Synthesis and characterization of novel anionic transition metal borohydrides

Abstract

Zinc borohydride (Zn(BH4)2) has been the focus of much recent research in the field of hydrogen storage. This material has a low decomposition temperature (around 85°C) and a high theoretical hydrogen capacity (8.5% H2). These studies include mechanochemical synthesis of zinc borohydride and its derivatives at room temperature without solvent following the reaction: ZnX2 + nMBH4-> Mn-2Zn(BH4)n + 2MX where M = Li, No, or K; X = Cl; and n = 1, 2, 3, or 4. Product mixtures were characterized by IR, XRD, and CPMAS B NMR spectroscopy. Analysis of material properties was completed by thermal decomposition mass spectrometry (TD-MS) and isothermal dehydrogenation studies. These fundamental studies confirmed the synthesis of novel borohydride materials. It was found that the milling of zinc chloride with a1ka1i borohydrides reduces the dehydrogenation temperature. However, upon dehydrogenation, both hydrogen and diborane are liberated.