The large penetration power of high-energy X-rays (>60 keV) raises interesting prospects for new types of structural characterizations of polycrystalline materials. It becomes possible in a nondestructive manner to perform local studies, within the bulk of the material, of the fundamental materials physics properties: grain orientations, strain, dislocation densities etc. In favourable cases these properties may be mapped in three dimensions with a spatial resolution that matches the dimensions of the individual grains. Imbedded volumes and interfaces become accessible. Moreover, the high energies allow better in-situ studies of samples in complicated environments (industrial process optimization). General techniques for research in this energy range have been developed using broad-band angle-dispersive methods, on-line two-dimensional detectors and conical slits. Characterizations have been made at the level of the individual grains and grain boundaries as well as on ensembles of grains. The spatial resolution is presently of the order of 10-100 I, tm. Four examples of applications are presented along with an outlook.

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The cost of polymer electrolyte water electrolysis (PEWE) is dominated by the price of electricity used to power the water splitting reaction. We present a liquid water fed polymer electrolyte water electrolyzer cell operated at a cell temperature of 100°C in comparison to a cell operated at state-of-the-art operation temperature of 60°C over a 300 h constant current period. The hydrogen conversion efficiency increases by up to 5% at elevated temperature and makes green hydrogen cheaper. However, temperature is a stress factor that accelerates degradation causes in the cell. The PEWE cell operated at a cell temperature of 100°C shows a 5 times increased cell voltage loss rate compared to the PEWE cell at 60°C. The initial performance gain was found to be consumed after a projected operation time of 3,500 h. Elevated temperature operation is only viable if a voltage loss rate of less than 5.8 μV h −1 can be attained. The major degradation phenomena that impact performance loss at 100°C are ohmic (49%) and anode kinetic losses (45%). Damage to components was identified by post-test electron-microscopic analysis of the catalyst coated membrane and measurement of cation content in the drag water. The chemical decomposition of the ionomer increases by a factor of 10 at 100°C vs 60°C. Failure by short circuit formation was estimated to be a failure mode after a projected lifetime 3,700 h. At elevated temperature and differential pressure operation hydrogen gas cross-over is limiting since a content of 4% hydrogen in oxygen represents the lower explosion limit.

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