Size and Shape Effects on the Phase Diagrams of Nickel-Based Bimetallic Nanoalloys

Nickel-based bimetallic nanoalloys (nickel-palladium, nickel-platinum, nickel-rhodium, and nickel-iridium) play an important role in catalysis, electrocatalysis, and magnetic applications. To improve the performance of those materials at the nanoscale, the knowledge of their phase diagrams is critically needed. However, such knowledge is still lacking because calorimetry experiments are extremely challenging to perform at the nanoscale. Then, a smart and necessary alternative to those challenging and time-consuming experiments is to obtain this knowledge from theoretical predictions by using nanothermodynamics. The phase diagrams at the nanoscale for the considered alloys are therefore predicted for various polyhedral shapes, while the nature of the surface segregated element is established by using two segregation rules. Finally, the theoretical results are supported by advanced transmission electron microscopy characterization.