Bifunctional Amine- and Thiol-Modified Ti₃C₂T_x MXene for Trace Detection of Heavy Metals

Abstract

Surface functionalization of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides, also known as MXenes, is a powerful approach for modification of their physical and chemical properties for new applications. In this study, we demonstrate the synthesis of a bifunctional Ti3C2T x MXene modified with amine and thiol groups through a facile condensation reaction. We successfully employed the resulting NH2/SH-Ti3C2T x MXene as a solid phase in the ultrasonic-assisted dispersive micro solid-phase extraction (d-μ-SPE) method for the analytical determination of heavy metals at trace levels in food and soil samples. The prepared NH2/SH-Ti3C2T x MXene showed remarkable performance in the ultrasonic-assisted d-μ-SPE method with limits of detection of 0.12 and 2.30 ng mL–1, with linear dynamic ranges of 0.50–90 μg L–1 and 10–120 μg L–1 for cadmium (Cd2+) and lead (Pb2+) ions, respectively. Furthermore, the extraction efficiencies were greater than 97%, with a relative standard deviation of less than 3% for five separate batch experiments in the determination of 5.0 μg L–1 of Cd2+ and Pb2+. This study shows that NH2/SH-Ti3C2T x can be used as a simple, rapid, reliable, selective, and sensitive material in the d-μ-SPE method for the trace determination of Cd2+ and Pb2+ in soil and agricultural products. This study demonstrates the utility of MXenes for analytical chemistry and suggests that further advances in methods for the functionalization of MXenes can open new applications for these already exciting materials.

Synergistic Effect of TiS3 and Ti3C2Tx MXene for Temperature-Tunable p-/n-Type Gas Sensing

“…Ti 3 C 2 T x MXene flakes were prepared using the minimally intensive layer delamination (MILD) method; see the Experimental Section for details. Details of the materials characterization of Ti 3 C 2 T x MXene flakes from similar batches by a variety of techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, ultraviolet–visible (UV–vis) absorption spectroscopy, and various microscopic techniques can be found in our recent publications. − Overall, these characterization results were standard for Ti 3 C 2 T x MXene, so here we only focus on the discussion of the data that are relevant for this sensor study. Notably, Figure b (left) shows an SEM image of the as-synthesized Ti 3 C 2 T x , which demonstrates that the flakes were well exfoliated and over 10 μm in lateral size.…”

Interlayer Incorporation of A-Elements into MXenes Via Selective Etching of A′ from Mn+1A′1–xA″xCn MAX Phases

“…Ti 3 AlC 2 MAX phase was synthesized according to the previously reported procedure. 57 In brief, TiC, Ti, and Al were mixed at a molar ratio of 2:1:1.2 using a pestle and mortar and annealed at 1450 °C for 4 h under the flow of Ar (300 sccm). The same approach was taken for the synthesis of Ti 3 Al 0.75 Sn 0.25 C 2 MAX phase, with the molar ratio being 2:1:0.85:0.25 for TiC/Ti/Al/Sn.…”

“…Ti 3 AlC 2 MAX phase was synthesized according to the previously reported procedure . In brief, TiC, Ti, and Al were mixed at a molar ratio of 2:1:1.2 using a pestle and mortar and annealed at 1450 °C for 4 h under the flow of Ar (300 sccm).…”

High-yield fabrication of electromechanical devices based on suspended Ti3C2Tx MXene monolayers

“…, X is carbon and/or nitrogen, n = 1, 2, 3, or 4, and T x represents the surface functional groups. 17–19 More than 30 different MXenes have been demonstrated experimentally, and many others have been predicted theoretically. 17 Second, long before MXenes were discovered as a new family of 2D materials, 20 bulk transition metal carbides had already been known for their exceptional mechanical properties.…”

“…First, MXenes are known for a great chemical diversity as a very large family of 2D carbides, nitrides, and carbonitrides with a general formula of M n+1 X n T x , where M is a transition metal, such as Ti, Nb, V, Cr, etc., X is carbon and/or nitrogen, n = 1, 2, 3, or 4, and T x represents the surface functional groups. [17][18][19] More than 30 different MXenes have been demonstrated experimentally, and many others have been predicted theoretically. 17 Second, long before MXenes were discovered as a new family of 2D materials, 20 bulk transition metal carbides had already been known for their exceptional mechanical properties.…”