Platinum nanostructures were synthesized by colloidal deposition,
analogous to the process reported by Sun et al.20 The electrode
chips were placed for 7 days in 2 ml of an aqueous solution
containing 2.9mMH2PtCl6 (ChemPur Feinchemikalien; Karlsruhe,
Germany) and 1.24 M HCOOH (Merck; Darmstadt, Germany). The
deposition was followed by the above described electrochemical
cleaning step.