Carbon monoxide oxidation on Au(1 1 1) surface decorated by spontaneously deposited Pt

Platinum is deposited spontaneously on Au(1 1 1) surface from 1 mM H2PtCl6 + 1 M HClO4 solution using multiple deposition procedure. X-ray photoelectron spectroscopy (XPS) analysis has shown that after immersion into the Pt containing solution and rinsing with water, Pt(OH)2 resides on the Au(1 1 1) substrate. Consecutive depositions as well as in situ scanning tunneling microscopy (STM) and electrochemical measurements are performed on previously electrochemically reduced Pt/Au(1 1 1) surfaces. Only homogeneous distribution of thus deposited Pt islands is observed by in situ STM. With subsequent depositions, the width of deposited Pt islands increases, but stays lower than 10 nm, while a significant increase of Pt islands height is observed, leading to moderate increase of the coverage. Cyclic voltammetry (CV) profiles of obtained Pt/Au(1 1 1) surfaces, and CO stripping curves are recorded in 0.5 M H2SO4 solution. CO oxidation takes place only at higher potentials shifting negatively with increasing coverage. This is discussed with respect to Pt islands width and height distributions and to the influence of the Au(1 1 1) substrate surface.