Ti4- and Ni4-Doped Defective Graphene Nanoplatelets as Efficient Materials for Hydrogen Storage

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• 作者：C. M. Ramos-Castillo ; J. U. Reveles ; M. E. Cifuentes-Quintal ; R. R. Zope ; R. de Coss
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：March 10, 2016
• 年：2016
• 卷：120
• 期：9
• 页码：5001-5009
• 全文大小：466K
• ISSN：1932-7455

文摘

We report a detailed theoretical investigation of the structural and electronic properties of titanium- and nickel-doped defective graphene nanoplatelets, which are shown to be efficient materials for hydrogen storage. We found that Hb>2b> bond cleavage is favored by Tib>4b>-doped defective graphene nanoplatelets because of the strong interaction between the hydrogen 1s and titanium 3d levels that leads to the formation of metal hydrides, while Hb>2b> adsorption on Nib>4b>-doped defective graphene favors the formation of Kubas complexes as hydrogen 1s levels only interact with the nickel 4s levels. A comparison between adsorption energies, number of Hb>2b> adsorbed molecules, and hydrogen gravimetric content shows that Tib>4b>-doped graphene has a better performance for hydrogen storage with a notably high hydrogen gravimetric content of 3.4 wt %; than Nib>4b>-doped graphene with a 10-fold lower gravimetric content of only 0.30 wt %. This observation can be explained by three factors: Ti is a lighter transition metal, it absorbs a larger amount Hb>2b> per metallic atom, and it presents a planar geometry that increases the coverage of the graphene layer and makes possible that all atoms in the cluster participate in the Hb>2b> adsorption. Our results support the hypothesis that a controlled introduction of defects in graphene followed by the anchoring of small metallic clusters is a feasible way to enhance the hydrogen gravimetric content of graphene nanoplatelets and to fine-tune hydrogen absorption energies to achieve a reversible operation at ambient temperature and moderates pressures, addressing one of the main challenges of a sustainable hydrogen-based economy.