Structural Prediction Of B₃₂ And Hydrogen Storage On Metal Decorated Planar Boron Sheets

In recent years, with carbon nanostructures including carbon nanotubes, carbonfullerenes, and graphenes having been deeply investigated, the boron nanostructureshave widely attracted attention. Boron element has the characters of lightweight andelectrons deficiency. Its nanostructures include small size boron clusters, boronnanotubes, boron fullerenes and graphene-like boron sheets. In this dissertation, basedon density functional theory, we calculations the lowest-lying configurations of B₃₂2clusters and investigate the properties of hydrogen storage on metal decorated planarboron sheet. The results are as follows:（1） Among the B₃₂clusters which we have widely searched, a staggereddouble-ring tubule has been confirmed as a strong candidate for the global minimum.Four new metastable B₃₂structures have also been observed, and in addition, weidentify a novel stable B₃₂rugby-like tubular structure that may be an embryo that canbe extended into nanotubes. A series of thin boron nanotubes are derived based onthis isomer.（2） We calculation the properties of hydrogen storage on alkaline-earth metals（Be, Mg, and Ca） coated2×2-boron sheet, making Ca to be the most attractivedecorating element among all the alkaline-earth elements. The charge transfer fromCa to-boron sheet. The results shows that with2Ca atoms decorated on the bothsides of-boron sheet, each Ca can store up to4H2molecules, the average bindingenergy can reach⁰.133eV and the maximal hydrogen storage capacity is8.77wt.%.The enhance binding energy of H2molecules on the Ca decorated-boron sheet canattributed to the electrostatic interactions and orbital hybridizations between Ca-3dorbital and H-s orbital.（3） The physisorption of H2molecules on a pristine2×2Z（1/12） boron sheetgives a binding energy of⁰.103eV/H2. We further address that Li atoms coatedZ（1/12） boron sheet can bind up to4H2molecules each Li with an average binding energy of0.247eV, leading to a hydrogen storage capacity of10.8wt.%. Through thedifference charge density analysis we find that the polarization mechanism and orbitalhybridizations act on the adsorbed H2molecules. We predict that Li atoms coatedZ（1/12） boron sheet can serve as a high-capacity hydrogen storage medium.