Reviewing MXenes for Plasmonic Applications: Beyond Graphene

MXenes are an emerging class of two-dimensional (2D) materials consisting of carbides, nitrides or carbonitrides of early transition metals. Due to the metallic type of conductivity of MXenes and their 2D structure, they are an ideal candidate to replace the conductive materials currently used in plasmonics, especially graphene. However, the use of MXenes for plasmonics and metamaterials is in its embryonal stage and practically all relevant publications appeared in the last few years. In this contribution we first consider some methods of MXenes fabrication. We continue by analyzing the optical and electronic properties of MXenes of interest for plasmonics (especially spectral dispersion of complex relative dielectric permittivity). We proceed by reviewing some reported applications of MXenes in plasmonics, including among others conventionally designed chemical and biological sensors based on surface plasmon resonance (SPR), metasurface-based optical absorbers and MXene-based nanoantennas, as well as some possible applications in nonlinear optics. In addition to that, we propose some novel uses of MXenes in plasmonics, including chemical and biological nanosensors, superabsorbers with a variable widths of the nanoholes, etc. It is our opinion that the applications of MXenes in plasmonics introduced until now are only scratching the surface of a vast bulk of potential practical devices, structures and effects.