Introducing borophane, a chemically stable form of borophene

By modifying borophene with hydrogen, researchers have converted the atomically thin, unstable 2D form of boron to a chemically stable form dubbed borophane. The work makes the ultrathin form of boron more robust and easier to handle, opening the door to applications (Science 2021, DOI: 10.1126/science.abg1874). As various types of 2D materials started to stack up about 10 years ago, researchers wondered whether they could wrangle boron, an inherently 3D material, into a 2D form. Theoretical studies suggested that borophene would be mechanically strong and flexible and have electronic properties that could be useful in fast electronics and energy storage devices. In 2015, two teams succeeded in preparing borophene samples by growing 2D films in chemically controlled environments. The problem, according to Northwestern University’s Mark C. Hersam, a member of one of those teams, is that borophene oxidizes immediately upon exposure to air, making it nonconductive and ruining other potentially useful properties. Hersam and coworkers now report that treating borophene with atomic hydrogen in vacuum renders the material stable in air for about 1 week. The team found that the hydrogenation step is reversible, suggesting it could be used to protect the material during ambient processing, then undone to restore pristine borophene after the film has been encased in an electronic device.