Rarity Equilibrium Techniques to Study Adsorption

The initial approach to platinum surface thermodynamics was based on mercury-like double layer experience. In particular the adsorption of H ions was treated as purely electrostatic, which means the complete replacement of these ions by any other cations when the latter are in large excess. This assumption works when H cation molar ratio is below 0.1, and valid at least for pH 3 

Rather concentrated set of basic equations was published in a large conference paper and simultaneously in a brief Fmmkin s note. The results of versatile experimental verification of this theoiy were briefly reviewed in Ref 39 and then subsequently in Refs 1-4. Important review of experimental facts collected before the 1960s can be found in Ref 10, Section 4. Finally, the last Fmmkin s book completed and published by Dama.skin and Petrii contains a representative selection of data and the most reliable tabulated values. 

The principal interrelations of the basic quantities are well-known and explained in earlier reviews. The general approach is based on 3D electrocapillary curve, with its two planar intersects corresponding to two Lippmann equations for constant chemical potentials pn = const and pn+ = const, see Refs. 41 3 for additional explanations. Here we mention the most important ratio  

The majority of original results in 1960-70s were reported just for diluted acids with excess salt additives. For pure acid solutions, the important simple link between Qf and p disappeared, and the 

For correct arrangement of these experiments, a lot of routine details had to be controlled, to avoid artefacts. Special cells with separated compartments allowed to replace solutions independently in the chambers of working and reference electrodes, as well as in the bridge between these solutions. Contributions from molecular hydrogen had to be minimized, especially in the vicinity of zero 

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