Extended Data Fig. 1: Surface exchange reaction of Ti3C2 MXenes with amines and thermal degradation analysis of h-MXenes.
a, X-ray fluorescence (XRF) spectral and elemental analysis for the Ti3C2Br2 and Ti3C2(bua)2/3 MXenes. XRF spectra were normalized according to Ti Kα1. Based on XRF analysis, Br was completely removed after the surface modification with deprotonated butylamine. b, Powder XRD patterns of products after treatment of Ti3C2Br2 with butylamine and NaH at 120 °C for 2 days, as well as the products of control experiments. We observed that Ti3C2Br2 barely reacted with NaH in an inert solvent at 120 °C. When treated only with butylamine at 120 °C, Ti3C2Br2 is likely to be partially converted or intercalated, as a new peak at 5.4° has emerged, but the majority of Ti3C2Br2 is still intact. When butylamine was deprotonated by NaH and then reacted with Ti3C2Br2, the (0 0 0 2) peak shifted to 4.65° while the \((1 1 \overline{2} 0)\) peak shifted to 60.9°. The absence of diffraction peaks from Ti3C2Br2 suggests the reaction was complete, which was confirmed by XRF analysis. c, Powder XRD patterns of Ti3C2Br2 before and after treatment with triethylamine and NaH at 120 °C for 2 days: The XRD pattern is unchanged, which indicates that no reaction occurred and suggests that deprotonation of amines is crucial to promoting the exchange reaction on MXene surfaces. d, TGA characterization of Ti3C2(pra)2/3 MXene. The sample was heated from room temperature (25 °C) to 650 °C at a rate of 2 °C min−1 under nitrogen. e, SEM-EDS images of pristine Ti3C2(pra)2/3 and that after heating up from room temperature (25 °C) to designated temperature at a rate of 20 °C min−1 and hold for 1 hour under nitrogen flow. XRD and Raman characterizations of the annealed h-MXenes are shown in Supplementary Fig. 1.
