Correlation between the Knight shift of chemisorbed CO and the Fermi level local density of states at clean platinum catalyst surfaces
- Univ. of Illinois, Urbana, IL (United States). Dept. of Chemistry
Due to its fundamental importance in heterogeneous catalysis, as well as in electrocatalysis, the chemisorption and reaction of CO on transition metal surfaces has been an important focus of modern surface science. Here, the NMR spectroscopy of {sup 13}CO adsorbed onto transition metal surfaces has been shown to be a very powerful probe of molecular structure and dynamics of CO itself, as well as a probe of the electronic properties of the transition metal surfaces onto which it is adsorbed. The authors have investigated the {sup 195}Pt and {sup 13}C nuclear magnetic resonance (NMR) spectroscopy of clean-surface platinum catalysts and of CO chemisorbed onto Pt catalysts surfaces. They use Knight shift, relaxation, and J-coupling data to deduce information about the Fermi level local density of states (E{sub f}-LDOS) at catalyst surfaces. There is a linear correlation between the Knight shifts of chemisorbed CO and the clean surface E{sub f}-LDOS of platinum onto which the CO is bound, as determined by {sup 13}C and {sup 195}Pt NMR. The correlation amounts to {approximately} 12 ppm/Ry{sup {minus}1} {center_dot} atom{sup {minus}1}, the same as that which can be deduced for CO on palladium, as well as from the electrode potential dependence of {sup 13}C Knight shifts and infrared vibrational frequencies, {nu}{sub CO}, and the relationship between {nu}{sub CO} and the E{sub f}-LDOS at clean platinum surfaces. The ability to now directly relate meal and adsorbate electronic properties opens up new avenues for investigating metal-ligand interactions in heterogeneous catalysis and electrocatalysis.
- Sponsoring Organization:
- National Science Foundation, Washington, DC (United States); USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-91ER45439
- OSTI ID:
- 682616
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 13 Vol. 121; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
Similar Records
Probing the surface of a heterogeneous catalyst: double resonance of carbon monoxide chemisorbed on highly dispersed platinum
A detailed NMR-based model for CO on Pt catalysts in an electrochemical environment: Shifts, relaxation, back-bonding, and the Fermi-level local density of states