Scanning Electrochemical Microscopy

To extend the lifespan of polymer electrolyte membrane fuel cells and electrolyzers, it is crucial to understand local degeneration processes in membrane electrode assemblies (MEAs). We developed a spatially resolved analytical method that can differentiate between various functional and structural degeneration phenomena during the aging process of a membrane by combining scanning electrochemical microscopy (SECM) with a diffusion flow cell and using hexacyanidoferrate(II) and protons as redox mediators. One SECM scan at a negative potential detects proton diffusion through the membrane, thereby measuring its proton conductivity. A second SECM scan at a positive potential visualizes iron complex diffusion through the membrane, highlighting perforating structural damage, such as cracks and holes. This method has been successfully validated for spatially resolving membrane damage following various aging tests.