Synthesis of carbon-encapsulated cobalt sulfide nanoparticles and their electrochemical property

Carbon coated cobalt sulfide (Co9S8) nanoparticles (C@Co9S8) with the size of 5 to 30 nm were synthesized in a controllable way. The products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and galvanostatic charge-discharge. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) examinations confirmed that the C@Co9S8 nanoparticles were uniformly dispersed in carbon matrix, and the Co9S8 nanoparticles were surrounded by several carbon layers with well-ordered arrangement. The nanoparticles exhibited well-constructed core-shell structures. The possible growth process for the C@Co9S8 was discussed briefly. The electrochemical measurements were examined in a three-electrode glass cell in 1.0 M H2SO4 solutions. The C@Co9S8 nanocomposites are demonstrated to be an excellent electrode material with good specific capacitance.