ИСТИНА

Prussian blue analogues (PBA) have garnered intense interest because of their electrocatalytic, electrochromic, ion-sensing and ion-exchange properties. Recently, increased demand for electrochemical energy sources also turned interest in PBA as electrode materials for metal-ion batteries. The crystal structure of PBA allows for the reversible incorporation of a large number of mono- and polyvalent cations, such as Li+, Na+, K+, Cs+, NH4+, Ag+, Zn2+, Mg2+, Al3+ [1]. These unique properties of the systems under study make PBA promising materials for the investigation of still poorly understood intercalation processes. Despite ion and water transport properties of electrochemically prepared PB films have been extensively investigated, charge transfer kinetic patterns were not addressed in earlier studies. Given the possibility for the variation of ionic charge, size, and the structure of ionic solvation shell, PB films may be regarded as unique model systems for the elucidation of the intercalation reaction mechanisms on the molecular level. In this study, we explore the differences in K+, Cs+, Mg2+ and Ca2+ ion transfer rates into AyFe[Fe(CN)6]∙xH2O films in aqueous solutions. The range of selected cations allows for the elucidation of both ion size (contrasting K+ and Cs+), ion charge (K+ and Mg2+) and desolvation energetics (Mg2+ and Ca2+) effects on the intercalation process activation barrier, which provides directly inaccessible information on the reaction pathway [2, 3]. We report the results of voltammetry, potentiostatic intermittent titration, electrochemical impedance spectroscopy and electrochemical quartz crystal microbalance studies, which provide estimates of different contributions to the intercalation activation barrier. References 1. M.A. Malik, P.J. Kulesza, R. Marassi, F. Nobili, K. Miecznikowski, S. Zamponi // Electrochim. Acta. 2004. V. 49, P. 4253. 2. E.E. Levin, S.Yu. Vassiliev, V.A. Nikitina // Electrochim. Acta. 2017. V. 28, P. 114. 3. K. Ogura, M. Nakayama, K. Nakaoka // J. Electroanal. Chem. 1999. V. 474, P. 101.