Nb ₂ CBr ₂ MXene Monolayer as a Novel Material: A First Principle Study

Abstract Niobium‐based MXenes show promising properties and applications, but have not yet been sufficiently investigated, especially with halogen surface terminations. This study investigates the structural, electronic, optical, vibrational, and thermodynamic properties of the unique trigonal (Nb‐MXene) monolayer using the density functional theory (DFT) formalism with the GGA‐PBE functional. The results of the lattice parameters and bond lengths are compared with the theoretical and experimental data for similar structures. The monolayer exhibits structural stability, since the phonon dispersion results do not reveal negative frequencies, with a cohesive energy of 4.36 eV per atom, and a negative formation energy of –3.85 eV, confirming thermodynamic stability. The band structure indicates that Nb‐MXene is a metal with potential applications as a supercapacitor, as well as revealing potential superconductor characteristics. The optical absorption properties reveal that Nb‐MXene is sensitive to the plane of polarization of incident light, absorbs in the visible region (400–700 nm), and has potential applications as a UVC (100–280 nm) optical filter and as an optical fiber sensor. Thermodynamic properties as a function of temperature are calculated up to 1000 K to characterize the stability of Nb‐MXene. Infrared (IR) and Raman spectra are calculated and assigned, serving as a useful theoretical reference for experimental monolayer characterization. The findings suggest that Nb‐MXene is a promising candidate for photonic and biomedical applications.