title: Flexible two-dimensional Tin+1Cn (n = 1, 2 and 3) and their functionalized MXenes predicted by density functional theories.
abstract: Two-dimensional (2D) transition metal carbides/nitrides Mn+1Xn labeled as MXenes are attracting increasing interest due to promising applications as Li-ion battery anodes and hybrid electro-chemical capacitors. To realize MXenes devices in future flexible practical applications, it is necessary to have a full understanding of the mechanical properties of MXenes under deformation. In this study, we extensively investigated the stress-strain curves and the deformation mechanisms in response to tensile stress by first principles calculations using 2D Tin+1Cn (n = 1, 2 and/or 3) as examples. Our results show that 2D Ti2C can sustain large strains of 9.5%, 18% and 17% under tensions of biaxial and uniaxial along x and y, respectively, which respectively increase to 20%, 28% and 26.5% for 2D Ti2CO2 due to surface functionalizing oxygen, which is much better than graphene (15% biaxial). The failure of 2D Tin+1Cn MXene is due to the significant collapse of the surface atomic layer; however, surface functionalization could slow down this collapse, resulting in the improvement of mechanical flexibility. We have also discussed the critical strains and Young's modulus of 2D Tin+1Cn and Tin+1CnO2. Our results provide an insight into the microscopic deformation mechanism of MXenes and hence benefit their applications in flexible electronic devices.
authors.affiliation: School of Materials Science and Engineering, and Center for Integrated Computational Materials Engineering, International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China. zmsun@buaa.edu.cn.
authors.forename: Zhonglu
authors.initials: Z
authors.lastname: Guo
authors.forename: Jian
authors.initials: J
authors.lastname: Zhou
authors.forename: Chen
authors.initials: C
authors.lastname: Si
authors.forename: Zhimei
authors.initials: Z
authors.lastname: Sun