Hydrochloric acid (hcl)

Mo₂CT_x was prepared by the method previously reported elsewhere.^{10 (link)} Mo₂CT_x was synthesized by selective etching of gallium (Ga, Kojundo Korea, 99.99%) atoms from Mo₂Ga₂C using concentrated hydrofluoric acid (HF, Junsei, 40%). Mo₂Ga₂C was prepared by a solid–liquid reaction between Mo₂C and Ga, in a molar ratio of 1 : 8. The mixture was annealed at 850 °C for 16 hours in a vacuum furnace and cooled down to room temperature, followed by re-annealing at 850 °C for 48 hours to form Mo₂Ga₂C. Then, 2 g of Mo₂Ga₂C was placed in a polypropylene (PP) beaker with 40 ml of concentrated HF and stirred for 6 days to remove Ga atoms. The resultant powder was washed with 1 M hydrochloric acid (HCl, Daejung, 35%) and de-ionized water for several cycles until the pH of ≈ 7 was reached. To obtain delaminated Mo₂CT_x, 1 g of the powder was immersed in 10 ml of tetrabutylammonium hydroxide (TBAOH, Sigma-Aldrich, 57%) for 4 hours, then washed with DI water. 250 ml of DI water was added to the TBAOH-treated powder, and sonicated in an ice bath for 1 hour using a dismembrator. Then 40 ml of the above suspension was transferred to each centrifuge tube, and was centrifuged at 25 000 rpm for 5 min. The resultant supernatant was collected whereas the settled powder was removed.