Hydrogen Adsorption Behavior

The research on hydrogen underpotential deposition (UPD) at electrodes has identified the Gibbs energy of H-binding on the surface () and the half-bond 

At a potential of E, the proton concentration of Ch+, and a surface H coverage of 0, the fraction of surface vacant site can be expressed as 1-. The simplest electrochemical thermodynamic relation can be expressed as a function of the electrode potential  

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Completely different behavior is observed with S and Se, as shown in Fig. 7.8. With these adatoms, deposition on the terrace starts from the very beginning and no selectivity towards the step is observed. Additionally, deposition of the adatom changes the hydrogen adsorption energy on the (110) step sites, as reflected by the progressive shift of the peak at 0.12 V towards higher potential values. 

Hou, P.X., S.T. Xu, Z. Ying, Q.H. Yang, C. Liu, H.M. Cheng, Hydrogen adsorption/desorption behavior of multi-walled carbon nanotubes with different diameters. Carbon 41,2471-2476,2003. 

The differences in time-dependent adsorption behavior between 99% PVAC at 25° and 50°C demonstrate the influence of intra- and intermolecular hydrogen bonding in the adsorption process. The limiting surface pressure of the hydrophobic water-soluble polymer appears to be 33 mN/m, approximately 7 mN/m below that of commonly used surfactants. The rate of attainment of equilibrium surface pressure values is faster if there is uniformity of the hydrophobic segments among the repeating units of the macromolecule. 

The investigation of adsorption phenomena occurring on Pt and Pd electrodes is an important task for the clarification of their behavior in electrocatalytic processes. A characteristic feature for these systems is the hydrogen adsorption reflected by the shape of voltammetric curves taken under suitable conditions. This experimental approach constitutes the intersection point where the problem of perchlorate... 

The current-potential behavior shown in Figure 5.22 is claimed to be characteristic of a clean platinum surface in a clean test solution,99 and can be used as a criterion of solution and electrode cleanliness in aqueous 0.5 M H2S04. The presence of organic material generally will cause a decrease in the hydrogen adsorption peaks and the appearance of new peaks. 

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