Calculating Reversible Potentials for Pt−H and Pt−OH Bond Formation in Basic Solutions

Abstract

Two redox reactions on platinum electrodes in base, the formation of underpotential deposited hydrogen, forming a Pt-H bond, and the electro-oxidation of water, forming a Pt-OH bond, were studied by two methods. The first applies a linear relationship between reaction energy in solution and standard reversible potential, an approach recently used in this lab to predict the formation potential of the surface-bonded species. This method depends on the availability of accurate surface adsorption bond strengths from measurement or theory and can be applied in two formats, the empirical model and the linear correlation model. The second method treats the reaction within the so-called double-layer model where reactants and products on the surface are well defined and are experiencing the influence of the electrolyte. When this approach is used, two coordination shells of hydrogen bonded water molecules are found necessary to sufficiently stabilize the hydroxide ion in this model, unlike acid for which past work showed only one shell around the hydronium ion is needed. The calculated reversible potentials for both reactions by the empirical and linear correlation models are in good agreement with the experimental onset potentials observed in cyclic voltammetry measurements for Pt(111) surface electrodes when empirical or accurately calculated H, OH, and H(2)O adsorption energies are used. The double layer models for these reactions also yield satisfactory results, and it is concluded that the models should be useful for studying electron-transfer reactions in base, as has already been done for forming Pt-H and Pt-OH in acid solution.

Irregular-shaped platinum nanoparticles as peroxidase mimics for highly efficient colorimetric immunoassay

“…The formed Pt H bonds might be hindered the reaction between H 2 O 2 and ISPtNP (Scheme 1), thus resulting in the decrease of catalytic efficiency of the ISPtNP. After the assynthesized ISPtNP were immersed into the alkaline solution, the partially formed Pt OH bonds did not greatly influence the reaction between H 2 O 2 and the ISPtNP [31,[45][46][47]. So, the catalytic efficiency of the pretreated ISPtNP in the basic solution could be almost maintained at the normal level toward TMB/H 2 O 2 .…”

“…4b). This is most likely a consequence of the fact that the Pt H bonds were easily formed on the surface of the ISPtNP at the acidic solution [31,[45][46][47]. The formed Pt H bonds might be hindered the reaction between H 2 O 2 and ISPtNP (Scheme 1), thus resulting in the decrease of catalytic efficiency of the ISPtNP.…”

Hydrogen production by alkaline water electrolysis

“…Accordingly, many studies are progressively revealing the atomic-level details of the electrode reactions at water electrolysis cells. [122][123][124][125] Early electrolysis cells were about 60-75% efficient. However, the current small-scale, best-practice figure is close to 80-85%, with larger units being a little less efficient (ca.…”

Electrochemical reactions at the electrode/solution interface: Theory and applications to water electrolysis and oxygen reduction

“…They concluded that the H 2 O (H 2 O ad → OH ad + H ad ) and OH (OH ad → O ad + H ad ) homolytic cleavage is unlikely to occur below 0.6 V due to the high reaction barrier (1.35 eV) [88]. They utilized the local reaction center model to investigate the OH ad formation in the acid and base solutions [57,93]. In the latter, water split to hydroxyls through an oxidative deprotonation pathway: H 2 O ad → OH ad + H + + e  (U) [57].…”