Nanosized Complex of Metal–Ion-Exchanger Composites in the Oxygen Electrochemical Reduction

Abstract

The role of primary (the particles’ size) and secondary (the particles’ content in the material) size effects of metal–ion-exchanger composites in the oxygen electrochemical reduction is elucidated. To this purpose, metal–ion-exchanger particulate composites with different grain size and the metal (Cu) particles’ content are prepared as spherical grains, based on macroporous sulfonic cation-exchange matrix (Lewatit K 2620). X-ray diffraction analysis showed the deposited metal basic particles to be nanosized. A special feature of the metal particles is that during the repeated cycles of their chemical deposition into the ion-exchange matrix pores both the capacity $\varepsilon ,$ and the particles’ radius ${{r}_{0}}$ increased. On this reason, the primary and secondary size effects appeared being interconnected in a common nanosized complex $f = {\varepsilon \mathord{\left/ {\vphantom {\varepsilon {{{r}_{0}}}}} \right. \kern-0em} {{{r}_{0}}}}.$ With the increasing of the capacity the complex increased up to certain limiting value, which is connected with percolation transition from separate metal clusters to collective associates. Correspondingly, the reduced oxygen specific amount also reached its constant value. The oxygen electroreduction process reached quasi-steady-state regime.