Grinderslev, Jakob B. Jepsen, Lars H. Lee, Young-Su Moller, Kasper T. Cho, Young Whan Cerny, Radovan Jensen, Torben R. 2024-01-19T16:33:37Z 2024-01-19T16:33:37Z 2021-09-02 2020-09-08 0020-1669 https://pubs.kist.re.kr/handle/201004/118130 Metal borohydrides are a fascinating and continuously expanding class of materials, showing promising applications within many different fields of research. This study presents 17 derivatives of the hydrogen-rich ammonium borohydride, NH4BH4, which all exhibit high gravimetric hydrogen densities (>9.2 wt % of H-2). A detailed insight into the crystal structures combining X-ray diffraction and density functional theory calculations exposes an intriguing structural variety ranging from three-dimensional (3D) frameworks, 2D-layered, and 1D-chainlike structures to structures built from isolated complex anions, in all cases containing NH4+ countercations. Dihydrogen interactions between complex NH4+ and BH4- ions contribute to the structural diversity and flexibility, while inducing an inherent instability facilitating hydrogen release. The thermal stability of the ammonium metal borohydrides, as a function of a range of structural properties, is analyzed in detail. The Pauling electronegativity of the metal, the structural dimensionality, the dihydrogen bond length, the relative amount of NH4+ to BH4-, and the nearest coordination sphere of NH4+ are among the most important factors. Hydrogen release usually occurs in three steps, involving new intermediate compounds, observed as crystalline, polymeric, and amorphous materials. This research provides new opportunities for the design and tailoring of novel functional materials with interesting properties. English AMER CHEMICAL SOC EFFECTIVE IONIC-RADII THERMAL-DECOMPOSITION LITHIUM BOROHYDRIDE CRYSTAL-STRUCTURE STORAGE CHEMISTRY HYDRIDES SERIES LI CONDUCTIVITY Structural Diversity and Trends in Properties of an Array of Hydrogen-Rich Ammonium Metal Borohydrides Article 10.1021/acs.inorgchem.0c01797 1 INORGANIC CHEMISTRY, v.59, no.17, pp.12733 - 12747 INORGANIC CHEMISTRY 59 17 12733 12747 scie scopus 000570979900092 2-s2.0-85090487970 Chemistry, Inorganic & Nuclear Chemistry Article EFFECTIVE IONIC-RADII THERMAL-DECOMPOSITION LITHIUM BOROHYDRIDE CRYSTAL-STRUCTURE STORAGE CHEMISTRY HYDRIDES SERIES LI CONDUCTIVITY