Influence of foreign Fe ions on wet chemical synthesis of Pt nanoparticle thin films at ambient temperature: In situversus direct addition

Novel Pt nanoparticle thin films have been successfully synthesized on glass surfaces via a wet chemical method that comprised reduction of aqueous hexachloroplatinic acid solution by ascorbic acid in the presence of hematite (α-Fe₂O₃) at room temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), atomic absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-Vis absorption spectroscopy and a scratch testing method have been used to characterize the final and intermediate products of Pt films. It was found that there existed competition between precipitation of nanoparticles and formation of Pt nanoparticle thin films, which is controlled by the source of foreign Fe ions i.e. in situ or direct addition of foreign ions. Besides, the negatively charged glass surface and positively charged hematite surface under the synthesis condition of pH ∼3 assisted heterogeneous nucleation of Pt on glass surfaces. The measured adhesive strength of the film on glass substrate is 106 Mpa and the density of states overlaps the Fermi energy (E_f = 0), indicating the conducting films are strongly bonded on the glass surface. The synthetic protocol outlined here shows a new synthetic route to integrate metal nanoparticles directly on glass substrates.