B3LYP and in Situ ATR-SEIRAS Study of the Infrared Behavior and Bonding Mode of Adsorbed Acetate Anions on Silver Thin-Film Electrodes

Abstract

The adsorption of acetate anions on silver thin-film electrodes has been studied by in situ infrared spectroscopy experiments and density functional theory calculations. Stable silver thin films were deposited either chemically or by argon sputtering on germanium and silicon substrates, respectively, and used as electrodes under internal total reflection conditions (ATR-SEIRAS) with a Kretschmann configuration. B3LYP harmonic IR frequencies of acetate species adsorbed with different geometries on Ag clusters with (111), (100), and (110) orientations have been calculated using LANL2DZ ECP and 6-311++G** basis set. The theoretical and experimental results confirm that bonding of acetate to the surface involves the two oxygen atoms of the carboxylate group, with the O−C−O plane perpendicular to the metal surface. The calculated frequencies reveal that the surface crystallographic orientation and total charge have little effect on the vibrational frequencies of adsorbed acetate species.

Spectroelectrochemical Study of the Photoinduced Catalytic Formation of 4,4′-Dimercaptoazobenzene from 4-Aminobenzenethiol Adsorbed on Nanostructured Copper

“…[41][42][43] In the same way, we do not expect to have a significant effect of surface orientation on the vibrational bands of adsorbed 4-ABT and 4,4'-DMAB species. In addition, the small cluster size is not expected to significantly affect the calculated frequencies, as this is a local property.…”

Glycolate adsorption at gold and platinum electrodes: A theoretical and in situ spectroelectrochemical study

“…As mentioned above, the ATR-SEIRAS experiments provide also information on the potential-dependent water-metal and water-adsorbate interactions [30,39,40]. In this respect, the in situ ATR-SEIRA spectra showed the existence of weak acetate-water interactions in agreement with bidentate bonding of adsorbed acetate and with the hydrophobic character of the methyl group [12,15,16,36,37]. In the case of the fluoroacetate anions, the ATR-SEIRA spectra show the existence of non-hydrogen bonded water molecules coexisting with the adsorbed anions, in an extent that depends on both the fluoracetate coverage and the number of fluorine atoms in the fluoroacetate anion [38].…”

“…This choice is based on the (1 1 1)-like character of the gold thinfilm electrodes used in this work, as well as on the absence of significant effects of the surface crystallographic orientation on both the experimental and calculated band frequencies for carboxylate anions adsorbed on metal electrodes [16,36,38]. On the other hand, previous studies on the adsorption of acetate at gold clusters showed that, when starting from unidentate bonding, the acetate was prone to go towards the cluster border or to desorb [36].…”

“…Among others, the electrochemical behaviour of anions coming from carboxylic acids has been studied in the last years as a model for adsorption and reactivity studies at metal electrodes [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In the case of dicarboxylic acids, the weak acidic character of their anions allows their use as probe species for testing the acid-base properties of the electrode surface [10,14,17,18].…”

“…In previous papers we reported on the adsorption of acetate anion [12,15,16,36,37] and its fluoro derivatives [38] on gold [36][37][38] and silver [12,15,16] thin-film electrodes as well as on gold single crystals [36], studied by combining cyclic voltammetry with external reflection (using gold single crystals) and Surface Enhanced Infrared Reflection Absorption Spectroscopy experiments under attenuated total reflection conditions (ATR-SEIRAS, with gold and silver thin films) measurements. The analysis of the spectra of adsorbed (fluoro)acetate anions was carried out on the basis of the theoretical harmonic vibrational frequencies and intensities obtained from B3LYP calculations for the anions adsorbed with different geometries on Au and Ag clusters with the basal surface orientations.…”