An in Situ Infrared Study on the Effect of pH on Anion Adsorption at Pt(111) Electrodes from Acid Sulfate Solutions

Abstract

From the in situ FTIR spectroscopy of the electrode/electrolyte solution interface at pH values of 1.2, 2.0, and 3.4, it can be confirmed that the adsorbate associated with the anomalous peaks in the cyclic voltammetry of Pt(111) in sulfate-and bisulfate-containing solutions is not the sulfate anion. The structure of the bisulfate-like adsorbate is tentatively postulated to be a sulfate ion/hydronium ion ion pair: SO 4 2-‚H3O + . Over the potentials in question, and only in solutions with appreciable HSO4 -concentration, can IR bands be found that are associated with the adsorbed species.

In SituFourier Transform Infrared Measurements of Sulfate Adsorption on Hematite in Aqueous Solutions

“…4b and those in Fig. 5b are to ú95% due For IR/spectra, Lorenztian or Gaussian lineshapes, or mixto adsorbed SO 20 4 .…”

“…Results from various studies with cesses; e.g., it slows ligand promoted dissolution of iron dried samples are discussed below. FTIR studies of sulfate oxides (2), alters the activity of catalysts (3), and changes adsorption on metal electrodes in aqueous solutions used electrode properties (4). Questions about the mechanism of potential difference infrared spectroscopy (PDIR), a more sulfate adsorption and the structure of sulfate surface com-sensitive technique applicable to conducting electrode surplexes remain.…”

“…These PDIR studies were concerned with sulfate or been conclusively resolved: (1) Is sulfate adsorbed as an bisulfate adsorption on electrode surfaces such as Pt at low inner-sphere or an outer-sphere complex? (2) Is the structure pH (4,9). To our knowledge, no IR studies of sulfate adsorpmono-or bidentate?…”

First principles study of sulfuric acid anion adsorption on a Pt(111) electrode

“…The latter mode is infrared inactive for free sulfate ion (T d symmetry) but becomes active by the adsorption owing to the symmetry reduction to pseudo-C 3v . The symmetry reduction also splits the triply degenerate S-O stretching modes at 1104 cm -1 for free sulfate ion 13,90,91 into three separate modes at 1250, 1020, and 997 cm -1 . The dynamic dipole moments of the latter two modes are nearly parallel to the surface (Fig.…”

Methanol tolerant oxygen-reduction activity of carbon supported platinum–bismuth bimetallic nanoparticles

“…The higher ORR current in sulphuric acid medium is attributed to the adsorption of the bisulphate ion (HSO 4 -), a tetrahedral anion which adsorbs strongly on Pt(111) [56] which results in inhibitory effects of PtOH, a factor favourable for ORR. In perchloric acid, bismuth dissolves from the electrode surface during cycling and may interact with the perchlorate anion.…”