The chemical synthesis in solution and characterization of transition metal dichalcogenide MX_2 (M = Mo, W; X = S, Se) nanoparticles

摘要

MX_2 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 MoS_2, WS_2, MoSe_2 and Wse_2 powders were constituted of rounded amorphous nanoparticles. Upon annealing at 550 deg C the nanoparticles crystallized, losing their round shape. The four materials synthesized under similar conditions showed that the annealed selenide nanoparticles (MoSe_2 and Wse_2) are well crystallized, with aligned stacks of 5-10 layers (002 van der Waals (vdW) planes), while the annealed sulfide nanoparticles (MoS_2 and WS_2) exhibit curved and tangled 002 planes, randomly distributed in the particle.