Ti3C2Tx MXene Quantum Dots with Surface-Terminated Groups (-F, -OH, =O, -Cl) for Ultrafast Photonics

Abstract

Transition metal carbides and nitrides (MXenes) have attracted significant attention in photoelectric applications due to their highly tunable electronic and optical properties influenced by a flexible compositional or surface functional group regulation. Ti3C2Tx MXenes (-F, -OH, =O terminated) used in previous ultrafast photonic studies are usually synthesized via a generic hydrofluoric acid (HF) etching strategy, which may cause numerous defects and thus impedes the optoelectronic properties of Ti3C2Tx. In this contribution, inspired by a much higher conductivity and carrier mobility of Ti3C2Tx (-F, -OH, =O, -Cl terminated) prepared from a minimally intensive layer delamination method (MILD) etching strategy, we further optimized it with a liquid-phase exfoliation (LPE) method to synthesize pure Ti3C2Tx quantum dots (QDs) for ultrafast photonic. Compared to the other QDs saturable absorber (SA) devices performed at 1550 nm, our SA device exhibited a relatively low saturation intensity (1.983 GW/cm−2) and high modulation depth (11.6%), allowing for a more easily mode-locked pulse generation. A distinguished ultrashort pulse duration of 466 fs centered at the wavelength of 1566.57 nm with a fundamental frequency of 22.78 MHz was obtained in the communication band. Considering the SA based on such a Ti3C2Tx QDs tapered fiber is the first exploration of Er3+-doped fiber laser (EDFL), this work will open up a new avenue for applications in ultrafast photonics.

N-terminalized titanium carbide MXene coupled with graphene oxide toward optimized temporal domain-dependent nonlinear absorption

“…On the other hand, recent research has generated considerable interest in attributing the RSA of Ti 3 C 2 T x MXene to mechanisms such as 2PA, bandgap renormalization, and ESA of surface functional groups. 20,25,31,48 Under the irradiation at 532 nm in the ns regime and at 800 nm in the fs regime, the log(DT 0 )-log(I) diagram was used to investigate the relationship between the NLO absorption (DT 0 , the depth of the valley bottom) and the laser pulse energy density (I) in Ti 3 C 2 T x MXene. The slope is correlated with the order of the nonlinear optics, corresponding to the slope of n, which is a nominal (n + 1) photon absorption process.…”

“…44 Additionally, distinct surface functional group terminations on Ti 3 C 2 T x exhibit varying work functions, 45,46 profoundly influencing its optical and electronic properties, which provides an effective avenue to enhance the optical nonlinearity of Ti 3 C 2 T x nanosheets. 47,48 Recent research from our group has unveiled that switching the NLO performance of Ti 3 C 2 T x nanosheets is linked to the intrinsic surface terminals via electrical modulation, oscillating between the -OH-rich and QO-rich states. 24 Inspired by this concept, we introduce a novel approach to design the NLO-active Ti 3 C 2 T x nanosheets, involving the exchange of surface functional groups followed by the covalent modification, for the first time.…”