Molecular orientation of hydroquinone on smooth platinum electrodes studied by radioactive labeling

Hydrogen-assisted and CO-assisted reductive desorption of hydroquinone-derived adlayers from Pt(111) single crystal electrodes

“…However, the sharp reduction peak centered at 0.065 V, previously ascribed to the direct reductive desorption of Q (ads) from well-ordered Pt (1 1 1), is not observed. The voltammetry at disordered Pt(1 1 1) electrodes is reminiscent of that reported for poly Pt by Krauskopf et al [21]. Fig.…”

“…The resulting adsorbed monolayers have been investigated [20][21][22][23] using STM, LEED, AES, HREELS, FTIR and electrochemistry. In spite those efforts, the chemical identity of Q (ads) is still a subject of controversy [23].…”

“…In fundamental studies, well-ordered Pt(h k l) single crystal electrodes have received most of the attention; having been one of the most commonly used materials for the construction of solid electrodes. Like CO, that served as a model chemisorbate in the study of gas-solid heterogeneous interfaces, H 2 Q and related quinonoid moieties have served as prototypical organic chemisorbates in what is now an increasing body of work at solid-liquid electrode interfaces [20][21][22][23][24]. From an analytical standpoint, their richness in reactivity makes them promising probes of chemical reactivity at electrode solution interfaces.…”

Molecular Orientation of Hydroquinone Adsorbed at a Platinum(111) Thin-Layer Electrode

“…Furthermore, adsorption of HQ on electrochemically disordered polycrystalline Pt and singlecrystal Pt(111) surfaces showed higher packing densities than on annealed polycrystalline Pt and ordered Pt(111) surfaces, respectively, but part of the increase was believed to be due to an increase of the electrode surface area (6). In addition, radiotracer methods found a large difference between the packing densities at low and high HQ concentrations (11), but according to those authors an "unidentified systematic error" made it difficult to compare the results with those of other methods. In general, questions of reorientation also exist for many of the other molecules that have been studied, although more and more evidence indicates that reorientation is a characteristic of molecules having certain types of molecular structure.…”

A DEMS study of the electrocatalytic hydrogenation and oxidation of p-dihydroxybenzene at polycrystalline and monocrystalline platinum electrodes

“…When chemisorption proceeds from diluted H 2 Q solutions (C < 0.10 mM) flat-oriented species (g 6 ) is formed; whereas for solution with concentrations higher than 1.0 mM, edgewise-oriented species (g 2 ) are formed. These orientational assignments have been verified using independent techniques such as infrared reflection-adsorption spectroscopy (IRAS) [18] and radiochemistry [19]. Studies on H 2 Q chemisorption at well-defined Pt(111) surfaces have been reported as well [20,21].…”