Cobalt disulfide nanosphere dispersed on multi-walled carbon nanotubes: an efficient and stable electrocatalyst for hydrogen evolution reaction

Novel cobalt disulfide on multi-walled carbon nanotubes (CoS2/MWCNTs) was synthesized via a facile one-step hydrothermal method in the presence of cetyltrimethyl ammonium bromide. The physical properties of as-prepared materials were characterized by Fourier transform infrared spectrum, X-ray diffraction, Raman spectrum, and scanning electron microscopy techniques. Physical characterizations revealed that cattierite CoS2 nanospheres dispersed on the surface of MWCNTs uniformly. In addition, electrochemical performances of as-prepared materials for hydrogen evolution reaction were investigated by polarization curves, Tafel plots, and electrochemical impedance spectrum in 0.50M H2SO4 electrolyte. It was demonstrated that MWCNT-based electrode exhibited almost no current response while CoS2/MWCNT nanocomposite-based electrode exhibited better electrochemical performances than pure CoS2-based electrode, including lower potential of -257mV for 10mAcm(-2) and smaller Tafel slope of 83mVdec(-1). Furthermore, CoS2/MWCNT nanocomposite retained its high activity even after 1000cycles of cyclic voltammetry scans, demonstrating superior stability under acidic condition. The enhanced electrocatalytic activity of CoS2/MWCNT nanocomposite-based electrode was ascribed to more exposed sulfur edges of CoS2, larger accessible surface area, and higher conductivity derived from MWCNTs. The results suggested that CoS2/MWCNT nanocomposite had a potential application to hydrogen evolution reaction.