Nb-doped LiBH4 (010) surface for hydrogen desorption: First-principles calculations. (25th May 2015)

• Record Type: Journal Article
• Authors: Yu, Suye; Ju, Xin; Wan, Chubin; Li, Shina
• Is Part Of: International journal of hydrogen energy. Volume 40:Number 19(2015)
• Page Start: 6365
• Page End: 6372
• Publication Date: 2015-05-25
• Subjects: Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2015.03.089
• Languages: English
• ISSNs: 0360-3199

Abstract

<abstract xml:lang="en" abstract-type="author" id="abs0010"> <title id="sectitle0010">Abstract</title> <sec> <p id="abspara0010">Structural, electronic and energetics properties of Nb-doped LiBH<sub>4</sub> (010) surface have been studied based on the first-principles density functional theory calculations. Three kinds of local structures are found during the dehydrogenation reaction of LiBH<sub>4</sub>, the most two favorable hydrogen desorption pathways are found to lead to NbH<sub>2</sub>-BH<sub>2</sub>-(BH<sub>4</sub>)<sub>3</sub> complex when the Nb occupies the top site of single B atom and lead to NbH<sub>2</sub>-(BH<sub>3</sub>)<sub>2</sub> complex when the Nb occupies the bridge site of two adjacent B atoms. The formation of NbH<sub>2</sub> and BH<sub>2</sub> units in the NbH<sub>2</sub>-BH<sub>2</sub>-(BH<sub>4</sub>)<sub>3</sub> complex as well as the catalytic effect of Nb on the structures of surrounding (BH<sub>4</sub>)<sup>−</sup> units due to the orbital overlaps between Nb and inner B-H bonds in the complex. For the NbH<sub>2</sub>-(BH<sub>3</sub>)<sub>2</sub> complex, NbH<sub>2</sub> and NbB<sub>2</sub> phases may be formed in sequence accompanied by the dehydrogenation reaction. The results are in good agreement with the report of Wang, KK et al. experimentally. The calculated average hydrogen desorption energies of Nb-doped LiBH<sub>4</sub> (010) surface are smaller than the pure LiBH<sub>4</sub> (010) surface about 1.7 eV and 1.5 eV, respectively. These properties reveal that the import of Nb has great effect on reducing the bond strength of B-H.</p> </sec> </abstract>