CO2-Derived Nanocarbons with Controlled Morphology and High Specific Capacitance

The conversion of CO2 to nanocarbons addressesa dualgoal of harmful CO2 elimination from the atmosphere alongwith the production of valuable nanocarbon materials. In the presentstudy, a simple one-step metallothermic CO2 reduction tonanocarbons was performed at 675 & DEG;C with the usage of a Mg reductant.The latter was employed alone and in its mixture with ferrocene, whichwas found to control the morphology of the produced nanocarbons. Scanningelectron microscopy (SEM) analysis reveals a gradual increase in theamount of nanoparticles with different shapes and a decrease in tubularnanostructures with the increase of ferrocene content in the mixture.A possible mechanism for such morphological alterations is discussed.Transmission electron microscopy (TEM) analysis elucidates that thenanotubes and nanoparticles gain mainly amorphous structures, whilesheet- and cloud-like morphologies also present in the materials possesssignificantly improved crystallinity. As a result, the overall crystallinitywas preserved constant for all of the samples, which was confirmedby X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS)techniques. Finally, electrochemical tests demonstrated that the preparednanocarbons retained high specific capacitance values in the rangeof 200-310 F/g (at 0.1 V/s), which can be explained by themeasured high specific surface area (650-810 m(2)/g),total pore volume (1.20-1.55 cm(3)/g), and the degreeof crystallinity. The obtained results demonstrate the suitabilityof ferrocene for managing the nanocarbons' morphology and openperspectives for the preparation of efficient "green"nanocarbon materials for energy storage applications and beyond.