Substitutional–interstitial structural transition in Cu–Pt nano-alloys

Copper–platinum alloys are important binary alloys in catalysis. In this communication, we demonstrate that it is possible to preserve the thermal properties of platinum with a copper–platinum alloy by converting the substitutional alloy into an interstitial one. This conversion occurs when the size of the copper–platinum system is reduced down to the nanoscale. The size-dependent phase diagram of Cu–Pt for a spherical nanoparticle is calculated at various sizes (50, 10 and 5 nm) demonstrating that Cu–Pt alloyed nanoparticles can be formed all over the composition range. Experimentally, the electron microscopy characterization of copper–platinum alloyed nanoparticles synthesized by wet chemistry supports the predicted structural transition.