High-resolution electron microscopy study of mesoporous dichalcogenides and their hydrogen storage properties.

In this work, we report a detailed investigation on the surface topology of ordered mesoporous WS(2) nanoarrays nanocast from the silica SBA-15 template. Using a high-resolution scanning electron microscopy (HRSEM) technique, we acquire distinguishably clear images of the WS(2) surface. A large number of small nanorods are found to be evenly distributed among the nanowire arrays, supporting their ordered mesostructures. Based on these observations, tunnel-like connecting pores are proposed to have a similar distribution in the mother mesoporous silica SBA-15 template. Interestingly, we observe the atomic crystal lattices of the layered WS(2) on the HRSEM image. To the best of our knowledge, this is the first time that atomic crystal lattices have been directly observed using a SEM technique. In addition, both materials show good adsorption-desorption capabilities with hydrogen, and the maximum amount of hydrogen that can be taken up is 0.34 wt% for mesoporous WS(2) and 0.52 wt% for mesoporous MoS(2) at a pressure of 10 bar, indicating that both are potential hydrogen storage materials.