Dissociation and Sticking of H₂ on Mg(0001), Ti(0001) and La(0001) Surfaces

Abstract

We performed quantum dynamics calculations using previously obtained potential energy surfaces (PESs) for the dissociative adsorption of hydrogen molecule incident on a Mg(0001), Ti(0001), and La(0001) surface. Based on the sticking probability plots we obtained as functions of the incidence H₂ beam energy, La is the best material for hydrogen storage, followed by Ti, and then by Mg. This is due to the absence of an activation barrier in the H₂/La(0001) system. Both H₂/Ti(0001) and H₂/Mg(0001) systems have activation barriers, but the H₂/Ti(0001) system has a very small activation barrier far from the curved region of the reaction path, while the H₂/Mg(0001) system has a high activation barrier close to the curved region along the reaction path. Our results also indicate that the sticking probability has some dependence on the vibrational state of the impending H₂ molecule for the Mg, Ti and La surfaces. The degree of dependence still varies in each metal. Vibrational effect is most observed with Mg, followed by Ti, and then by La.