Kinetic measurements of gas-solid reactions, in particular hydrogen-sorption kinetics, were usually interpreted according to single rate-limiting step models. However, recent studies gave clear evidence for the interdependence of fundamentally different steps involved in hydrogen sorption. This interdependence was explored in a one-dimensional continuum model in order to estimate the time, temperature, and pressure dependences of the sorption kinetics and the relevance of several materials parameters involved in the process. Quantitative descriptions of the extraction of physical parameters for various scenarios were given. The model was successfully tested for several experimental cases, ranging from model systems (thin films) to practical systems (LaNi5Hx and MgH2 powder samples).

Interplay of Diffusion and Dissociation Mechanisms during Hydrogen Absorption in Metals. A.Borgschulte, R.Gremaud, R.Griessen: Physical Review B, 2008, 78[9], 094106