STM 12

Hydrogen absorption in three-dimensional graphene structures epitaxially grown on 4H SiC(0001)

Hydrogen is one of the most promising compounds that can be used as an energy vector, allowing the chemical storage of energy produced via renewable sources. Reliable hydrogen storage is one of the fundamental milestones that must be met to allow for the widespread use of the molecule as energy vector. Graphene offers some advantageous proprieties that makes it an interesting substrate for solid state hydrogen storage devices. However, flat pristine graphene cannot be used for this application, since a device would require an unreasonably large surface to adsorb a useful amount of hydrogen.

A porousified 4H SiC(0001) wafer can be used as the starting material for a process of epitaxial graphene growth in which the thermal annealing of the crystal favors the sublimation of Si compounds, resulting in the accumulation of C on the crystal face. Superficial carbon atoms can then reconstruct and form a layer of graphene which follows the complex morphology of the etched wafer. The result is a three-dimensional graphene structure that compresses a large graphene surface in a small volume.

Deuterium absorption in this three-dimensional graphene is studied via Thermal Desorption Spectroscopy (TDS), exposing the samples to either atomic (D) or molecular (D2) deuterium. The graphene growth temperature and the hydrogen exposure temperature influence the amount of deuterium that can bind to the substrate. We find that the three-dimensional graphene structures form covalent bonds to atomic deuterium, because distinct chemisorption peaks are observed after exposing the samples to D, see Fig. 1. Signals at similar position are also observed when the sample is exposed to D2. The observation of such signals after exposing the sample to D2 is particularly interesting since this is the first report of such an event in unfunctionalized graphene-based materials and implies the presence of a catalytic splitting mechanism taking place on the structure surface. The TDS spectra shown in Fig. 1 also demonstrate that chemisorption takes place in at least two different sites, resulting in different binding energies for the two interactions. Our data further show that the three-dimensional dendritic structure of the porous material temporarily retains the deuterium molecules after their desorption and causes their delayed emission from the substrate.


Figure 1: TDS spectra of a three-dimensional graphene sample after hydrogenation using atomic (D) or molecular (D2) deuterium. A TDS spectrum of pristine porous SiC (before graphene growth) is also reported. Inset: Individual plot of the TDS D2 spectrum reported in the main figure.

Publications:

  1. Stefano Veronesi, Georg Pfusterschmied, Filippo Fabbri, Markus Leitgeb, Omer Arif, Daniel Esteban Arenas, Sara Bals, Ulrich Schmid, Stefan Heun: 3D arrangement of epitaxial graphene conformally grown on porousified crystalline SiC, arXiv:2112.11319 [cond-mat.mtrl-sci].
  2. S. Veronesi, G. Pfusterschmied, F. Fabbri, M. Leitgeb, O. Arif, D. A. Esteban, S. Bals, U. Schmidt, S. Heun: 3D arrangement of epitaxial graphene conformally grown on porousified crystalline SiC, Carbon 189 (2022) 210 – 218.
  3. Aureliano Macili: Hydrogen storage in three-dimensional arrangement of epitaxial graphene conformally grown on porousified SiC, Master Thesis, University of Pisa, Italy, 2022.
  4. Macili, Aureliano and Pfusterschmied, Georg and Leitgeb, Markus and Schmid, Ulrich and Heun, Stefan and Veronesi, Stefano: Hydrogen Storage in a Novel Three-Dimensional Graphene Structure. Available at SSRN.
  5. Aureliano Macili, Ylea Vlamidis, Georg Pfusterschmied, Markus Leitgeb, Ulrich Schmid, Stefan Heun, Stefano Veronesi: Study of hydrogen absorption in a novel three-dimensional graphene structure: Towards hydrogen storage applications, arXiv:2302.08813 [cond-mat.mtrl-sci].
  6. Aureliano Macili, Ylea Vlamidis, Georg Pfusterschmied, Markus Leitgeb, Ulrich Schmid, Stefan Heun, Stefano Veronesi: Study of hydrogen absorption in a novel three-dimensional graphene structure: Towards hydrogen storage applications, Applied Surface Science 615 (2023) 156375. [Link]

Presented at:

  1. Aureliano Macili: Hydrogen storage in three-dimensional arrangement of epitaxial graphene conformally grown on porousified SiC, Master thesis defense, University of Pisa, Italy, 03 June 2022. [Talk]
  2. S. Heun: Hydrogen Storage in Graphene, Karl-Franzens-Universität Graz, Austria (Dr. Donato Civita/Prof. Leonhard Grill), 17 March 2023. [Abstract] [Talk]
  3. S. Heun: Prospects for Hydrogen Storage in Graphene, Montanuniversität Leoben, Austria (Prof. Christian Teichert), 20 March 2023. [Abstract] [Talk]
  4. Stefano Veronesi, Aureliano Macili, Ylea Vlamidis, Emanuele Pompei, Georg Pfusterschmied, Markus Leitgeb, Ulrich Schmid, Stefan Heun: Hydrogen absorption in a novel three-dimensional graphene structure: Towards hydrogen storage applications, CMD 30 Fismat 2023, Milan, Italy, September 4 – 8, 2023. [Abstract] [Talk]
  5. Stefan Heun: Prospects for Hydrogen Storage in Graphene, Kwansei Gakuin University, Sanda, Hyogo, Japan (Prof. H. Hibino), 2 October 2023. [Abstract] [Talk]