Speaker
Description
Hydrogen diffusion plays a key role in many materials of high interest for science and society; examples are proton conducting materials for utilization in environment friendly and efficient hydrogen fuel cells, and materials that can store hydrogen or facility important, industrial catalytic processes. However, fundamental questions surrounding the mechanism of hydrogen diffusion and its correlation with the materials’ functional properties, such as proton conductivity and/or catalytic performance, remain to be elucidated for most of these materials. In this contribution, I will report on our recent studies of the mechanistic detail of hydrogen diffusion in two different classes of energy relevant materials, using quasielastic neutron scattering (QENS) together with computer simulations. The first example concerns a study of the brownmillerite type proton conducting oxide Ba2In2O5(H2O), which shows potential for being used as an electrolytic membrane in intermediate-temperature solid oxide fuel cells, whereas the second example concerns a study of the nitride-hydride Ca3CrN3H, which shows promise as a catalyst for ammonia synthesis. The combined analyses of experimental and theoretical data allow us to determine the mechanism of hydrogen diffusivity – stretching from protonic to hydridic species – in both classes of materials, and develop design criteria for new, potentially better performing materials for specific applications.
