Novel highest-Tc superconductivity in two-dimensional Nb2C MXene

Abstract: Currently, superconductivity in two-dimensional (2D) materials is a hot topic of research owing to their potential technological applications. Here, we report observation of superconductivity in a 2D Nb2C MXene with transition temperature of 12.5 K, which is the highest transition temperature in MXene attained till now. We systematically optimized the chemical etching process to synthesize the Nb2C MXene from its Nb2AlC MAX phase. The X-ray diffraction (XRD) shows a clear (002) peak indicating the successful formation of MXene as well as a significant increase in the c-lattice parameter from 13.83{\AA} to 22.72{\AA} that indicates the delamination of Nb2C MXene sheets as revealed by morphological study using scanning electron microscope. The Meissner effect is detected using superconducting quantum interference device (SQUID: Quantum design). Lower and upper critical fields as a function of temperature follow the Ginzburg-Landau (GL) theory indicating the superconducting nature of the Nb2C MXene. Strong-electron phonon interaction and the large density-of-states at Fermi level may cause the emergence of superconductivity at such a higher transition temperature which has theoretically been predicted for Mo2C MXene. Our work is a significant advancement in the field of research and potential applications of 2D MXene.