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Metallic nanoparticles can be powerful catalysts for reactions such as the water gas shift reaction, which converts steam and CO to H$_2$ and CO$_2$ [1]. Depending on their composition, size, shape, and surface area, different nanoparticles exhibit different catalytic properties [2].
We investigated the shaping of spherical AuCu particles with 10 nm diameter using 2 keV Ar+ beams. This was done both through simulations using the binary collision approximation code SDTrimSP-3D, and experimentally, by comparing atomic force microscopy (AFM) images before and after irradiation with fluences of 0.5 ions/Å$^2$ and 1.0 ions/Å$^2$.
Simulation results show the top half of the particles eroded into a conical shape at fluences between 0.5 ions/Å$^2$ and 1.0 ions/Å$^2$. Beyond 2.0 ions/Å$^2$, the nanoparticles are eroded almost completely. Additionally, SDTrimSP-3D simulates changes in composition created by irradiation, predicting an enrichment of Au at the surface of the particles. AFM images are used to track the heights of the irradiated particles and those coincided well with the SDTrimSP-3D results.
[1] C. Ratnasamy and J. P. Wagner, „Water gas shift catalysis,“ Catalysis Reviews, vol. 51, p. 325–440, 2009.
[2] T. Ishida, T. Murayama, A. Taketoshi and M. Haruta, „Importance of Size and Contact Structure of Gold Nanoparticles for the Genesis of Unique Catalytic Processes,“ Chemical Reviews, vol. 120, pp. 405-408, 2020.