Adsorption properties of crystalline and amorphous PdIr nanoparticles. A systematic first-principles study

Abstract

The great interest in metal nanoparticles is due to the fact that the transition from micro to nano size leads to huge changes in the physical and chemical properties of the material. The local atomic structure and composition can significantly influence the properties of nanoparticles. First-principles calculations are used to study the influence of the structure and chemnical ordering of IrPd nanoparticles on the electronic properties, charge distribution and adsorption energy of O, H, CO, NO, OH. Three different types of PdIr bimetallic nanoparticles with different chemical ordering are considered, namely Pd-core/Ir-shell (Pd@Ir), Ir-core/Pd-shell (Ir@Pd), and bimetallic alloy (Pd-Ir) particles consisting of 79 and 321 atoms with fcc and amorphous structures. The electronic and adsorption properties of the proposed nanoparticles are extensively studied in terms of their ability to adsorb O, H, CO, NO, OH, which opens up the possibility of fine-tuning their properties by modifying the atomic structure and composition. By adjusting the core–shell ratio, the adsorption energy on the nanoparticle surface can be fine-tuned, especially in fcc nanoparticles. This results in a narrower range of adsorption energies, which cannot be achieved with bimetallic alloys. In the case of amorphous nanoparticles, the adsorption energy is highly variable because to there are many non-equivalent adsorption sites on the surface.