Delacroix Simon, Le Godec Yann, Coelho-Diogo Cristina, Gervais Christel, Génois Isabelle, Le Griel Patrick, Portehault David
Sorbonne Université, CNRS, Collège de France, Laboratoire de Chimie de la Matière Condensée de Paris (CMCP), 4 place Jussieu, F-75005 Paris, France.
Sorbonne Université, CNRS, MNHN, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), 4 place Jussieu, F-75005 Paris, France.
Inorg Chem. 2020 Oct 19;59(20):14983-14988. doi: 10.1021/acs.inorgchem.0c01694. Epub 2020 Oct 1.
Lithium borides have been synthesized exclusively through classical solid-state chemistry processes that lead to bulk materials. Indeed, due to the lack of reactivity of the solid boron precursors usually employed and to the high covalent connectivity in such solids, high temperatures and long reaction times are necessary to obtain lithium borides. These conditions result in extensive crystal growth. Here we present the synthesis of nanoparticles of a lithium boride bearing tunnel-like cavities templated by neutral LiO species, which have been reported to be labile. To reach this goal, a liquid-phase synthesis in inorganic molten salts has been developed. The LiB(LiO) nanoparticles have been characterized by scanning and transmission electronic microscopy (SEM and TEM), X-ray diffraction (XRD), and Raman spectroscopy. We provide an in-depth structural characterization by using H, Li, and B solid-state nuclear magnetic resonance (NMR) coupled with DFT modeling to provide the first assignment of Li and B solid-state NMR signals in lithium borides. We then assess the nanoparticle morphology oriented along the direction of the cavities. This feature shows similarities with structurally related hexagonal tungsten bronzes and could therefore affect the electrochemical and ion exchange properties.
硼化锂一直以来都是通过传统的固态化学过程合成的，这些过程会生成块状材料。实际上，由于通常使用的固态硼前驱体缺乏反应活性，以及此类固体中存在高共价连接性，因此需要高温和长时间反应才能得到硼化锂。这些条件导致晶体大量生长。在此，我们展示了一种由中性LiO物种模板化的、带有隧道状空腔的硼化锂纳米颗粒的合成方法，据报道这些LiO物种不稳定。为了实现这一目标，我们开发了一种在无机熔盐中的液相合成方法。通过扫描电子显微镜和透射电子显微镜（SEM和TEM）、X射线衍射（XRD）以及拉曼光谱对LiB(LiO)纳米颗粒进行了表征。我们使用H、Li和B固态核磁共振（NMR）并结合DFT建模进行了深入的结构表征，以首次确定硼化锂中Li和B固态NMR信号。然后，我们评估了沿空腔方向取向的纳米颗粒形态。这一特征与结构相关的六方钨青铜相似，因此可能会影响其电化学和离子交换性能。
