Synthesis and Mechanism of Micron―level Hollow CarbonRosary Structures

Usingreduced iron powder and activated carbon as starting materials, micron―levelhollow carbon rosary structures were synthesized by thermal CVD method. Their morphology,composition and specific surface area and pore―size distribution of the productwere characterized by TEM, HRTEM, EDS and N2 adsorption apparatus.With dozens microns in length and 1―2 μm in diameter, the rosarystructures were formed by hollow carbons. The hollow carbon actually wasgraphite shells with 3―5 nm in thickness. Thespecific surface area SBETof the product was up to 306.523 m2/g, and the pore―size was mainlydistributed in the mesoporous range, whose peak mark at 3.761 nm. The mechanismof the product can be described as follows, carbon was precipitated in the formof graphene pieces at lower temperature by iron/C droplet, which epitaxiallygrew on iron/C droplet and formed graphite shells. The graphite shells andiron/C droplet constituted shell/core structures. The contraction trend ofgraphite shells squeezed the iron/C droplet along the axial direction. Theprocesses above repeated and the carbon rosary structures formed. The product may have potential applications in the energy―savingmaterials, supporter materials for drugs/dyes/catalysts, hydrogen/energystorage materials.