Vacancy mediated desorption of hydrogen from a sodium alanate surface: An ab initio spin-polarized study

摘要

Ab initio spin-polarized density functional theory calculations are performed to explore the effect of single Na vacancy on NaAlH_4(001) surface on the initial dehydrogenation kinetics. The authors found that two Al-H bond lengths become elongated and weakened due to the presence of a Na vacancy on the NaAlH_4(001) surface. Spontaneous recombination from the surface to form molecular hydrogen is observed in the spin-polarized ab initio molecular dynamics simulation. The authors' results indicate that surface Na vacancies play a critical role in accelerating the dehydrogenation kinetics in sodium alanate. The understanding gained here will aid in the rational design and development of complex hydride materials for hydrogen storage.