2D V₂AlC (MAX) and V₂C (MXene): Optical limiting materials with opposite wavelength band

MXenes, as emerging class of two-dimensional (2D) materials, has garnered considerable attention in both optical and electrical domains. In this study, the MXene (V 2 C) was synthesized by etching the MAX-phase precursor (V 2 AlC) using a mixture of hydrofluoric acid (HF) and hydrochloric acid (HCl), followed by intercalation with tetrabutylammonium hydroxide solution (TBAH). Furthermore, V 2 AlC and V 2 C nanosheets were fabricated via the liquid-phase exfoliation (LPE) method, and their nonlinear absorption (NLA) properties were systematically investigated across the ultraviolet (UV) to short-wave infrared (SWIR) band. The results demonstrated that 2D V 2 AlC nanosheets exhibited higher two-photon absorption (TPA) coefficients ([Formula: see text], lower OL thresholds, and larger TPA cross sections ([Formula: see text] in the SWIR band. In contrast, V 2 C nanosheets, formed after etching, exhibited superior TPA performance in the UV band, displaying distinctly different nonlinear optical (NLO) behaviors. These findings suggest that both materials possess outstanding optical limiting (OL) performance, with each material offering distinct advantages at specific wavelengths. Overall, V 2 AlC and V 2 C nanosheets hold great promise as advanced OL materials for applications in optical component protection, laser protection for the human eye, and optical filtering.