MXene (Ti3C2Tx) nanosheets were synthesized and delaminated according to the modified LiF/HCl method (42). The etching solution was prepared by dissolving 3.2 g of lithium fluoride (LiF) into 30 ml of 9 M hydrochloric acid (HCl). Then, 2 g of Ti3AlC2 powder (≥98%; Famouschem Technology Co. Ltd.) was slowly added into the etching solution over the course of 5 min with agitation of a magnetic stir bar. The etching process continued for 12 hours under magnetic stirring at room temperature. Thereafter, the reaction products were washed with DI water and centrifuged for several cycles under 10,000 rpm until reaching a pH value between 5 and 6. The sediment was then subjected to sonication with Ar gas bubbling for 1 hour, after which dispersion was carried out in the centrifuge at 3000 rpm for 30 min to eliminate the unexfoliated Ti3C2Tx MXene sheets. Last, the MXene nanosheet solution was obtained and stored at 4°C until use.