Tuning the work functions via topology and halogen element adsorbates: A first-principles investigation on MBene nanoribbons

One-dimensional nanoribbons have foreshadowed potential applications in nanoelectronics due to their fascinating quantum confinement effects. We present theoretical assessment from first-principles calculations to explore the work functions of Ti2B-based MBene nanoribbons, focusing on the size, edge, and functionalization dependencies. We found that the bare and halogen-functionalized Ti2B nanoribbons exhibit metallic properties and chemical stability. The work function of both bare and halogen-terminated armchair Ti2B nanoribbons tends to saturate as width. In contrast, the work function of zigzag Ti2B nanoribbons varies complexly with width and has been discussed in terms of the non-equivalent edges and halogen termination. The work functions of halogen-terminated Ti2B nanoribbons have been found to be significantly affected by the edge dipole moments, which are determined by three factors: functionalization-induced electron redistribution at the edge, the electronegativity of halogen functional groups, and the edge reconstruction. These findings provide valuable insights for designing, characterizing, and utilizing the proposed nanostructures.