V.I. Vigdorovich, L.E. Tsygankova, D.V. Balybin, D.V. Krylski
In purposes of development of ideas about solvent role in the partial electrode reactions, the hydrogen evolution reaction kinetics on iron has been studied in aqueous and water – ethylene glycol (50 wt. % H2O) solutions with х М НC1 + (1 – x) M LiC1 electrolyte composition, containing phenyl biguanidine (FBG). The process proceeds according to Volmer (1) – Tafel (2) mechanism:
Н3О+ + е → Нads + Н2О (1)
Нads + Нads → Н2 (2)
In the background solutions hydrogen evolution reaction (HER) is controlled by discharge reaction (1). FBG insertion into the aqueous solutions in 0,5 – 1,0 mM concentration results a replacement of the limiting stage by the recombination reaction. In the presence of 10 mM of this guanidine derivative the HER rate is limited by the lateral diffusion of adsorbed hydrogen atoms.
In media with mixed solvent, FBG does not influence on the limiting stage character and HER kinetics is controlled by discharge reaction although a nature of solvent molecules solvating discharging proton and metal surface is the same.
Observed regularities are interpreted by the influence of remote cation solvating cover composition.