Use of Model Pt(111) Single Crystal Electrodes under HMRDE Configuration To Study the Redox Mechanism for Charge Injection at Aromatic/Metal Interfaces

Abstract

The electrochemical reactivity of hydroquinone-derived, catechol-derived and benzene-derived adlayers is compared at Pt(111) single-crystal surfaces (i) under stagnant hanging meniscus (HM) configuration and (ii) under hydrodynamic conditions imposed by combining the HM configuration with the rotating disk electrode (RDE) that merge in the so-called HMRDE technique. For the three cases studied, the results suggest that reductive desorption of the adlayers can be accomplished in aqueous 0.5 M H(2)SO(4) solutions within the time frame of a single cathodic scan, i.e. the first half of a single CV experiment. The results highlight the simplicity of exploiting the hydrodynamic conditions imposed by RDE as a convenient electroanalytical strategy to elucidate controversies regarding whether desorption takes place or not during electrode processes studied under the HM configuration.

Assemblies of polyvinylpyrrolidone-capped tetrahedral and spherical Pt nanoparticles in polyelectrolytes: hydrogen underpotential deposition and electrochemical characterization

“…H upd at the PVP-Pt NP electrodes occurred in a major H(W) adsorption state and a minor H(S) state. Results showed that H upd was modified by PVP binding on the Pt NP reminiscent of the effect of adsorbed organics on single crystal Pt electrodes, and are interpreted in light of two hypotheses in the literature, the first attributing the modified electrochemical process to H adsorption accompanied by desorption of the organic layer 47,48 and the second hypothesis ascribing the process to H upd occurring on a Pt surface modified with an organic adlayer, 49,50 with evidence of the absence of PVP desorption. PVP-binding on the Pt NPs was also found to block surface oxidation and O 2 evolution, different from the effect of polyacrylate-capping of Pt NPs.…”

“…Adsorption of organic molecules such as benzene, quinone, catechol, urea and oxalic acid on Pt(100), (111), or (110) and stepped surfaces has been reported to modify H upd at the Pt planes. [47][48][49][50][55][56][57][58][59] Two hypotheses have been proposed to explain oxidation/reduction peaks appearing in the H upd region…”

“…In the first following the work of Itaya et al on benzene adsorption at Pt(111), the modified electrochemical process was proposed to consist of desorption of the adlayer accompanied by H upd . 47,48 In the second hypothesis put forth by Jerkiewicz et al studying benzene adsorption on Pt(111), 49 the authors contested desorption of the adlayer, and that H upd takes place on the adlayer-modified Pt surface, first on 3-fold coordinated sites between benzene molecules and then in subsurface sites, with benzene modifying the Pt-H bond energy. 49 H upd characteristics of the Pt clean surface were shown to be recovered by continued potential cycling in organic free electrolytes.…”

“…49 H upd characteristics of the Pt clean surface were shown to be recovered by continued potential cycling in organic free electrolytes. 49,55,56 According to these hypotheses, the main reduction peak denoted H(W) could be ascribed either to PVP desorption accompanied by H upd , 47,48 or to H upd on a PVP-modified surface. 49 A marked difference from studies of organic adlayer modified Pt is that the H(W) peak did not decrease upon continued cycling, which indicates the absence of irreversible desorption during potential cycling even into the H 2 evolution region.…”

Electrochemical Generation of Mesopores and Residual Oxygen for the Enhanced Activity of Silver Electrocatalysts

“…However, many practical devices such as Zn–air batteries employ highly concentrated electrolytes, in which the ORR kinetics may differ from that in dilute electrolytes. Therefore, we tested the ORR performances of AgO δ /CP and Ag/CP electrodes in a hanging meniscus configuration (Figure S6), which allows atmospheric oxygen to diffuse through the triple phase boundary (TPB). − …”