Sonochemical Synthesis of Carbon-related Nanomaterials in Liquid at Room Temperature

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The present study is concerned with the application of a power ultrasound to chemical syntheses of carbon and carbon- related nanomaterials in liquid phase at around room temperature.(1)Ultrasonication to o-dichlorobenzene (o-DCB) and some other benzene derivatives caused the darkening of the liquid, which is due to polymerization of benzene rings. Long irradiation such as 1 h resulted in the formation of black precipitates, which was found to be a round-shaped nanoparticle of graphite by transmission electron microscopy.(2)Ultrasonication to the benzene derivatives also induced the breakage of benzene rings and the formation of methyl and methylene group, which were confirmed by an infrared spectroscopy.(3)Addition of solid particles such as metals and inorganic salts greatly enhanced the polymerization or the formation of nanoparticles. When metallic particles of Co and Ni were co-added, granular and needle-like particles were obtained. TEM analysis revealed that the needle-like particles were solid, amorphous, and likely to deform when an electron beam was focused for a long time. It was inferred that this particles was a low weight polymer which were formed just like a yarning from a sticky liquid.(4)Addition of zinc nitrate induced the solid needles, while co-addition of zinc nitrate and metallic zinc induced the hollow needles from the ultrasonication of o-DCB. In the case of sole addition of metallic zinc, unexpectedly, hexagonal nameplates of zinc oxide were produced. A variety of referential experiments proved that oxygen in air dissolved in o-DCB and then reacted with metallic zinc. It was also found that a moderate sonication was more efficient for the crystal growth than an excessive sonication.