Fundamental studies of H2 interaction with MAl3 clusters [M = Li, Sc, Ti, Zr]

JOURNAL OF ALLOYS AND COMPOUNDS

卷:588

Article

Samolia, Madhu¹  Kumar, T. J. Dhilip¹ 

[1] Indian Inst Technol Ropar, Dept Chem, Rupnagar 140001, India

关键词: Hydrogen storage materials;    Complex metal hydrides;    Density functional theory;    H-2 Adsorption;   

DOI  :  10.1016/j.jallcom.2013.10.147

来源: Elsevier

【 摘 要 】

Complex metal hydride is a promising hydrogen storage material for automobile applications due to its reversible storage capacity. The presence of transition metal halide is found to improve significantly the kinetics of H-2 adsorption and desorption processes. Experimental studies have indicated the formation of distorted MAl3 phase where M = Sc, Ti, Zr. In this study, a first-principles density functional study has been performed to investigate the hydrogen interaction and saturation on stable tetrahedral MAl3 clusters [M = Li, Sc, Ti, and Zr] by employing spin-polarized hybrid and non-local density functionals. On saturation, the first H-2 molecule undergoes chemisorption in the transition metals while further loading results in physisorption with the Kubas-type H-2 interaction. Activation energy barrier for the H-2 dissociation over the cluster is calculated to be similar to 0.2 eV for the transition metals. Effect of external electric field on the MAl3H4 cluster with molecular H-2 is studied which leads to polarization of physisorbed H-2 and the cluster. The results offer an explanation for catalysts role in improving the kinetics of H-2 sorption process in complex metal hydrides. (C) 2013 Elsevier B. V. All rights reserved.

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