Molecular electrochemistry at well-defined surfaces : studies of organics at pt (lll)‎ by auger, eels, leed, and electrochemistry

Abstract EN

Surface electrochemical studies are described here in which molecular layers were allowed to form from aqueous solutions at well-characterized by surfaces.

The resulting adsorbed molecular intermediates were characterized by use of surface spectroscopic methods, and examined as to electrochemica reactivity by means of cyclic voltammetry.

Compounds studies include (3-pyrid\i) hydroquinone (3PHO), pyridine (PYR), and a series of straight-cham terminal alkenoic acids having various chain lengths.

Molecular packing densitie (moles adsorbed per unit area) from solution at controlled pH and electrode potential were measured by means of Auger spectroscopy.

Vibrational spectra of the adsorbed layer formed from each compound were obtained by mean> of high-resolution electron energy-loss spectroscopy (EELS).

Surface structuer was probed by means of low-energy electron diffraction (LEED).

3PHQ and PYR are found to chemisorb at Pt(lll) in a tilted vertical orientation with an angle of 70-75° between the ring and the Pt surface.

Platinum-nitrogen bonding is evidently the predominant mode of surface attachment.

On the other hand, the alkenoic acids chemisorbed at Pt(lll) predominantly through the C=C double bond with the C=C axis parallel to the surface.

Adsorbed layers formed from all of these compounds were found to be stable in vacuum.

Electrochemical reactivity of these adsorbates correlates closely with adsorbate molecular structure and the mode of chemical bonding to the surface.