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Hydrogenate borophene
Borophene, a two-dimensional material formed on silver surfaces, exhibits diverse polymorphism and is expected to have unusual materials and electronic properties. However, it is very unstable outside of ultra-vacuum conditions and oxidizes easily, which hinders the exploration of its properties. Li et al. hydrogenated these materials with atomic hydrogen and showed that borophane has an inferior local working function. This material is stable for days in air and the borophene can be recovered simply by thermally removing the hydrogen.
Science, this issue p. 1143
Abstract
The two-dimensional synthetic polymorphs of boron, or borophene, have gained attention due to their anisotropic metallicity, correlated electron phenomena, and various superlattice structures. Although borophene heterostructures have been performed, an orderly chemical modification of borophene has not yet been reported. Here, we synthesize “borophane” polymorphs by hydrogenating borophene with atomic hydrogen under ultra-vacuum. Through atomic-scale imaging, spectroscopy, and first-principle calculations, the most common borophane polymorph possesses a combination of two-center-two-electron and three-center-two-electron boron-hydrogen bonds. hydrogen-boron. Borophane polymorphs are metallic with altered local working functions and can be reversibly returned to virgin borophene by thermal desorption of hydrogen. Hydrogenation also provides chemical passivation, as borophane reduces oxidation rates by more than two orders of magnitude after ambient exposure.
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