Two Suitable Methods for the Preparation of Inorganic Fullerene-Like (IF) WS2 Nanoparticles

  Two facile and low cost routes were used for the synthesis of IF-WS2 nanoparticles. In this paper, preparation of IF-WS2 nanoparticles with two different methods was investigated. In the first method, WO3 nanoparticles were reacted with H2S gas in N2/H2 reducing atmosphere at 900 oC. The as-synthesized IF-WS2 nanoparticles are spherical shape with an average size of about 70 nm.  In the second method, WO3 nanoparticles were reacted with Sulfur powder in H2 reducing atmosphere at 800 oC. All reaction conditions have been optimized. In this method, application of the harmful and poisonous H2S gas was eliminated. The as-prepared IF-WS2 nanoparticles are spherical shape with an average size of about 50 nm. In this research, it was revealed that in the first method, the reduction of WO3 nanoparticles before the reaction with H2S gas is very important in product quality and the output of the reaction will be increased. Also in contrast to that was proposed in the previous similar research, it was revealed that the preparation of IF-WS2 nanoparticles according to the second method can not be considered as large scale method because the product quality is directly dependent on the amount of WO3 nanoparticles that can not be considered exceeding 0.1 g. Besides, the preparation method of WO3 nanoparticles as precursor for the synthesis of IF-WS2 nanoparticles is different from previous similar researches. The solution of ammonium para tungstate (APT) and citric acid (as organic additive) was prepared and then the pH of solution was adjusted at 7 by using ammonium hydroxide. Firstly, the sample was heated to 250 oC for 1 h and secondly was calcined at 500 oC for 2 h to obtain yellow color powder of WO3 nanoparticles with an average size of about 50 nm. The samples were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).