A H2/O2 Fuel Cell for In situ μ‐Raman Measurements. In‐depth Characterization of an Ionic Liquid Filled Nafion Membrane

Abstract We report the design of a H 2 /O 2 (fuel) cell for in situ μ‐Raman spectroscopic measurements. The horizontal orientation of the cell is conceived to allow the penetration of the laser beam along the z‐axis from one electrode to the other. We show that during in‐depth analyses the Raman signal is not significantly lost and the axial resolution is sufficiently good to allow quantitative and qualitative spectral interpretation. We report “proof of principle” tests performed on Nafion membranes swelled with protic ionic liquids to demonstrate the validity of the design and the potentiality of the method. Our results confirm that this experimental setup can efficiently be used to follow structural changes and concentration gradients in the electrolyte of a fuel cell operando . In particular, we have been able to resolve both in time and in space the hydration state of the membrane as well as spatial variations for the $ {\rm SO}_3^- $ coordination shell during a compositional transient state.