The chemical synthesis in solution and characterization of transition metal dichalcogenide MX2 (M = Mo, W; X = S, Se) nanoparticles

MX2 nanoparticles, with M = ?Mo, W and X = ?S or Se, were synthesized via a chemical reaction between molybdenum carbonyl (or tungsten carbonyl) and chalcogen dissolved in para-xylene solution. X-ray diffraction and high-resolution transmission electron microscopy analysis showed that the MoS2, WS2, MoSe2 and WSe2 powders were constituted of rounded amorphous nanoparticles. Upon annealing at 550??C the nanoparticles crystallized, losing their round shape. The four materials synthesized under similar conditions showed that the annealed selenide nanoparticles (MoSe2 and WSe2) are well crystallized, with aligned stacks of 5?10?layers (002 van der Waals (vdW) planes), while the annealed sulfide nanoparticles (MoS2 and WS2) exhibit curved and tangled 002 planes, randomly distributed in the particle.