Prediction of single-layer antimony oxyselenide (Sb₂O₂Se₂): metal-to-semiconductor transition via hydrogenation

In this study, the structural, electronic, vibrational, and mechanical properties of single-layer Antimony Oxyselenide (Sb₂O₂Se₂) and its hydrogenated structure (Sb₂O₂Se₂H₂) are investigated by performing density functional theory-based first principles calculations. Geometry optimizations reveal that single-layer Sb₂O₂Se₂crystallizes in tetragonal structure which is shown to possess dynamical stability by means of phonon band dispersions. In addition, the mechanical stability of the predicted single layer is satisfied via the linear-elastic parameters. Electronically, it is revealed that single-layer Sb₂O₂Se₂exhibits metallic behavior whose highest occupied states are found to arise from the surface Se atoms, may be an indication for tuning the electronic features via surface functionalization. For the surface modification of Sb₂O₂Se₂, top of each Se atom is saturated with a H atom and fully hydrogenated single-layer Sb₂O₂Se₂H₂is shown to be an in-plane anisotropic structure. Phonon band dispersion calculations indicate the dynamical stability of Sb₂O₂Se₂H₂. Mechanically stable Sb₂O₂Se₂H₂is found to possess anisotropic linear-elastic behavior, which is much softer than its pristine structure. Moreover, electronically a metallic-to-semiconducting transition is shown to occur as the unoccupied Se-orbitals are saturated via H atoms. Our work offers insights into prediction of a novel single-layer material, namely Sb₂O₂Se₂, and reports the chemically-driven semiconducting behavior via hydrogenation, which may lead to the use of hydrogenated structure in solar cell, photoelectrode, or photocatalyst applications owing to its suitable band gap.