From Fundamental Electrocatalytic Studies to Half-Cell Investigations of Electrode Performance

The major environmental issues linked to fossil fuel utilization, as well as their depletion with time, demand sustainable alternatives for energy conversion and storage. Fuel Cells and Electrolyzers are potential candidates for providing solutions into this direction. Major scientific efforts have been invested during the past decades for improving the catalyst performance, which is defined in an equally important way by its activity and stability. While the catalytic behavior is often studied on a fundamental level at low current densities in a potential region where the mass transport induced error is negligible, the operating conditions in applications consist typically of high current densities with significant mass transport issues. Furthermore the electrochemical interface where the reaction takes place is a confined liquid-metal interface in fundamental investigations, which does not truly represent the so called three phase boundary (tpb) situation at the electrode of a real reactor. In order to bridge fundamental research on electrocatalytic behaviour with the actual applied challenges, we have utilized an alternative experimental tool, namely the Floating Cell. This cell enables the investigation of the electrocatalytic behavior in a broader potential range by overcoming the mass transport issues of the reactant by creating a tpb. In this work we try to demonstrate a step by step approach in the direction of clarifying the particularly complicated regime in the three phase boundary, since for every part of this interface there are numerous parameters, which can have a considerable impact on the catalytic performance. As a result we will discuss the utilization of catalysts in the electrode layer, as well as the potential of this approach for degradation studies and the quick optimization of electrode structures for different reactions in general.