From Poorly to Well-Defined Surfaces

Two gronps of electrode materials (electrodeposited platinnm metals and single ciystals) missed each other for a long time, and people simply certified the pronounced difference of electrochemical responses for poly Pt and single ciystals. Some occasions to recognize each other appeared already in XXI century, when a lot of better characterized polyciystalline materials became available. 

Potentials of Zero Charge - Oecasion to Draw Together 

Single ciystal electrochemistiy started to approach surface thermodynamics from attempts to get the basic quantities shown in Fig. 1. Application of a number of already known techniqnes was impossible because the surface areas of single crystals are several orders lower than required for tracing adsorption phenomena by any bulk technique applied to solution (changes of solntion composition resulting from adsorption are negligible even if the volume is veiy low). 

Under these circumstances two principal approaches were possible to increase a sensitivity of techniqnes or to woik ont the alternative tools. The former approach was snccessful only for radiotracer techniques, but their application is Umited to certain ions and is typically helpless for hydrogen adsorption studies. Among alternative (purely electrochemical) techniques, the most successful was surely CO displacement recently reviewed in Ref 72. There are also other probes besides CO (see, e.g., the comparison of CO and N2O probes).  

Another challenge is to widen the knowledge concerning other metals, besides platinum. Good examples of Ru and Ir single crystal electrochemistry were published, but systematic thermodynamic treatment is still absent. 

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