Synthesis and characterization of Cr2C MXenes

MXenes are a large class of materials that are chemically exfoliated from metal–aluminum–carbon (MAX) bulk crystals into low-dimensional sheets. While many MXenes have been theoretically predicted, the careful balance required in the exfoliation between breaking the inter-layer bonds without damaging the intra-layer bonds of the sheets has limited synthesis and experimental study. Here, we developed the synthesis of Cr2C from its parent Cr2AlC MAX phase and showed the etching is optimized using sodium fluoride and hydrogen chloride with a modified minimally intensive layer delamination (mMILD) method in a cold environment of 9 ℃. We further optimized the intercalation and delamination using sonication and washing methods. The resulting Cr2C crystal structure was characterized. These results open up Cr2C to experimental study, including of its predicted emergent magnetic properties, and develop guidelines for synthesizing new MXene materials.