Improving the performance of a titanium carbide MXene in supercapacitors by partial oxidation treatment

Abstract

MXenes are a family of two-dimensional (2D) transition metal carbides, nitrides and carbonitrides that are supposed to be promising materials for high pseudocapacitive energy storage. It has been proven that Ti₃C₂T_x (T_x refers to –F, O, –Cl and –OH) MXenes with more O-termination could exhibit better performance in pseudocapacitors. However, direct oxidation modification would result in the serious oxidation of Ti₃C₂T_x into titanium dioxide. Here we report the controllable oxidation of Ti₃C₂T_x by readily adjusting the loading of ammonium persulfate, in order to turn the –F terminal groups to –O terminal groups on the Ti₃C₂T_x MXene. The partially oxidized Ti₃C₂T_x achieved a high capacitance of 303 F g⁻¹ at 2 mV s⁻¹, and 96.6% capacity can remain even after 9000 cycles. Hence, the controllable oxidation modification of Ti₃C₂T_x could be a promising strategy for surface modification of MXenes.