Investigations of two-dimensional Zirconium carbide/nitride MXenes in the presence of Oxygen/Fluorine functional groups

MXenes, a promising class of two-dimensional (2D) transition metal (TM) carbides/nitrides, have demonstrated considerable potential in a variety of cutting-edge technological applications. In this study, the effect of oxygen/fluorine termination groups on the electronic and optical properties of 2D zirconium carbide/nitride [Zr2XT2 (X = C, N; T = O, F)] MXenes is thoroughly investigated. We utilized a "density functional theory (DFT) based full-potential linearized augmented plane wave (FP-LAPW)" approach to analyze the band structures of Zr2XT2. The results revealed notable variations in the electronic structures as the X elements and the terminating groups were modified. Zr2CO2 demonstrated semiconducting behavior and exhibited a band gap of 0.60 eV, while Zr2CF2, Zr2NO2, and Zr2NF2 demonstrated metallic properties. Moreover, we examined the light absorption characteristics and found that Zr2CO2 shows the highest absorption (similar to 12.25 x 10(5) cm(-1)), followed by Zr2CF2, Zr2NO2, and Zr2NF2. Compared to Zr2XO2, Zr2XF2 exhibits nearly twice the optical reflection. The relatively lower reflection and refraction observed in O-terminated MXenes can be linked to their semiconductor-like behavior, where incident light is mainly absorbed by electrons transitioning from lower to higher energy states in the electronic structure. The findings of our study demonstrate the promising potential of these Zr2XT2-based MXenes for applications in optoelectronics.