Plasma deposited thin-film sandwich-like bifunctional electrocatalyst for oxygen reduction and evolution reactions

The thin-film sandwich-like system consisting of catalytic films and highly electrically conductive films arranged alternately one on top of the other was prepared using the cold plasma deposition method. The catalytic films were based on cobalt oxide while the electrically conductive carbon-nitrogen films were produced from acrylonitrile. The electrocatalytic activity of the system was tested for both the oxygen reduction reaction (ORR), on O2 gas, and the oxygen evolution reaction (OER), from H2O2. Studies on the molecular structure showed that the catalytic films contained only a fraction of CoO without Co3O4 spinel. It was found that the catalytic activity of the sandwich-like system, for both the ORR and OER, was a several-fold higher compared with a film containing the same amount of the catalyst without the conducting films. It confirms the predictions on the possibility of increasing the catalytic activity by constructing the sandwich-like systems.