Redox reactions of [Ru(NH3)6]2+/3 +, [Fe(CN)6]3-/4- and Fe2+/3+ on pristine and electrochemically modified carbon nanowalls under physical adsorption of compounds with the skeletalsand macrocyclic structure

For pristine (P-CNWs) and functionalized (F-CNWs) carbon nanowalls (CNWs), the effect of physical adsorption of certain compounds with the skeletal structure of bicyclic molecules (camphor, borneol) and also of macrocyclic compounds (Na+ complexes of cryptand 222 (cryptate) and cucurbit [7]uryl) on the kinetic parameters of redox reactions aRu(NH3)6](2+/3+),[Fe(CN)6](3-/4-) and Fe2+/3+) has been studied systematically for the first time by the methods of cyclic voltammetry. It is shown, that the adsorption of these compounds on F-CNWs does not change the rate constants k(0) of [Ru(NH3)6](2+/3+) and IFe(CN)6](3-/4-) redox reactions, whereas their adsorption on P-CNWs leads to a decrease in k by the factor 2.5-10. For the Fe2+/3+ reaction at the presence of organic compounds under study, the effect of inhibition is observed for P-CNWs and for F-CNWs, though to the lesser extent. The diametrically opposite effects of the adsorption of camphor and borneol on the kinetics of this reaction are observed with the transition from the pristine to functionalized electrode surface. It is shown, that the adsorption of two-dimensional condensed layers of camphor and borneol on the atomically smooth mercury surface, induces a decrease in k for [RU(NH3)6](2+/3+) reaction, substantially more pronounced, as compared to P-CNWs (by the factor of 25 and 40, respectively). This difference can be explained by the peculiarities of the topology of carbon nanowalls which determines the preferential occurrence of the redox reactions on the edges of basal planes where the formation of condensed layers by the skeletal and macrocyclic molecules seems to be complicated. (C) 2017 Elsevier B.V. All rights reserved.