (RL) of the hybrids is as low as −40.3 dB at 11 GHz with the RL bandwidth of −10 dB being 4.55 GHz (from 9.25 to 13.8 GHz).
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