context: Ti3C2Tx-based materials have been widely reported as anode materials for supercapacitors and hybrid supercapacitors with the acid electrolyte. Here, the modified Ti3C2Tx MXene (400-KOH-Ti3C2) samples were synthesized based on a previous report. The XRD pattern (Fig. 1a and S1†) reveals that the diffraction peaks of 400-KOH-Ti3C2 shift to a lower 2θ angle compared with those of the original Ti3C2Tx, indicating the increase of interlayer distances after KOH treatment and calcination. In addition, the intensity of partial diffraction peaks for 400-KOH-Ti3C2 is slightly weaker than that of original Ti3C2Tx, suggesting that some feature of the Ti3C2Tx diffraction peaks is shielded by the K+ intercalation into the Ti3C2 MXene layer. Raman spectroscopy (Fig. 1b) and XPS tests (Fig. S2†) were carried out to further manifest the purity and chemical composition of the as-obtained 400-KOH-Ti3C2 samples. To clearly reflect the interlayer spacing for 400-KOH-Ti3C2 samples, the SEM and TEM images are given in Fig. S3† and 1c, respectively. It can be found that 400-KOH-Ti3C2 consisted of stacked MXene nanosheets. The corresponding HRTEM image shows that the interlayer distance of 400-KOH-Ti3C2 is 1.17 nm (Fig. 1d), much larger than that of the original Ti3C2Tx (0.98 nm, Fig. S4†), further confirming the expansion of the interlayer distance after KOH treatment and calcination. In addition, the scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) mapping images of 400-KOH-Ti3C2 clearly indicate that Ti, C, O, F and K elements are homogeneously distributed in all MXene sheets (Fig. S5†).
answer: Ti3C2Tx-based materials