Prehistory and Visible Horizon

Electrochemistry of other platinum group metals was also roughly characterized before 1960s (see, e g.. Refs. 13-15 for Rh 

When the fact of hydrogen adsorption on platinum metals was well documented, a search for self-consistent models started, aimed to description of surface hydrogen coverage dependence on electrode potential and temperature. Breiter was the first who studied the temperature dependence of hydrogen adsorption on smooth platinum, rhodium and iridium. He demonstrated a possibility to present experimental dependences typical for polycrystalline platinum by combination of two Fmmkin isotherms (see below in Section IV. 5). 

The data on coverage-dependent differential heat of hydrogen adsorption and coverage-potential dependences formed a set of the most early quantitative thermodynamic information reported for both smooth platinum metals and electrodeposited dispersed Pt, Rh, and Ir in acidic and alkaline solutions. The following tendencies appeared to be general  

The particular disagreements found for the behavior of two forms of hydrogen at smooth and dispersed platinum were probably induced by a limited accuracy of data treatment, as well as by still not exactly proven assumption of complete coverage at zero RHE potential. 

Looking back one can easily notice that before mid 1960s the thermodynamics of adsorption phenomena on platinum was considered mostly in terms of temperature dependence. This traditional approach was not specific for electrochemical thermodynamics, but there was no serious basis to involve other parameters. Another remarkable point is discussion exclusively in terms of hydrogen adsorption, imder more or less transparently formulated assumption of complete charge transfer with formation of uncharged adatom. It is shghtly strange future surface thermodynamics was outlined already in 1936, and its principal point was the interplay of ionic and atomic adsorption, but even 30 years later ionic contribution was still accounted only as very formal subtraction (double layer correction). When the idea of this interplay was first presented by Frumkin in more comprehensive form, it met immediately Breiter s support.  

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