Effects of transition metal Ti and its compounds on hydrogen adsorption performance of Mg17Al12

Abstract

Catalytic effects of Ti, Ti n (n = 2–4), TiC, and TiO 2 clusters on hydrogenation of the Mg17Al12(110) surface were investigated by using density functional theory. The geometry structure, adsorption energy, dissociation barrier, density of state, electron density, and electron density difference were calculated. As a result, the adsorption energy and dissociation barrier of hydrogen on the Ti-containing Mg17Al12(110) surfaces were effectively improved as compared with the clean Mg17Al12(110) surface. Such as the adsorption energy of H(H2) on the Mg17Al12(110) surface was −0.18 (−0.13) eV, while the related energy of H(H2) on the Mg17Al12(110)/TiO2 system was −1.50 (−1.22) eV. In addition, H2 molecules could be spontaneously dissociated to H atoms on the Mg15Ti2Al12(110), Mg17Al12(110)/Ti3, and Mg17Al12(110)/TiO2 surfaces. The results of electronic structures indicated that the H s states principally hybridized with the Ti s and d states. The mechanism of Ti, Ti n (n = 2–4), TiC, and TiO2 clusters on the promoted hydrogenation of Mg17Al12 was explained. • H 2 adsorption and dissociation on Ti-containing Mg 17 Al 12 (110) surfaces are studied. • Enhancement of hydrogenation for Ti-containing Mg 17 Al 12 (110) surfaces. • Catalytic effects of TiO2 on the hydrogen adsorption are better. • Ti and TiO 2 play important roles in dissociating hydrogen.