Hydrogenating borophene
The two-dimensional material borophene, which is formed on silver surfaces, has a diverse polymorphism and is expected to have unusual materials and electronic properties. However, it is very unstable outside ultra-high vacuum conditions and oxidizes readily, making research into its properties difficult. Li et al. hydrogenated these materials with atomic hydrogen and showed that borophane has a lower local work function. This material is stable in the air for days and borophene can be easily recovered by thermally expelling the hydrogen.
Science, this issue p. 1143
Abstract
Synthetic two-dimensional polymorphs of boron, or borophene, have attracted attention for their anisotropic metallicity, correlated electron phenomena, and diverse superlattice structures. Although heterostructures of borophene have been realized, ordered chemical modification of borophene has not yet been reported. Here we synthesize “borophane” polymorphs by hydrogenating borophene with atomic hydrogen in ultra-high vacuum. By means of atomic scale imaging, spectroscopy and calculations based on the first principles, it is shown that the most common borophane polymorph has a combination of two center two electron boron hydrogen and three center two electron boron hydrogen. -drill bonds. . Borophane polymorphs are metallic with modified local work functions and can be reversibly recycled to pristine borophene by thermal desorption of hydrogen. Hydrogenation also provides chemical passivation because borophane decreases oxidation rates by more than two orders of magnitude after exposure to the environment.