Bromination of 2D materials

• Published in: Nanotechnology 2024-04, Vol.35 (14), p.145703
• Main Authors: Freiberger, Eva Marie, Steffen, Julien, Waleska-Wellnhofer, Natalie J, Hemauer, Felix, Schwaab, Valentin, Görling, Andreas, Steinrück, Hans-Peter, Papp, Christian
• Format: Article
• Language: English
• Subjects: bromine; functionalization; graphene; hexagonal boron nitride; machine-learning force field; molecular dynamics; x-ray photoelectron spectroscopy
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/1361-6528/ad1201

The adsorption, reaction and thermal stability of bromine on Rh(111)-supported hexagonal boron nitride ( -BN) and graphene were investigated. Synchrotron radiation-based high-resolution x-ray photoelectron spectroscopy (XPS) and temperature-programmed XPS allowed us to follow the adsorption process and the thermal evolution on the molecular scale. On -BN/Rh(111), bromine adsorbs exclusively in the pores of the nanomesh while we observe no such selectivity for graphene/Rh(111). Upon heating, bromine undergoes an on-surface reaction on -BN to form polybromides (170-240 K), which subsequently decompose to bromide (240-640 K). The high thermal stability of Br/ -BN/Rh(111) suggests strong/covalent bonding. Bromine on graphene/Rh(111), on the other hand, reveals no distinct reactivity except for intercalation of small amounts of bromine underneath the 2D layer at high temperatures. In both cases, adsorption is reversible upon heating. Our experiments are supported by a comprehensive theoretical study. DFT calculations were used to describe the nature of the -BN nanomesh and the graphene moiré in detail and to study the adsorption energetics and substrate interaction of bromine. In addition, the adsorption of bromine on -BN/Rh(111) was simulated by molecular dynamics using a machine-learning force field.