First principles study on geometric and electronic properties of two-dimensional Nb₂CΕ_x MXenes

【摘要】 MXenes are a new type of two-dimensional carbides with rich physical and chemical properties. The physics of MXenes, and thus the applications, are dominated by surface functional groups. Herein, the effects of different terminations（O,S, Se, Te） on the geometric and electronic properties of Nb₂C MXenes were studied via density functional theory（DFT）calculations. Three adsorption sites were examined to determine the most stable configurations. The results showed that both the types and the positions of surface functional groups influence the geometric stability and physical characters of Nb₂C. The S and Se terminations make the Nb₂C MXenes to be semiconductor, while Nb₂C MXenes with other terminations（O, Te） are conductor. The electron location function, density of states, Bader charge distribution, and the projected crystal orbital Hamilton population were conducted to explain the origin of adsorption stability and electronic nature difference. Our results provide a fundamental understanding about the effects of surface terminations on the intrinsic stability and electronic properties of Nb₂C MXenes.更多还原

【Abstract】 MXenes are a new type of two-dimensional carbides with rich physical and chemical properties. The physics of MXenes, and thus the applications, are dominated by surface functional groups. Herein, the effects of different terminations（O,S, Se, Te） on the geometric and electronic properties of Nb₂C MXenes were studied via density functional theory（DFT）calculations. Three adsorption sites were examined to determine the most stable configurations. The results showed that both the types and the positions of surface functional groups influence the geometric stability and physical characters of Nb₂C. The S and Se terminations make the Nb₂C MXenes to be semiconductor, while Nb₂C MXenes with other terminations（O, Te） are conductor. The electron location function, density of states, Bader charge distribution, and the projected crystal orbital Hamilton population were conducted to explain the origin of adsorption stability and electronic nature difference. Our results provide a fundamental understanding about the effects of surface terminations on the intrinsic stability and electronic properties of Nb₂C MXenes.更多还原