Hydrogen Electrode Reaction: a General Description of the Equilibrium polarization resistance

C.A. MAROZZI; M.A. MONTERO; M.R. GENNERO DE CHIALVO; A.C. CHIALVO

Buenos Aires

Congreso; 20th Topical Meeting of the International Society of Electrochemistry (ISE): Advances in Lithium and Hydrogen Electrochemical Systems for Energy Conversion and Storage; 2017

ISE

The equilibrium polarization resistance (Rp) is an experimental parameter that contains valuable kinetic information and can be evaluated directly and precisely. On metal electrodes the hydrogen electrode reaction (HER) is verified in both, alkaline and acid solutions, through the mechanism of Volmer-Heyrosky-Tafel (VHT). It shows a strong diffusion contribution of the molecular hydrogen in the anodic potential region, which turns to be negligible for cathodic overpotentials greater than 0.15 V, being significant around equilibrium potential. Moreover, Rp is widely used to evaluate the exchange current density (jo), although it is distorted by the diffusion contribution. In previous studies carried out considering Langmuir adsorption isotherm, the equation for the variation of Rp on the limiting diffusion current density (jL) was derived. In this context, it is carried out the derivation of a general dependence Rp(jL), independent of the description of the adsorption process of the reaction intermediate.