The design of high-temperature polymer fuel cells (PEMFCs), e.g. those expected for automotive applications, requires a deep understanding of the electrochemical reactions occurring in the device during operation. Operando electrochemical nuclear magnetic resonance microscopy can constitute a powerful investigation tool to this aim. At present, however, some strong technical limitations, like low sensitivity to less mobile protons, and the limited temperature range of analysis, have bound its use to case models based on perfluorinated membranes operating at high relative humidity and low temperature. By means of a suitable design of the experimental set-up and the use of a new 3D acquisition protocol, we proved the feasibility of electrochemical NMR microscopy on low-water containing polybenzimidazole-based devices, thus allowing full operando characterization of high-temperature PEMFCs, and also paving the way for applications to other electrochemical devices, such as batteries, sensors, supercapacitors, etc.
