Enhanced photocatalytic and spintronic properties in proposed α-MXene family via ferroelectric effect

Two-dimensional transition metal carbides (MXenes) have garnered significant attention due to their distinctive physical and chemical properties. In this study, utilizing density functional theory calculations, we introduce a novel phase of transition metal carbide with the space group of R 3 m , designated as α-MXene with the chemical formula M 2 CX 2 (M ​= ​Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn; X ​= ​O, F). Notably, α-MXene possesses an ABBCA atomic layer configuration closely resembles the two-dimensional ferroelectric material α-In 2 Se 3 , distinct from the close packing ABCAB atomic stacking observed in typical MXenes. It is highlighted that α-MXene exhibits adjustable ferroelectric properties with moderate polarization reversal energy barriers, including five rare ferroelectric metals and one Dirac-semimetal. Moreover, α-MXenes not only enable photocatalytic reactions by utilizing infrared light to overcome the band gap restriction of 1.23 ​eV, but also generate hydrogen and oxygen gases on separate surfaces due to electric field induced by ferroelectric effect. Additionally, ferroelectric tunnel junctions (FTJs) based on α-MXene show exceptionally high tunneling electroresistance ratios (TERs), indicating their suitability for advanced ferroelectric memory device applications. Our research provides a viable strategy for exploring ferroelectric materials within the expansive MXene family and exemplifies the applications of α-MXenes in photocatalysis and spintronics.