Enhancement of defects on nitrogen-doped carbon nanomaterials via chlorination: Experimental and theoretical studies

The role of chlorine in enhancing defects in nitrogen-doped carbon nanomaterials (CNMs) was investigated via pyrolysis chemical vapour deposition (CVD) method. Tetrachloroethane (TTCE) and acetonitrile (CH3CN) were used as sources of chlorine and nitrogen, respectively. Nanomaterials with variable morphologies were obtained when the amount of TTCE was varied in the feed. Carbon nano-onions were found to be the dominating nanomaterials for CNMs generated from room temperature feed mixtures, which confirms functionalization and doping of CNMs with chlorine and nitrogen. The degree of defects was enhanced in CNMs generated from heated feed mixtures, which was evidenced by the formation of mixtures if irregular branched bamboo-compartmented nanotubes and nano-necklaces, coiled carbon nanotubes (CNTs), and broken bamboo-compartmented CNTs. The amount of defects in CNMs was enhanced in CNMs generated from heated mixtures, evidenced by increased ID/IG intensity peak ratio obtained from Raman spectroscopy analysis. Types of defects were also identified from XPS and Raman spectroscopy analysis ranging from boundary-like, vacancy-like, hoping and on-site defects. Theoretical calculations via DFT of CNMs generated from all room temperature feed mixtures revealed the emanation of a C–Cl peak at the conduction band TDOS which emanated due to the generation of an unoccupied mid-gap state which originates from the sp3 hybridized defect brought by neutral chlorine adducts.

Keywords: Defects, Chlorine, Carbon Nanomaterials, Theoretical Calculations.