Adsorption and electrooxidation of some simple organic molecules on rhodium(111) as probed by real-time FTIR spectroscopy: Comparisons with platinum(111)

Journal Article · Thu Oct 05 04:00:00 EDT 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100357a038· OSTI ID:6816317

Leung, Lam-Wing H; Weaver, M J ^[1]

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1. Purdue Univ., West Lafayette, IN (USA)

The electrooxidation pathways of seven simple organic molecules in 0.1 M HClO{sub 4} on ordered Rh(111) were examined by means of real-time sequences of FTIR spectra obtained during slow (2 mV s{sup {minus}1}) voltammetric sweeps. The reactants studied are formic acid, methanol, ethanol, acetaldehyde, ethylene glycol, glyoxal, and oxalic acid for concentrations between 0.05 and 0.5 M. High coverages ({theta} {ge} 0.4) of adsorbed CO are formed in most cases, as detected from a band at about 1880-1890 cm{sup {minus}1} at the most negative potentials ({minus}0.25 to +0.05 V vs SCE), which is replaced by a band at 2030-2040 cm{sup {minus}1} at more positive potentials. These two features are assigned to C-O vibrations, {nu}{sub CO}, associated with CO adsorbed in bridging and terminal coordination geometries, respectively. The former configuration is apparently engendered by hydrogen coadsorption. For cyclic voltammograms between {minus}0.25 and +0.6 V, the adsorbed CO formed by dissociative reactant chemisorption only undergoes complete electrooxidation during the reverse portion of the potential sweep, at ca. 0.4V. This inability to remove adsorbed CO on ordered Rh(111) appears to be at least partly responsible for the observed weakly electrocatalytic properties of this surface for organic electrooxidations. The production of CO{sub 2} even from formic acid, which occurs readily on Pt(111), does not commence in earnest on Rh(111) until CO is removed during the reverse scan. The electrooxidation of the other reactants on ordered Rh(111) is largely limited to the production of small amounts of CO{sub 2}, although some electrooxidation of acetaldehyde (but not ethanol) to acetic acid is detected. These results are compared with corresponding reactions on ordered Pt(111) and for the electrooxidation of solution CO.

• OSTI ID: 6816317
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:20; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360100* -- Metals & Alloys
360104 -- Metals & Alloys-- Physical Properties
ADSORPTION
ALCOHOLS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DATA ANALYSIS
ELECTROCHEMISTRY
ELEMENTS
ETHANOL
EXPERIMENTAL DATA
HYDROXY COMPOUNDS
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
METALS
METHANOL
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDATION
PLATINUM METALS
RHODIUM
SORPTION
TRANSITION ELEMENTS