A shape-controlled method to functionalize multiwalled carbon nanotubes with Ni3S2

In this paper, we report the funtionalization of multiwalled carbon nanotubes (MWCNTs) with Ni3S2 using a solvent-thermal approach. The nanocomposites synthesized without ammonia show that the MWCNT's outer surface was uniformly coated with a Ni3S2 film appearing like centipede-shaped objects when characterized by scanning transmission electron microscopy and transmission electron microscopy images. Meanwhile, the Ni3S2 (l)ayer thickness can be changed by simply altering the concentration of reaction precursors and keeping the other reaction conditions constant. Interestingly, clustered Ni3S2 nanoparticles were formed along the outside surfaces of the MWCNTs when ammonia was added to the reaction solution while keeping all other conditions unchanged. Also, the sizes of Ni3S2 nanoparticles can be varied through varying the amount of ammonia in our reaction system. On the basis of our experimental results, we propose a dynamic-controlled Oswald ripening mechanism to elucidate the formation of the MWCNTs composites with centipede-shaped and clustered Ni3S2 morphologies.