Defect-Free Few-Layer M C T (M = V, Nb, Ta) MXene Nanosheets: Synthesis, Characterization, and Physicochemical Properties.

High-quality few-layer M C T (M = V, Nb, Ta) MXenes are very important for applications and are necessary for clarifying their physicochemical properties. However, the difficulty in etching for themselves and the existence of MC/MC and M-Al alloy impurities in their M AlC precursors seriously hinder the achievement of defect-free few-layer M C T (M = V, Nb, Ta) MXenes nanosheets. Herein, three different defect-free few-layer M C T (M = V, Nb, Ta) nanosheets are obtained by using a universal synthesis strategy of calcination, selective etching, intercalation, and exfoliation.