Toward facile synthesizing of diamond nanostructures via nanotechnological approach: Lonsdaleite carbon nanofibers by electrospinning

Low cost synthesis of the diamond is a dream for the scientists. In this study, different forms of carbon were obtained due to utilizing of different cobalt-based catalytic materials in the graphitization of poly(vinyl alcohol) (PVA) electrospun nanofibers. The utilized cobalt-based catalysts were cobalt acetate tetrahydrate (CoAc), cobalt NPs, and CoAc/palladium NPs. Calcination in argon atmosphere of the polymeric nanofibers containing the aforementioned catalytic materials led to obtain different products. High yield and good nanofibrous morphology were obtained in case of CoAc-containing nanofibers, however cobalt nanoparticles destroyed the nanofibrous morphology and revealed low yield. Interestingly, diamond-like lonsdaleite carbon nanofibers were produced when CoAc–Pd NPs catalytic system was utilized; however normal graphite powder and nanofibers were obtained when Co NPs and CoAc have been used, respectively. The obtained Co-graphite and Co–Pd–lonsdaleite nanofibers could be also synthesized in the form of thin films supported on graphite disks when polyacrylonitrile disks were used as collectors. Calcination of the obtained disks with the attached electrospun nanofibers produced well affixed Co-graphite and Co–Pd–lonsdaleite nanofibers on graphite disks. Electrical properties study of the obtained films indicated that the Co–Pd–lonsdaleite nanofibers behave as semiconductor while Co-graphite nanofibers show ohmic conductivity. Magnetically, Pd has a negative impact on the magnetic properties of the cobalt.

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► Diamond-like Lonsdaleite carbon nanofibers were produced using the electrospinning.
► The produced nanofibers reveal semiconducting behavior.
► Beside producing lonsdaleite, Co–Pd catalytic system enhanced the graphitization yield.