MXene Ti₃CNT_x for near-infrared plasmonics and high broadband absorption

Nanostructure-mediated manipulation of light propagation has enabled the demonstration of advanced metamaterial absorbers that have improved the performance of optoelectronic and nanophotonic energy harvesting systems. In this work, MXene Ti₃CNT_x thin films are prepared and demonstrated as an addition to the plasmonic material database in the near-infrared (NIR) region. Additionally, the optical properties of periodic Ti₃CNT_x nanodisk arrays are investigated through both experimental and simulation studies. It is found that the Ti₃CNT_x/Al₂O₃ nanodisk arrays on Ag film exhibit enhanced localized and gap surface plasmon resonance at NIR wavelengths. These resonances are characterized by electric field concentration in the dielectric gap between the MXene and Ag. The synergistic combination of optical losses inherent in Ti₃CNT_x and scattering enhancement at the resonances of the nanoarrays can achieve high and stable light absorption (>95%) in the NIR. The obtained near-perfect absorption (∼99%) at a wavelength of 1.55 μm demonstrates about a 10% improvement over Ti₃C₂T_x nanoarrays. These findings establish Ti₃CNT_x MXene as a promising platform for plasmonic applications and provide critical insights for designing advanced metasurface absorbers.