A Comparative Study on the Gas Capturing and Sensing Properties of Mxene and O-Doped Mxene

Abstract

Very recently, Michałowski et al. (Nature Nanotechnology, 2022, 171192), reported the existence of O-doped MXene for the first time. To investigate the impact of O doping on the surface chemical properties of MXene materials, we explore the adsorption behaviors of common gas molecules on the surface of M3C2O2 (M = Ti, Zr and Hf) and O-doped M3C2O2 (O@M3C2O2) by using first-principles calculations. Our results revealed that Zr3C2O2 and Hf3C2O2 with and without O doping can effectively capture NH3 with the adsorption energies lower than -0.50 eV. Interestingly, the O doping can significantly enhance the adsorption strength of NO2 on Zr3C2O2 and Hf3C2O2, with the corresponding adsorption energies decrease from -0.18 and -0.40 eV into -0.39 and -1.02 eV, respectively. In particular, the adsorption of NO2 can obviously alter the work functions of O@Zr3C2O2, O@Hf3C2O2, and Hf3C2O2 implying their high sensitivities toward NO2. Besides, the applied strains can effectively regulate the adsorption strength of NH3 and NO2 on the surfaces of Zr3C2O2 and Hf3C2O2 with and without O doping, indicating the potential applications of these monolayers in the storage and separation of NH3 and NO2. Our results will be very helpful in understanding the surface chemical properties of O-doped MXenes.

Keywords: Keywords: MXene, Oxygen Doping, Strain, Gas sensor, Gas capturer