Fabrication of TiO2/Pt core–shell particles by electroless metal plating

An electroless metal plating method was used to form Pt shells on sub-micrometer-sized titania particles fabricated by a sol–gel method. The electroless metal plating method comprised three steps: (1) surface-modification of titania particles with poly(diallyldimethylammonium chloride) (PDADMAC) (TiO2–PDADMAC), (2) pre-deposition of Pt nuclei or Pt fine particles on the titania particles by reducing Pt ions in the presence of TiO2–PDADMAC particles (TiO2–Pt) and (3) growth of the pre-deposited Pt by immersing the TiO2–Pt particles in a Pt-plating solution. TEM observation and X-ray diffractometry revealed that surface modification with PDADMAC promoted the pre-deposition of Pt and that crystalline Pt shells with a thickness of approximately 25 nm were successfully produced on the titania particles using initial concentrations of 0.8 × 10−3 M TiO2 and 0.375 × 10−3 M Pt in the Pt-plating solution.