DFT Study of Planar Boron Sheets: A New Template for Hydrogen Storage

We study the hydrogen storage properties o f p lanar boron sheets and com pare them to those o f graphene. T he b inding o f m olecular hydrogen to the boron sheet (0.05 eV ) is stronger than that to graphene. W e find that d ispersion o f alkali m etal (A M = Li, Na, and K) atom s onto the boron sheet m arkedly increases hydrogen binding energies and storage capacities. The unique structure o f the boron sheet presents a tem plate for creating a stable lattice o f strongly bonded m etal atom s w ith a large nearest neighbor distance. In contrast, A M atom s dispersed on graphene tend to cluster to form a bulk m etal. In particu lar the boron-L i system is found to be a good candidate for hydrogen storage purposes. In the fu lly loaded case this com pound can contain up to 10.7 w t % m olecular hydrogen w ith an average b inding energy o f 0.15 eV /H 2. ^Computational Materials Science, Faculty of Science and Technology and MESA+ Research Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands ^Electronic Structure of Materials, Institute for Molecules and Materials, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.