On the barriers limiting the reaction kinetics between catalysed Mg and hydrogen

The rate-limiting step of the hydriding of catalysed Mg has been ascertained through a key experiment in which the density of nuclei of the product phase was artificially modified. The various microstructures observed allow accurate identification of the reaction rate-limiting step for different hypotheses. The experimental work was based on kinetics analysis coupled with scanning electron microscopy metallographic observation. It is found that the reaction barrier is located at the external surface of the powder particles, suggesting decoration with catalyst as a possible solution.