Hydrogen voltammograms

Heterogeneous rate constants, 12, 113 Hofmeister sequence, 153 Hybridization, 183, 185 Hydrodynamic boundary layer, 10 Hydrodynamic modulation, 113 Hydrodynamic voltammetry, 90 Hydrodynamic voltammogram, 88 Hydrogen evolution, 117 Hydrogen overvoltage, 110, 117 Hydrogen peroxide, 123, 176... 

Fig. 17. Cyclic voltammogram of the water-soluble Rieske fragment from the bci complex of Paracoccus denitrificans (ISFpd) at the nitric acid modified glassy carbon electrode. Protein concentration, 1 mg/ml in 50 mM NaCl, 10 mM MOPS, 5 mM EPPS, pH 7.3 T, 25°C scan rate, 10 mV/s. The cathodic (reducing branch, 7 < 0) and anodic (oxidizing branch, 7 > 0) peak potentisds Emd the resulting midpoint potential are indicated. SHE, standEU d hydrogen electrode.

It was quickly seen from studies on platinum single crystals that voltammograms for hydrogen adsorption and desorption differ somewhat among the different faces and between the single-crystal faces and polycrystalline platinum. Despite these differences, though, they have common traits as weU. The areas under these curves,... 

Cyclic voltammetry is perhaps the most important and widely used technique within the field of analytical electrochemistry. With a theoretical standard hydrogen electrode at hand, one of the first interesting and challenging applications may be to try to use it to make theoretical cyclic voltammograms (CVs). In following, we set out to do this by attempting to calculate the CV for hydrogen adsorption on two different facets of platinum the (111) and the (100) facets. 

Figure 5.9 Schematic cyclic voltammogram showing the electro-oxidation of the electrode (dashed box). The curve was generated from measurements by Jerkiewicz et al. [2004] of Pt in 0.5 M H2SO4 with a reversible hydrogen reference electrode (RHE). For each separable potential range, an atomistic model of the electrode structure is shown above.

Figure 8.9 Polarization curves for a PtSn/C catalyst recorded by a rotating disk electrode in 0.5 M H2SO4 saturated with either pure hydrogen, a H2/2% CO mixture, and pure CO (the arrow points to the onset of CO oxidation) at 60 °C with 1 mV/s and 2500 rev/min the dashed curve is the cyclic voltammogram (in arbitrary units) in an argon-purged solution at 60 °C with 50 mV/s. (Reprinted with permission from Aienz etal. [2005]. Copyright 2005. Elsevier.)...

Figure 8.13 In situ electrochemical SXS characterization of PtsNi) 11) and Pt(l 11) surfaces (a)XRV measurements forPtsNitlll) at the (0, 0, 2.7) (filled squares) andPt(lll)at (1, 0, 3.6) (open triangles) (b) surface coverage by underpotentially deposited hydrogen (Hupd) and hydroxyl species (OHad) calculated from the cyclic voltammograms (c) segregation profile ascertained from the SXS measurements. (Reprinted with permission from Stamenkovic et al. [2007a]. Copyright 2007. American Association for the Advancement in Science.)...

Figure 12.5 CO stripping voltammogram with a CO- tee 0.1 M H2SO4 electrolyte. Compare the data in Fig. 12.4 the CO oxidation region begins at V = 0.43 V. After CO stripping, hydrogen adsorption/desorption peaks and the beginning of the Pt oxidation range are shown.

The second most widely used noble metal for preparation of electrodes is gold. Similar to Pt, the gold electrode, contacted with aqueous electrolyte, is covered in a broad range of anodic potentials with an oxide film. On the other hand, the hydrogen adsorption/desorption peaks are absent on the cyclic voltammogram of a gold electrode in aqueous electrolytes, and the electrocatalytic activity for most charge transfer reactions is considerably lower in comparison with that of platinum. 

Fig. 5.44 The voltammogram of molecular hydrogen at a rotating bright platinum disk electrode in 0.5 m H2S04, pHl = 105 Pa, 25°C. The rotation speed

Figure 2.17 Cyclic voltammogram of a Pt electrode immersed in N -saturated aqueous sulphuric acid showing the hydrogen adsorption and desorption peaks.

Figure 3.5 Schematic cathodic voltammograms in the hydrogen region. (—) total current,...

Figure 3.8 Current-potential linear sweep voltammogram and the differential reflectivity change in the hydrogen adsorption region at fixed wavelengths (a) 2.34 pm and (b) 1.93 pm. The sweep rate was 15mVs with a square wave modulation of lOmV at 8.5 Hz. From Bewick et al.

Why do we believe that a Cu monolayer is inserted between SAM and gold substrate The 2D-deposit grows and dissolves extremely slowly. Another indication is that the 2D deposit is very stable and shows no displacement by the scanning tip. Cu clusters on top of an alkanethiol-SAM would be only weakly bound and should be easily pushed away by the tip at higher tunnel currents, very much like metal clusters on a hydrogen-terminated Si(lll) surface, which for that very reason are difficult to image by STM (or AFM [122]). And finally, the cyclic voltammograms (Fig. 33) point to the formation of a buried monolayer . 

---