Fabrication of chlorine nitrogen co-doped carbon nanomaterials by an injection catalytic vapor deposition method

Abstract

The synthesis of both covalently bonded chlorine and nitrogen-doped carbon materials (Cl-N-CNMs) has been little studied. In this paper we report on the investigation of the synthesis of Cl-N-CNMs using a feedstock containing a mixture of dichlorobenzene (DCB), acetylene and acetonitrile over a Fe-Co/CaCO₃ catalyst using an injection CVD method at 800 °C. By varying the acetonitrile:DCB concentration ratio (66.7:33.3; 33.3:66.7 and 20:80), the morphology and physicochemical properties of the CNMs was varied. The products contained varying amounts of Cl (0.5%–1.2%) and N (0.88%–1.47%) and the total amount of Cl and N increased with the Cl content in the feed, as determined by XPS. A graphitic N environment dominated in feeds containing 33.3 and 66.7 vol.% DCB, whilst pyrrolic N dominated in feeds containing pure acetonitrile and 80 vol.% DCB. The chlorine in the feed promoted the formation of CNMs with various shapes namely horn-shaped, spaghetti-like, and pencil-like shapes, some with open-ends and others with closed-ends as determined by TEM and SEM studies. Although no direct correlation with the amounts of the reactants used and the morphology of the products was established, trends in the product shapes were noted with highly defected products produced from 66.7 vol.% DCB, and feeds containing 33.3 and 80 vol.% had tubes with similar open-ended horn-shaped morphology and less defects.