Synthesis of metal-incorporated graphitic microporous carbon terminated with highly-ordered graphene walls—Controlling the number of graphene layers by ambient-temperature metal sputtering

Metal-incorporated, graphitic microporous carbon, containing highly ordered graphene layers, has been converted from highly thin amorphous carbon film by a metal nanoparticle sputtering process at ambient substrate temperature. A standard direct-current magnetron sputtering system is used in this purpose. The process consists of a dual effect of activation and graphitization of amorphous carbon to graphitic microporous carbon. The sputtering plasma, containing energetic ions and sub-atomic particles, act as dry-etchant to activate the a:C film to transform it into microporous carbon. Whereas, the inelastic ‘knock-on’ collision between metal nanoparticles/ions and the nuclei of C atoms manifests the atom displacement and re-arrangement into ordered structure to form graphitic domains within the microporous carbon network. The average number of graphene layer formation has been controlled by adjusting the sputtering voltage and current, as the carbon atom displacement rate is dependent on the irradiation current density. Raman spectroscopy and scanning transmission electron microscopy confirms the high controllability of the number of graphene layer formation as a function of sputtering parameters. The method is simple, cost-effective and compatible with modern solid-state device fabrication processing, as it comprises vacuum-based physical vapor deposition techniques, and also, can be adopted easily for transitional metal incorporation into graphene and other carbon nanostructures for potential hydrogen storage and related clean energy applications.