Tuning the Process Gas in a Dual Plasma Process to Enhance the Performance of Cobalt–Polypyrrole Catalysts for the Oxygen Reduction Reaction in Fuel Cells

Abstract

In this contribution, an improvement to the dual plasma process for producing catalytically active cobalt–polypyrrole-compounds is reported. This is achieved by adding nitrogen, hydrogen and oxygen to the plasma process. The so-obtained compounds were analyzed by Edx, Xrd, Nexafs and Exafs to get information on the structural composition. The structure of the films changes drastically when nitrogen is added to the process gas – the polymeric matrix is more strongly cross-linked and more catalytically active Co–N–C-structures are produced. When hydrogen is added, the structure only changes slightly and using oxygen as a process gas leads to the formation of catalytically inactive cobalt oxides. Furthermore, Cv and Rrde measurements were done to determine the electrochemical properties of the films. It is shown that the catalytic activity increases slightly while the stability of the films can be greatly improved by adding nitrogen to the process.