Adsorption and Electrooxidation of Carbon Monoxide on Silver

Abstract

The adsorption and electrooxidation of CO on polycrystalline Ag at pH 13, 9.2, 7, and 0.3 have been studied by cyclic voltammetry and Fourier transform infrared spectroscopy (FTIRS). At the four pH values the cyclic voltammograms (CVs) showed the formation and electroreduction of underpotential (UP) Ag oxides, i.e., oxides formed at potentials lower than the equilibrium potential of the Ag/Ag2O couple. Two pairs of peaks of UP oxides appeared at pH 13 and 9.2, but only one pair at pH 7 and 0.3. At pH 13 and 9.2 the current density of the anodic peak of the UP oxide appearing at the more positive potential increased if the solution was saturated with CO, and its peak potential increased (pH 13) or remained the same (pH 9.2), indicating the electrooxidation of adsorbed CO. Both at pH 7 and 0.3 the anodic peak in the presence of CO appeared at potentials 0.2 V more negative than that in the corresponding base electrolyte. Only at pH 13 did the CO adsorbed on Ag remain adsorbed after eliminating the dissolved CO by N2 bubbling, indicating that CO was strongly adsorbed. The FTIR spectra showed, at the four pH values, a band at 1970−2000 cm-1 assigned to CO linearly adsorbed on Ag and, at neutral and alkaline pH, a band at 1860−1900 cm-1 assigned to CO adsorbed in a bridge position. At pH 9.2, 7 and 0.3 there appeared a band at 2048 (pH 9.2 and 7) or 2112 (pH 0.3) cm-1 whose frequency did not change with potential and whose intensity increased with increasing potential and which was therefore assigned to CO adsorbed on an UP Ag oxide.

In Situ Surface-Enhanced Raman Spectroscopy of the Electrochemical Reduction of Carbon Dioxide on Silver with 3,5-Diamino-1,2,4-Triazole

“…[22][23][24][25][45][46][47][48][49] The chemisorption of molecular CO on a metal surface is generally described by the Blyholder model. [22][23][24][25][45][46][47][48][49] The chemisorption of molecular CO on a metal surface is generally described by the Blyholder model.…”

“…In another study, SERS spectra in 0.1 M KHCO 3 revealed two bands near 2130 cm -1 and 2180 cm -1 , attributed to adsorbed CO and [Ag(CO) 2 ] + , respectively. [22][23] This band not only possesses a higher CO stretching frequency than atop-adsorbed CO, but also lacks a significant Stark shift. In addition, several potential-dependent bands were assigned to HCOO -.…”

“…There have been numerous previous studies of CO 2 reduction on Ag in a variety of environments, confirming the metal as an effective CO-producing catalyst. [22][23] Additional features at 2100 cm -1 and 2167 cm -1 were assigned to weakly-held, easily-desorbed CO and CO adsorbed to a partially oxidized Ag surface, respectively. The first Raman spectrum of CO adsorbed to a Ag electrode in aqueous solution showed a band near 2000 cm -1 in 0.1 M KCl or Na 2 SO 4 with a potential-dependence (Stark shift) of approximately 58 cm -1 V -1 .…”

Dealloying to Nanoporous Silver and Its Implementation as a Template Material for Construction of Nanotubular Mesoporous Bimetallic Nanostructures

“…Similar to the AgCl formation in acidic environments, in alkaline conditions, dealloying of AgAl may lead to the formation of thin amorphous Ag(OH) or Ag 2 O layers on the interface. [44,45] The formation of these oxidized silver species on the surface might also inhibit the surface diffusion of Ag atoms and the progressive etching of the Al component, thus resulting in smaller structures.…”

"Desenvolvimento de eletrocatalisadores dispersos para o cátodo de células a combustível alcalinas"

“…As ligas de AgPt/C foram preparadas com diferentes razões atômicas dispersas sobre carbono (AgPt/C), com Ag: [85,86,87,88,89,90]. Resultados e discussão ________________________________________________________________________…”