Laser ablation synthesis of mono- and bimetallic Pt and Pd nanoparticles and fabrication of Pt-Pd/Graphene nanocomposites

Mono-metallic and bi-metallic Palladium and Platinum nanoparticles find important applications for sensing detection, catalysis, hydrogen storage, fuel cell etc. However, the success of such technologies is subjected to the development of simple, versatile, low-cost, high-throughput methods for the production of the nanoparticles with desired sizes or composition. In particular, we present a laser-assisted synthesis method for the production of stable mono- and bi-metallic Pd and Pt nanoparticles. It is based on the nanosecond-pulsed laser ablation, in liquid environment, of pure Pd or Pt targets and of PtPd composite target at different ablation times. We characterized nanoparticles' morphology and crystalline structure by Transmission Electron Microscopy, Selected Area Electron Diffraction, X-Ray Diffraction and Energy Dispersive X-Ray measurements. In particular, the microscopic analysis showed that the average diameter of the nanoparticles is around 10-15 nm. The stability of the solutions was checked by UV-vis spectroscopy. Furthermore, by Scanning Transmission Electron Microscopy we found that, in bimetallic nanoparticles, Pt and Pd are homogeneously distributed on the whole volume of particle. In addition, we used the produced nanoparticles to decorate graphene layers by simple spin coating of the colloidal solutions onto the substrates, obtaining nanoparticles/Graphene nanocomposites with a "starry sky" type morphology. Also, trough Scanning Electron Microscopy images, the surface density of the nanoparticles on graphene was evaluated. We establish, therefore, a general working framework for the controlled nanofabrication of nanoparticles/graphene nanocomposites that could find interesting applications in catalysis and in electronic devices.