New reactor for production of tungsten disulfide hollow onion-like (inorganic fullerene-like) nanoparticles

MS₂ (M=Mo, W) hollow onion-like nanoparticles were the first inorganic fullerene-like (IF) materials, found in 1992. Understanding of the IF-MS₂ growth mechanism in 1996 enabled us to build a rather simple reactor, which produced about 0.4 g per batch, of an almost pure IF-WS₂ powder. Soon after, it was found that the new powder showed better tribological properties compared with the regular MS₂ (M=Mo, W) powder, which is a well-known solid lubricant. The present work shows a new synthetic approach, which allows for a scale-up of IF-WS₂ production by more than two orders of magnitude. The falling-bed and, especially, fluidized-bed methods, which are presented here, pave the way for an almost ideal growth condition of the IF synthesis from an oxide precursor. As a result, the presently produced IF has a more uniform (spherical) shape and can grow to a larger size (up to 0.5 μm). It is expected that the relatively spherical IF-WS₂ nanoparticles, which are produced by the falling (fluidized) bed reactor, will exhibit superior tribological properties, than reported before.