Modified two-step etching method for the synthesis of Ti₃C₂ MXene with enhanced electrochemical performance

This work presents a modified etching method for the synthesis of Ti3C2 MXene. The process involves two steps: washing Ti3AlC2 with a low concentration of HF and etching Ti3AlC2 with varying concentrations of FeCl3. FeCl3 can etch the Al layers of Ti3AlC2 by a metal displacement reaction at room temperature, resulting in Ti3C2 nanosheets with an accordion-like morphology. The obtained Ti3C2 MXene was tested as a working electrode for supercapacitors, achieving a maximum specific capacitance of 213.2F/g at 0.5 A/g in a 6 M KOH electrolyte solution, which is higher than that of a Ti3C2 electrode without modification. The method is simple, efficient and reduces the use of HF. This work shows the possibility of synthesizing various MXene-based frameworks using metallic cations with higher redox potentials.