Hydrogen Adsorption on Platinum Single Crystal Electrodes

Abstract

The adsorption of hydrogen on the three main faces (100), (111), and (110) of platinum single crystal electrodes has been studied in 8N H2SO4 at different temperatures with the voltage sweep method. As on polycrystalline platinum electrodes, hydrogen adsorbs on each of the faces in two distinctly different binding states which present themselves as two pronounced maxima in the current‐voltage sweep curves. There are indications for a third binding state giving rise to a third, less pronounced maximum. The potentials at which the maxima occur are essentially the same for polycrystalline and for each of the three single crystal electrodes. However, the relative heights of the maxima are different in each case. The adsorption isotherms and the heats of adsorption are also notably different on the three faces. Under the usual assumption of one hydrogen atom adsorbed per platinum surface atom, initial roughness factors of 1.0–1.9 result which increase to 1.9–2.4 during the experiments. The results suggest that, in fact, each of the crystal faces exposes more than one crystal plane. The left pronounced maximum is assigned to a (110) plane, the right pronounced maximum to a (100) plane, and the third small maximum to a (111) plane. Different proportions of these planes determine the different shape of the curves obtained on the different nominal faces and on polycrystalline electrodes.

The role of defects in the specific adsorption of anions on Pt(111)

“…back to UHV) could be achieved [1][2][3][4]. Although some of these studies employed surface structure analysis by LEED [2][3][4] Since only flame annealed beads had produced this voltammetry, there existed the possibility that unique surface structures were produced during the rapid coding and/or quenching, and that these caused the new electrochemistry [9].…”

Long-range structural effects in the anomalous voltammetry on ultra-high vacuum prepared Pt (111)

“…Early studies of hydrogen and oxygen electrosorption on UHV cleaned and annealed single crystals [1][2][3][4] produced few surprises relative to prior experience with electrochemicallycleaned polycrystalline and single-crystal Pt electrodes [5]. In many of these studies impurities picked up during transfer required the use of electrochemical cleaning before voltammetry was recorded [1,3], use of a non-inert backfill gas [4] and/or Ar+-sputtering of the surface to allow post-electrochemical surface analysis [3].…”

On the Electrooxidation and Amperometric Detection of NO Gas at the Pt/Nafion® Electrode

“…The evolutions of hydrogen and oxygen take place at about E < -0.2 V and E > 1.25 V, respectively. The electrochemical active surface area of platinum was determined from integration of the charge of oxidation of the adsorbed hydrogen region of the stationary CV after subtracting the double layer charge and use 210 µC/real cm 2 as the saturation coverage [31][32][33][34]. The value of Area I, charge of desorbed hydrogen, in Fig.…”