| The exceptional catalytic activity of Pt for a number of important industrial reactions prompted this investigation into the formation of nanoparticulate Pt using a metal salt/sodium ethoxide synthesis based on a sol-gel derived methodology. It was found that using this synthetic route, nanoparticles of metallic Pt (up to 3 nm in dia.) were formed and remained suspended in the solution phase, allowing them to be deposited on substrates in a facile manner. A combination of CV and ICPAES was used to show that approximately 75% of the optimum Pt precursor (H2PtCl6) was converted to metallic Pt. The remaining 25% was reduced to a Pt(II) species, which, in this work has been identified as a sodium analogue (NaPtCl3(C 2H4)) of Zeise's salt (KPtCl3(C2H 4)). This identification was based on results from XPS, NMR and XANES. The optimisation of the sol and films formed from it was also carried out, including investigations of the effect of the reducing agent, Pt precursor, reactant ratio, sol ageing, synthesis temperature and time, as well as film formation rate, drying temperature and time, and substrate. It was found that the optimum sol was composed of a 2:1 NaOC2H5 to H 2PtCl6 mixture, refluxed for 2 hrs under Ar. An ideal film was formed when dried at 200°C for 15 min.; A similar synthetic route was then used to form Ru and Pt/Ru sols. The Ru sols were found by TEM to contain nanoparticles smaller than ca. 7 nm, although CV was unable to identify whether they were composed of Ru metal or Ru oxide.{09}Similarly, Pt/Ru sols contained nanoparticles ca. 2 nm in dia., composed, possibly, of a Pt/Ru alloy which was found to be extremely resistant to sintering. |
