Effect of Ir sandwich layers on thermal stabilities of Pd-Ir-Pt core-sandwich-shell nanoparticles: a molecular dynamics simulation

Abstract

During the last few decades, Pt core-shell nanoparticles comprising of noble and non-noble metals, with their low cost and much improved catalytic performances, have attracted a lot of interest in research. However, electrochemical instability of Pt can cause a lack of catalytic activity, and continuous loss of surface area that is active.[1] Worldwide organizations such as U.S. Department of Energy (DoE),[2,3] Japanese New Energy and Industrial Technology Development Organization (NEDO),[4] have set high standards which create the need to increase the electrocatalysts’ activity and durability.[5] Coupled with the increased need for clean and efficient power, there is real need to look for more ways to constantly improve the catalyst for better performance and durability. One of the ways to further improve the catalyst is the addition of a sandwich layer between the core and the shell to increase the stability which therefore increasing the nanoparticle catalyst’s durability. Iridium(Ir) is being chosen to be that sandwich layer due to its high melting point. Therefore, this project aims to find out how Ir sandwiched bimetallic nanoparticles will affect the thermal stability of the nanoparticle. The nanoparticle we will be using is Pd as a core and Pt as a shell. LAMMPS will be used to code the program and will be run with the help of the National Supercomputing Centre (NSCC). The result shows that as the number of layers of Ir increase, there is indeed an increase in the thermal stability. However, for 4 and 6nm nanoparticles, as the number of layers of Ir increase, the increments in the melting point started to decrease. Therefore, we can conclude that by adding the sandwich layer of Ir, the thermal stability of the core-shell nanoparticle Pd-Pt did increase. For future plan, other materials or alloys can be tested to be the sandwich material aiming to reduce the cost of the catalyst and to further improve the effectiveness and stability of the core-shell nanoparticle.