Influence of o-fluorophenylbiguanidine on the kinetics of hydrogen evolution reaction on iron, the nature of rate-determining step and hydrogen diffusion through a steel membrane

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• 作者：V.I. Vigdorovich^a ; L.E. Tsygankova^b ; ^{vits21@mail.ru} ; D.V. Balybin^b ; V.I. Kichigin^c
• 关键词：Iron ; o-Fluorophenylbiguanidine ; Hydrogen ; Discharge ; Adsorption ; Recombination
• 刊名：Journal of Electroanalytical Chemistry
• 出版年：2013
• 出版时间：15 January, 2013
• 年：2013
• 卷：689
• 期：Complete
• 页码：117-123
• 全文大小：507 K

文摘

It is shown, hydrogen evolution reaction (HER) on iron occurs according to Volmer-Tafel mechanism in acidic aqueous chloride solutions with constant ionic strength. Relation between o-fluorophenylbiguanidine (o-FPBG) concentration and the kinetics and the nature of rate-determining step (rds) of hydrogen evolution reaction (HER) on iron in acidic chloride media with constant ionic strength has been established. Kinetic parameters of HER - dE/dlog i_c, dE/dlog C_H+, (dlog i_c/dlog C_H+)_E, d¦Ç/dlog i_c, d¦Ç/dlog C_H+ and (?log i_c/?log C_H+)_¦Ç - have been obtained at different concentrations of o-FPBG and compared with theoretical values appropriate to Volmer-Tafel mechanism. An increase in the o-FPBG concentration provokes sequential change of the rds in the hydrogen evolution reaction according to scheme: slow discharge - slow recombination - slow surface diffusion - slow discharge. It is proved that in the background solutions the slow discharge is followed by chemical recombination, but hydrogen diffusion rate through a steel membrane practically does not depend on the rds nature. Observed phenomena are interpreted from a position of existence of two adsorbed hydrogen forms - subsurface and raised above the surface - and difference in surface coverage by either of them.