Self-Organization Based Fabrication of Bimetallic PtPd Nanoparticles on Transparent Conductive Oxide Substrates

Bimetallic PtPd nanoparticles are of special interest for their tunable properties in a wide range of applications as plasmonics, energy storage, catalysis. So, in this work we present a simple and versatile method for the production of bimetallic PtPd nanoparticles on a transparent and conductive substrate, such as fluorine-doped tin oxide/glass (FTO/glass) substrate. The method is based on the deposition of thin Pt/Pd bilayers on the FTO substrate. Then, we induced the melting, alloying, and dewetting process of the Pt and Pd layers by nanosecond laser irradiation with the consequent formation of the bimetallic PtPd nanoparticles. We characterized the nanoparticles by Scanning Electron Microscopy, Rutherford backscattering spectrometry, and X-Ray Diffraction measurements. In particular, the microscopic analysis showed that the average diameter of the nanoparticles is independent on the thickness of the deposited bilayers and on the layers sequence. On the other hand, the X-ray diffraction measurements confirmed that the structure of the nanoparticles consists in a PtPd alloy structure. The formation process of the nanoparticles is, finally, discussed on the basis of the general microscopic mechanisms involved in the laser-induced melting, alloying, and dewetting of the metallic films.