Confinement effects on the shape and composition of bimetallic nano-objects in carbon nanotubesElectronic supplementary information (ESI) available: Materials and methods, TEM of CoPt, and FePt NPs, TEM of empty CNTs, TEM of filled CNTs, XRD of NWs@CNTs, TEM of partially coalesced FePt NPs in CNT2f. See DOI: 10.1039/c5cc09037g

CoPt and FePt nanostructures have been efficiently confined in carbon nanotubes (CNTs). A marked confinement effect has been evidenced, both on bimetallic nano-object shape and composition. In large diameter CNTs small Co- and Fe-rich nanoparticles are formed, while in small diameter CNTs Pt-rich nanowires are selectively produced. The shape and the composition of bimetallic alloys prepared by in situ reduction of molecular precursors depends on the carbon nanotube diameter.