Effect of Ultrafast Broadband Nonlinear Optical Responses by Doping Silver into Ti3C2 Nanosheets at Visible Spectra

Abstract

Ti3C2 nanosheet is a newly discovered two-dimensional (2D) clan. It turns out to have encouraging applications for electromagnetic shielding and energy storage. Here, Ag@ Ti3C2 hybrids are precisely synthesized by using the one-step solution processing method. Also, their ultrafast broadband nonlinear optical responses in the visible region are studied systematically through nanosecond open-aperture Z-scan and transient absorption techniques. The mechanism of two-photon absorption (TPA) is disclosed in the visible region (409–532 nm). When the laser energy is low and the wavelength is longer than 400 nm, nonlinear absorption cannot happen. Meanwhile, as the laser energy increases, two photons will be absorbed by the electrons in the valence band and the electrons will jump to the conduction band. The process is named as two-photon absorption which will make the specimen show reverse saturable absorption (RSA) properties. What is more, the ultrafast carrier dynamics of the specimen are studied by using the transient absorption. The result shows that the decay contains two phases: the fast and then the slow one. The two phases first come from electron–phonon and then from phonon–phonon interactions, respectively. The electron transfer and charge carrier trapping processes are further verified by the outcomes of similar measurements on Ag@ Ti3C2 hybrids. Besides, the two decay processes increase together with the pump fluence. These results show that Ti3C2 nanosheet has potential applications in broadband optical limiter.

Ga2O3–MXene Nanowire Networks with Enhanced Responsivity for Deep-UV Photodetection

“…However, the diffraction peaks of Ti 3 C 2 T x are shifted to a relatively lower position than the standard peaks. For example, the peak at 7.2° (an interplanar spacing of 12.26 Å) is assigned to the (002) planes of Ti 3 C 2 T x , , which is lower than that of Ti 3 AlC 2 (9.4° for (002) planes), indicating the expansion of interlayer distance after etching with HCl/KF according to the Bragg equation (2 d sin θ = n λ, n = 1,2···). Also, the characteristic peak at 39° of Ti 3 AlC 2 disappears, implying the complete removal of the Al element in Ti 3 C 2 T x . ,, As for Ga 2 O 3 –5Ti 3 C 2 T x , the diffraction peaks of Ga 2 O 3 can be seen, and the diffraction peaks at 7.1 and 28.2° can also be indexed to the (002) and (006) planes of Ti 3 C 2 T x .…”

“…29 However, the diffraction peaks of Ti 3 C 2 T x are shifted to a relatively lower position than the standard peaks. For example, the peak at 7.2°(an interplanar spacing of 12.26 Å) is assigned to the (002) planes of Ti 3 C 2 T x, 30,31 which is lower than that of Ti 3 AlC 2 (9.4°for (002) planes), 32 indicating the expansion of interlayer distance after etching with HCl/KF 31 The recombination condition of photogenerated electrons and holes is estimated by the PL emission spectra at 254, 280, 300, 330, and 365 nm (Figures 5b and S4) using a mixed solution of deionized water and triethanolamine (v/v = 3:1) as the dispersion solvent. The lower the intensity of the PL curve, the longer the lifetime of the photogenerated electrons.…”

Two-Dimensional Nb4AlC3 (MAX) and Nb4C3 (MXene): Excellent Optical Limiting Materials with Oppositely Applicated Waveband

“…For example, a number of metal nanoparticles and semiconductors have been found to exhibit excellent OL responses to nanosecond laser pulses . Similarly, carbon nanomaterials such as carbon black suspensions and carbon nanotubes have been used for OL materials and other NLO applications. − However, studies on the OL properties of the MXene family are fewer and mainly focused on the visible to SWIR wavelengths, − and there are no reports on the OL properties of 2D Nb 4 AlC 3 and 2D Nb 4 C 3 too, as far as we know.…”

“…31 In addition, Ti 3 C 2 has been studied in the fields of photocatalysis, 32 energy conversion and storage, 33,34 biomedical, 35 and nonlinear optics. 36,37 In 2020, Wang et al investigated the broadband nonlinear optical response of Nb 2 C in the wavelength range of 400−1600 nm. The results showed that Nb 2 C exhibits saturable absorption (SA) properties in the UV band and TPA properties in the SWIR band.…”

“…In 2019, Cui et al successfully etched Ti 3 AlC 2 with HCl and LiF solutions to obtain Ti 3 C 2 nanosheets, which have a smaller reflection loss value (−27.5 dB) at 17.1 GHz than Ti 3 AlC 2 , indicating that Ti 3 C 2 is a promising material for electromagnetic absorption . In addition, Ti 3 C 2 has been studied in the fields of photocatalysis, energy conversion and storage, , biomedical, and nonlinear optics. , In 2020, Wang et al investigated the broadband nonlinear optical response of Nb 2 C in the wavelength range of 400–1600 nm. The results showed that Nb 2 C exhibits saturable absorption (SA) properties in the UV band and TPA properties in the SWIR band.…”