Covalently N-Doped MXene Quantum Dots for Highly Stable Fluorescent Cu²⁺ Ion Sensor

Abstract

MXene quantum dots (MQDs) have excellent photoelectrochemical properties and are attracting considerable attention in the academic field. In this study, we synthesized amino-rich MQDs on the surface by modifying the Ti 3 C 2 nanosheets with 3-aminopropyltriethoxysilane (APTES) and then cutting the functional nanosheets into quantum dots by hydrothermal reaction. The N-MQDs were characterized by UV−vis spectrophotometry, Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The prepared N-MQDs had an average particle size of 8.63 nm. The N-MQDs exhibited excellent linearity and sensitivity for the detection of Fe 3+ and Cu 2+ ions over a concentration range of 0.5−500 μM. The limits of detection (LODs) for the Fe 3+ and Cu 2+ ions were calculated to be 0.17 and 0.15 μM, respectively. Compared with previous N-doped Ti 3 C 2 MQDs, our prepared N-MQDs possessed lower LOD for the detection of Cu 2+ ions. The quantum dot showed a potential to detect Cu 2+ ions in water samples with sodium hexametaphosphate (SHPP) as a Fe 3+ ions masking agent. N-doped MQDs can enhance the fluorescence quantum yield and detection sensitivity for metal ions over that of MQDs without amination. N-MQDs prepared by the method with active amino groups and high stability than previous works, which can expand the application of MQDs in other fields. This study also opens an avenue for the covalent modification of MXene QDs materials and surface engineering fields.

Interface‐Anchored Covalent Organic Frameworks@Amino‐Modified Ti3C2Tx MXene on Nylon 6 Film for High‐Performance Deformable Supercapacitors

“…The C=N vibration peak (1530 cm −1 ) and the C‐C=N−C stretching peak (1250 cm −1 ) from COF and ‐OH stretching vibration peak (3300 cm −1 ) from Ti 3 C 2 T x can be detected in two curves, suggesting the favorable combination degree of COF@N‐Ti 3 C 2 T x /DPA and COF@Ti 3 C 2 T x /DPA film [31,32] . After decorating by Aptes, a new peak at around 864 cm −1 , belonging to Ti−O−Si bond can be measured in COF@N‐Ti 3 C 2 T x /DPA film [34] . Meanwhile, the characteristic peaks at 2930 cm −1 ascribed to the bending asymmetric vibrations of C−H bonds in the alkyl chain of Aptes.…”

Interface‐Anchored Covalent Organic Frameworks@Amino‐Modified Ti3C2Tx MXene on Nylon 6 Film for High‐Performance Deformable Supercapacitors

“…[31,32] After decorating by Aptes, a new peak at around 864 cm À 1 , belonging to TiÀ OÀ Si bond can be measured in COF@N-Ti 3 C 2 T x /DPA film. [34] Meanwhile, the characteristic peaks at 2930 cm À 1 ascribed to the bending asymmetric vibrations of CÀ H bonds in the alkyl chain of Aptes. Additionally, the X-ray photoelectron spectroscopy (XPS) spectra is also performed to investigate the composition and bonding mechanism of samples.…”

Trends in Using Fluorescent MXene Quantum Dots for Selective Detection and Bioimaging Applications: A Review

“…Guan et al detected Cu 2+ ions with nitrogen- and phosphorus-functionalized Ti 3 C 2 Mxene QDs via fluorescence quenching, and it was supported by the inner filter effect . Blue fluorescent covalently nitrogen-doped Ti 3 C 2 QDs were applied for Cu 2+ ions sensing by Wan et al as shown in Figure A . First, they prepared aminated Ti 3 C 2 nanosheets using 3-aminopropyltriethoxysilane (APTES).…”

“…(C) The relation curve between (F 0 – F)/F 0 and different concentrations (0.5–100 and 100–400 μM) of Cu 2+ ions. Reprinted with permission from ref . Copyright 2022, American Chemical Society.…”