Characterizing the Chemical Structure of Ti 3 C 2 T x MXene by Angle-Resolved XPS Combined with Argon Ion Etching.

Angle-resolved XPS combined with argon ion etching was used to characterize the surface functional groups and the chemical structure of Ti 3 C 2 T x MXene. Survey scanning obtained on the sample surface showed that the sample mainly contains C, O, Ti and F elements, and a little Al element. Analyzing the angle-resolved narrow scanning of these elements indicated that a layer of C and O atoms was adsorbed on the top surface of the sample, and there were many O or F related Ti bonds except Ti-C bond. XPS results obtained after argon ion etching indicated staggered distribution between C-Ti-C bond and O-Ti-C, F-Ti bond. It is confirmed that Ti atoms and C atoms were at the center layer of Ti 3 C 2 T x MXene, while O atoms and F atoms were located at both the upper and lower surface of Ti 3 C 2 layer acting as surface functional groups. The surface functional groups on the Ti 3 C 2 layer were determined to include O 2- , OH - , F - and O - -F - , among which F atoms could also desorb from Ti 3 C 2 T x MXene easily. The schematic atomic structure of Ti 3 C 2 T x MXene was derived from the analysis of XPS results, being consistent with theoretical chemical structure and other experimental reports. The results showed that angle-resolved XPS combing with argon ion etching is a good way to analysis 2D thin layer materials.