Green MXene Turtle Babak Anasori, Michael Naguib, Yury Gogotsi, Michel W. Barsoum Department of Materials Science and Engineering, and A.J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, PA 19104, USA Two-dimensional Ti3C2 layers with surface groups of OH and/or F were formed by immersing Ti3AlC2 powder in concentrated hydrofluoric acid which results in selective etching of the Al layers. Since Ti3AlC2 is a member of a large family of layered, ternary carbides and nitrides called MAX phases, this discovery opens the door to synthesis of a large number of 2-D solids with different chemistries that can be manipulated to tune properties. 500nm Scanning Electron Microscopy