Structure of alkaline aqueous NaBH4 solutions by X-ray scattering and empirical potential structure refinement

doi:10.1016/j.molliq.2018.10.124

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	Structure of alkaline aqueous NaBH4 solutions by X-ray scattering and empirical potential structure refinement
	Zhou, Yongquan; Yamaguchi, Toshio; Yoshida, Koji; Fang, Chunhui; Fang, Yan; Zhu, Fayan
	2019-01-15
发表期刊	JOURNAL OF MOLECULAR LIQUIDS
ISSN	0167-7322
卷号	274 页码:173-182
摘要	Structure of alkaline aqueous NaBH4 solutions at NaBH4 concentrations of 1.0 to 9.1 mol.dm(-3) (almost saturated) as well as a 1.3 mol.dm(-3) NaOH solution was studied by X-ray diffraction and Empirical Potential Structure Refinement (EPSE) modelling. In the 1.0 mol.dm(-3) alkaline NaBH4 solution, Na+ is surrounded by around six water molecules with octahedral geometry. With an increase in NaBH4 concentration, the hydration number of Na+ decreases from 4.8 +/- 1.1 at 2.25 mol.dm(-3) solution to 2.9 +/- 1.3 at 9.1 mol.dm(-3) with an almost constant Na+-O (W:H2O) distance of 2.34 angstrom. The decrease in hydration number for Na+ is compensated by the formation of ion pairs between Na+ and BH4- to ensure an octahedral hydrated geometry for Na+. About 6.0 +/- 1.6 water molecules are likely to bond to BH4- via tetrahedral edges or tetrahedral corners without a very specific hydration geometry, giving rise to each hydrogen atom of BH4- bound to 2.3 +/- 1.0 water molecules through dihydrogen bonds. The hydration number around BH4- decreases with increasing concentration. BH4- tends to form contact ion pairs with Na+ at the Na-B distances of 3.24 angstrom and 2.82 angstrom in tetrahedral-corner-shared and tetrahedral-edge-shared fashions, respectively; the number of Na-B interactions increases from 0.3 +/- 0.5 in 1.0 mol.dm(-3) (almost negligible) to 2.1 +/- 0.9 in 9.0 mol.dm(-3). Tetrahedral-edge-shared bidentate ion pair is likely to be the preferred and dominant ion cluster over the wide concentration range. Ion association between the Na+ and BH4- was crosschecked by density function theory (DFT) calculations on [NaBH4(H2O)(6)] clusters. (C) 2018 Elsevier B.V. All rights reserved.
DOI	10.1016/j.molliq.2018.10.124
引用统计
文献类型	期刊论文
条目标识符	http://ir.isl.ac.cn/handle/363002/34086
专题	盐湖资源与化学实验室中国科学院青海盐湖研究所
推荐引用方式 GB/T 7714	Zhou, Yongquan,Yamaguchi, Toshio,Yoshida, Koji,et al. Structure of alkaline aqueous NaBH4 solutions by X-ray scattering and empirical potential structure refinement[J]. JOURNAL OF MOLECULAR LIQUIDS,2019,274:173-182.
APA	Zhou, Yongquan,Yamaguchi, Toshio,Yoshida, Koji,Fang, Chunhui,Fang, Yan,&Zhu, Fayan.(2019).Structure of alkaline aqueous NaBH4 solutions by X-ray scattering and empirical potential structure refinement.JOURNAL OF MOLECULAR LIQUIDS,274,173-182.
MLA	Zhou, Yongquan,et al."Structure of alkaline aqueous NaBH4 solutions by X-ray scattering and empirical potential structure refinement".JOURNAL OF MOLECULAR LIQUIDS 274(2019):173-182.

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