On the hydrogen storage performance of Cu-doped and Cu-decorated graphene quantum dots: a computational study
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On the hydrogen storage performance of Cu‑doped and Cu‑decorated graphene quantum dots: a computational study Michal Malček1 · Lukáš Bučinský1 Received: 4 March 2020 / Accepted: 5 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Hydrogen gas is a promising renewable energy source. The hydrogen storage performance of two differently modified graphene surfaces, particularly Cu-doped and Cu-decorated circumcoronene (CC), is investigated using density functional theory, 6-311G* basis set and Bader’s quantum theory of atoms in molecules (QTAIM). It is found that the Cu-doped CC is able to bind three H2 molecules on one Cu atom, while the Cu-decorated CC is able to bind up to five H2 molecules on one Cu atom. Changes in the topology of charge density upon the H 2 adsorption are evaluated under the formalism of QTAIM analysis. The QTAIM analysis of bond critical points as well as the density of states analysis show that the interaction between Cu and adsorbed H 2 molecules can be considered as a physisorption (a van der Waals type interaction). Overall, the results presented in this study point out that the Cu-decorated graphene surfaces are more suitable potential candidates for hydrogen storage than the Cu-doped ones. Furthermore, the inclusion of diffuse functions in the basis set is critically considered. Keywords Circumcoronene · DFT · Graphene quantum dots · Electronic structure · Hydrogen storage · QTAIM analysis
1 Introduction In the last two decades, graphene based materials have attracted a huge attention due to their extraordinary chemical, mechanical, electronic and optical properties [1–7]. Graphene, rediscovered and isolated in 2004 [1], is a two dimensional monolayer of s p2-hybridized carbon atoms arranged in a hexagonal honeycomb lattice. In 2007, Schedin et al. [3] have proposed an idea to use graphene materials as adsorbents of individual gas molecules. However, the pristine graphene behaves like a zero-band-gap semiconductor, due to the overlap of its valence and conduction bands at the Brillouin zone [8]. Published as part of the topical collection of articles from the 17th edition of the Central European Symposium on Theoretical Chemistry (CESTC 2019) in Austria Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00214-020-02680-2) contains supplementary material, which is available to authorized users. * Michal Malček [email protected] 1
Faculty of Chemical and Food Technology, Institute of Physical Chemistry and Chemical Physics, Slovak University of Technology in Bratislava, Radlinského 9, 812 37 Bratislava, Slovak Republic
Opening of this band gap is highly desirable because it significantly enhances the electronic properties and chemical reactivity of graphene materials [8]. Opening of this bang gap can be performed either by doping (i.e. replacing a carbon atom with the dopant atom) or by decorating (i.e. placing a heteroatom above the carbon layer) of the graphene surfaces (
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