Semiconducting Borophene Realized via Hydrogenation-Driven Structural Reconstruction

Hydrogenation provides a robust approach to both dramatically improve borophene's ambient stability and induce semiconducting behavior-two essential requirements for its integration into nanoelectronic and optoelectronic devices. However, the vast configurational diversity of hydrogen adsorption patterns impedes the identification of a definitive semiconducting hydrogenated borophene phase. In this work, we conducted systematic high-throughput searches to investigate various hydrogen coverages on α'-borophene and determined that semi-hydrogenated configurations constitute the most promising semiconducting candidates. Guided by these predictions, we synthesized semi-hydrogenated borophene, α'-B₈H₄ via chemical vapor deposition. Subsequent extensive structural characterization and complementary computational simulations provided compelling evidence for the formation of this stable semiconducting phase. In sharp contrast to the previously proposed α'-4H model, the synthesized α'-B₈H₄ undergoes hydrogenation-induced structural reconstruction-stabilized by both two-center-two-electron B-H and three-center-two-electron B─H─B bonds-whose ensuing out-of-plane buckling drives strong hybridization between in-plane and out-of-plane p orbitals, thereby opening a band gap. This combined theoretical and experimental study identifies an air-stable semiconducting borophene and paves the way for borophenes as next-generation electronic and optoelectronic materials.