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Metal structures with an ultimate thickness of one atomic layer (metallenes) have attracted increasing research interest due to their low dimensionality and unique properties, including ultrahigh carrier mobility and enhanced catalytic activity, making them promising candidates for electrocatalysis, sensing, and next-generation electronics [1].
However, realizing metallenes is hindered by strong metallic bonding, which favors the formation of three-dimensional clusters rather than two-dimensional structures [2]. To overcome this limitation, we plan to use ultra-low-energy (tens to hundreds of eV) ion irradiation to first introduce vacancies into graphene and then place metal atoms on the graphene surface. Vacancies serve as trapping sites for metal atoms and as strain-inducing sites, enabling the formation of new, energetically favorable phases. A similar approach has been used to create 2D gold structures on [3,4].
For reliable characterization of metallenes, it is crucial to avoid surface contamination during and after implantation. One way to obtain a clean graphene surface is to anneal it under vacuum at high temperatures [5]. However, breaking the vacuum leads to contamination buildup on the surface. The University of Uppsala's time-of-flight medium-energy ion scattering (ToF-MEIS) system offers a promising approach by connecting a MEIS chamber, used for metal implantation and quantitative sputter/recoil analysis [6], to a vacuum annealing vessel, ensuring the sample is never exposed to pressures above $\sim$ 10$^{-8}$ mbar [7]. However, as the current MEIS system only allows irradiation at energies from a few to hundreds of keV, we plan to extend the MEIS setup with a deceleration unit to bring ions into the ultra-low-energy regime. This will enable in situ cleaning, metal implantation, and ion-beam analysis of the resulting structures, allowing us to experimentally study metallenes on a new scale.
[1] Fengzhu Ren et al. 2026 Adv. Mater. 38 12683
[2] Kameyab Raza Adibi et al. 2024 Nanoscale 16 19649
[3] Wael Joudi et al. 2025 ACS Nano 19 22032
[4] Alberto Trentino et al. 2022 2D Mater. 9 025011
[5] Philipp Irschik et al. 2026 2D Mater. 13 025001
[6] Radek Holeňák et al. 2025 Vacuum 204 111343
[7] Radek Holeňák et al. 2025 Vacuum 231 113824