SFG and STM studies of the Pt(111) crystal face at atmospheric CO and oxygen pressures: preparation of platinum nanocluster arrays

Abstract

Studies of crystal surfaces at high pressures (ca. 1 atm) and during catalytic reactions become possible by the application of sum frequency generation (SFG) vibrational spectroscopy and scanning tunnelling microscopy (STM). We present the SFG spectra of CO on Pt(111) as a function of pressure and show evidence for the reversible formation of carbonyl clusters with a CO/Pt ratio of > 1 and for an incommensurate CO layer at high pressures. These species turn over rapidly to produce CO₂ during CO oxidation. STM studies show significant reconstruction of Pt(110) in both CO and O₂, while the surface structure of the Pt(111) crystal face exhibits only minor changes. Platinum nanocluster arrays in the 3–100 nm range have been produced by electron beam lithography. These cluster systems produced on different oxide supports can be used as model catalysts.