Two facile routes for functionalization of WS$_2$ nanotubes with silver nanoparticles

Silver-coated WS$_2$ nanotubes (NT-WS$_2$) were successfully synthesized via two wet chemistry techniques. The first employs spontaneous silver nanoparticle growth resulting from an interaction of disulfide nanotubes with AgNO$_3$ in aqueous suspensions at 100$^\circ$ C without any additional reducing agents or stabilizers. The second utilizes [Ag(NH$_3$)$_2$]OH complex to produce silver nanoparticles upon thermal decomposition. Both techniques are capable of producing Ag-NT-WS$_2$ nanocomposites containing 5–60 nm silver nanoparticles tightly attached to the nanotubes' surfaces. The hexagonal arrangement of sulfur atoms of the outer WS$_2$ layer was postulated to facilitate crystallization of silver nanocrystals with hexagonal crystallographic system (4H-Ag). The physical-chemical model for spontaneous AgNP formation is proposed.