Effect of Catalytic Poisons upon the Individual Step Rates

Effect of Catalytic Poisons upon the Individual Step Rates 

Stonehart and Kohlmayr investigated the HER rate on a rotating Pt bead electrode as a function of surface coverage with CO. They concluded that the electrocatalytic activity of Pt for the hydrogen ionization is a quadratic, but not a linear, function (1 - poison) of the free surface fraction, thus suggesting a rate-determining dual-site step, probably the Tafel reaction. However, this correlation was questioned later by Breiter.  

In a series of interesting papers by members of the Polish school, the effect of additives upon the improvement of the hydrogen-absorbing property of Ni 2i4-2i6) pg(2i7) during cathodic hydrogen evolution was 

14a) was found to be a typical substance which retards strongly the overall HER rate but not that of the Tafel step. It therefore retards the Volmer step 

The overpotential transient experiments on Pd thus provide a convenient means for investigating effects of various surfactants upon elementary processes rather than on the overall reaction. Hopefully, Investigations along these lines will offer characterization of surfactant effects on electrocatalytic processes such as those involving corrosion inhibitors and effects of additives on electroreduction processes, etc. 

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