Preparation and characterization of single/few layer antimonene and germanium

• Applicant: Professor Dr. Andreas Hirsch, since 12/2018
• Subject Area: Solid State and Surface Chemistry, Material Synthesis ; Experimental Condensed Matter Physics ; Organic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 397380167

• Final Report Year: 2022

Final Report Abstract

Two-dimensional (2D) materials (from one up to few atomic layers in thickness) present a huge potential for technological applications. Over the past 12 years we have witnessed 3 major activity waves in this area: Graphene, 2D transition-metal dichalcogenides, and phosphorene. We anticipate the next waves to be related to two elemental materials: Antimony and Germanium. Consequently, the main goal of 2D-Sb&Ge is to provide the research community with the understanding of the properties and the basics to fabricate and make use of novel 2D materials based on these two elements. This also includes the study of their physical and chemical properties including supramolecular and/or covalent functionalization to produce a series of band gap tuneable devices. Graphene is a semimetal with zero gap which precludes it for many applications in (opto)electronics. A number of theoretical works predicted antimony as a promising material for optoelectronic applications due to the band gap opening when thinned down to one atomic layer. In addition, it has also been predicted to exhibit topological character and conducting surface states in its few-layer form. Members of this consortium have demonstrated, for the first time that antimony can be exfoliated by micromechanical and liquid phase techniques and have characterized the resulting 2D flakes from a structural morphological point of view. In particular, we have shown that unlike black phosphorus, single layers of antimonene are stable in atmospheric conditions. Electrical characterization and theoretical work in this regard are currently under way. Furthermore, we have been now able to provide a continuous flow method for the preparation of high quality antimonene hexagons. The second 2D material, recently produced in our labs and which also features very promising optoelectronic properties, is a 2D form of alpha-germanium (2D-α-Ge), not to be mistaken with germanene, the hexagonal form that only grows on metallic surfaces. Theoretical calculations carried out from a member of this consortium predict exciting electrical properties such as band gap tuning as a function of the thickness. The 2D-Sb&Ge project has been structured in three different interconnected lines: i) Materials production including their chemical functionalization and structural/morphological characterization. ii) Experimental studies of their physical properties. iii) Theoretical modelling for design and rationalization of experimental results. We have evaluated the experimental conditions to produce few-layer (FL) germanium and antimonene at a large scale. We have explored the electronic features of antimonene and the remarkable surface properties of this novel material. Finally, we have discovered that 2D nanosheets of Sb, exfoliated in the IL bmim-BF4, catalyse the alkylation of soft nucleophiles with alkyl esters, in good yields and selectivity, particularly for aromatic substrates. All these results have been supported by theoretical calculations to rationalize their physical and chemical properties and will aid in future materials design. These new results foresee applications in the context of energy (supercapacitor, water splitting, oxygen reduction, etc.) as well as in prototypes of optoelectronic devices.

Publications

• Recent Progress on Antimonene: A New Bidimensional Material. Adv. Mater. 30, Art. Num. 1703771 (2018)
  P. Ares, J.J. Palacios, G. Abellan, J. Gomez-Herrero, F. Zamora
  
• (2019) Liquid phase exfoliation of antimonene: systematic optimization, characterization and electrocatalytic properties J. Mater. Chem. A, 2019, J. Mater Chem. A 7, 22475-22486
  Gibaja, C., Asseban, M., Torres, I., Fickert, M., Sanchis-Gual, R., Brotons, I., Paz, W. S., Palacios, J. J., Michel, E. G., Abellán, G., Zamora, F.
  
• (2020) Unveiling the oxidation behavior of liquid-phase exfoliated antimony nanosheets, 2D Materials, 2020, 7 (2), 25039
  Assebban, M.; Gibaja, C.; Fickert, M.; Torres, I.; Weinreich, E.; Wolff, S.; Gillen, R.; Maultzsch, J.; Varela, M.; Rong, S. T. J.; Loh, K. P.; Michel, E. G.; Zamora, F.; Abellán, G.
  
• Unveiling the oxidation behavior of liquid-phase exfoliated few-layer antimonene. 2D Materials 7, Art Num 025039 (2020)
  Mhamed Assebban, Carlos Gibaja, Michael Fickert, Iñigo Torres, Erik Weinreich, Stefan Wolff, Roland Gillen, Janina Maultzsch, Maria Varela, Sherman Tan Jun Rong, Kian Ping Loh, Enrique García Michel, Félix Zamora, Gonzalo Abellán
  
• Continuous-Flow Synthesis of High-Quality Few-Layer Antimonene Hexagons, Adv. Funct. Mater. 2021, 31 (28), 2101616
  Torres, I., Alcaraz, M., Sanchis-Gual, R., Carrasco, J.A., Fickert, M., Assebban, M., Gibaja, C., Dolle, C., Aldave, D.A., Gómez-Navarro, C., Salagre, E., García Michel, E., Varela, M., Gómez-Herrero, J., Abellán, G., Zamora, F.
  
• Exfoliation of Alpha-Germanium: A Covalent Diamond-Like Structure, Adv. Mater. 2021, 33 (10), 2006826
  Gibaja, C., Rodríguez-San-Miguel, D., Paz, W. S., Torres, I., Salagre, E., Segovia, P., Michel, E. G., Assebban, M., Ares, P., Hernández- Maldonado, D., Ramasse, Q., Abellán, G., Gómez-Herrero, J., Varela, M., Palacios, J. J., Zamora, F.