Electrochemical Properties of Ordered, Two-Dimensional, Double Transition Metals Carbides (MXenes)

Two dimensional (2D) transition metal carbides (MXenes) are a new family of nanomaterials with a very high potential as electrode materials for batteries and electrochemical capacitors (ECs). These materials are labeled MXene because they are obtained by selectively etching of the A-layers from their 3D layered, parent compounds the Mn+1AXn, or MAX, phases, where M is an early transition metal, A is an A-group element, such as Al or Si, X is carbon and/or nitrogen and n is 1 to 3. The excellent performance of MXenes as electrode materials for ECs was recently reported in the case of Ti₃C₂.^1,2 Here, we report on the synthesis and electrochemical properties of the ordered MXenes, Mo₂TiC₂ and Mo₂TiC₃, wherein the Mo atoms are on the surface and the Ti atoms are between the Mo. The volumetric capacitance of freestanding electrodes fabricated by vacuum filtration of 2D Mo₂TiC₂ sheets, was about 400 F/cm³.

(1)      Lukatskaya, M. R.; Mashtalir, O.; Ren, C. E.; Dall’Agnese, Y.; Rozier, P.; Taberna, P. L.; Naguib, M.; Simon, P.; Barsoum, M. W.; Gogotsi, Y. Cation Intercalation and High Volumetric Capacitance of Two-Dimensional Titanium Carbide. Science (80-. ). 2013, 341, 1502–1505.

(2)      Ghidiu, M.; Lukatskaya, M. R.; Zhao, M.-Q.; Gogotsi, Y.; Barsoum, M. W. Conductive two-dimensional titanium carbide “clay” with high volumetric capacitance. Nature 2014, 516, 78–81.