The effect of Ti atom on hydrogenation of Al(111) surface: First-principles studies

First-principles calculations were performed to investigate hydrogen dissociation and subsequent diffusion over both clean and Ti-doped Al(111) surfaces. The calculations show that it is energetically favorable to dope the surface or subsurface layer of Al(111) with Ti atom. Through calculations on the detailed process associated with hydrogen dissociation and diffusion, we found that Ti doping will decrease the hydrogen dissociation barrier by about 0.6 eV. Additionally, the mobility of hydrogen atoms on surface will be easier if Ti atom is placed in subsurface layer instead of top surface layer. The present results further contribute towards understanding the improved kinetics observed in recycling of hydrogen in Ti-doped NaAlH4.