Synthesis of Sulfur-Doped Carbon Nanotubes by Liquid Precursor

We describe the single-step synthesis of sulfur-doped carbon nanotubes (S-CNTs) from a dimethyl sulfide (C2H6S) precursor, using a simple chemical vapor deposition method. The S-CNTs were characterized by scanning electron microscopy, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL) spectroscopy, cyclic voltammetry (CV), and galvanostatic charge-discharge. TEM and EDS analysis show that the CNTs are coated with a dense sulfur medium. The optimal dimethyl sulfide vapor concentration for the formation of the S-CNTs is 5.55-7.03%. The optical property of the S-CNTs was also investigated at room temperature. The S-CNTs displayed a strong PL emission at 416.8 nm, which may be attributed to the dielectric screening of the sulfur doped on the CNT surface. The electrochemical measurements were examed in a three-electrode glass cell in 0.5 M Na2SO4 and 1.0 M H2SO4 solutions, respectively. The S-CNTs are demonstrated to be an excellent electrode material with good cyclic stability and specific capacitance.