Janus materials are attracting intense interest due to their exceptional possibilities in the design of structures with specific properties. In this work, Janus structures were constructed by the functionalization of free-standing single-walled carbon nanotube (FS-SWCNT) membranes with silver nanoparticles (AgNPs) electrodeposited on one face of the free-standing structure. The modification of the FS-SWCNT films with AgNPs was carried out from an ionic liquid solution, a green and environmentally friendly procedure. Before the functionalization of the free-standing membranes, the optimal electrodeposition conditions of AgNPs from an ionic liquid in different carbon substrates were studied. We demonstrate by UV-vis spectroelectrochemistry that the functionalization of the FS-SWCNT membranes on only one face is achieved, remaining unmodified the other face, as SEM images confirm. Moreover, the morphology of AgNPs, and, consequently, the properties of the Janus structures strongly depend on the specific electrodeposition conditions selected, determining their future applicability. (C) 2017 Elsevier Ltd. All rights reserved.