Electrode potential dependent NMR spectra of surface 13CO on polycrystalline platinum

Abstract

The initial results of investigations of a solid/liquid interface under an external potential control using nuclear magnetic resonance are reported. The 13C nuclear magnetic resonance (NMR) spectra of CO formed on a polycrystalline platinum electrode via catalytic decomposition of methanol in aqueous media have been measured in a broad electrode potential range. The narrowing of the solid-like NMR peak at the most negative potentials to a single component at 0.225 V vs. the Ag/AgCl reference is interpreted as resulting from a transformation of a mixed (predominantly bridge- and linear-bonded) surface population to linear-bonded CO. Potential dependent T 1 measurements confirm the changes in bond configurations on the surface. Further oxidation produced solution carbon dioxide as evidenced by the solution-type NMR peak morphology. Our measurements represent the first successful attempt to study 13C adsorbates at the solid/liquid interface where the electrode potential was controlled via apotentiostat.