Aryl Diazonium-Assisted Amidoximation of MXene for Boosting Water Stability and Uranyl Sequestration via Electrochemical Sorption

Abstract

Despite that two-dimensional transition metal carbides and carbonitrides (MXenes) are burgeoning candidates for remediation of environmental pollutants, the construction of robust functionalized MXene nanosheets with a high affinity for target heavy metal ions and radionuclides remains a challenge. Here we report the successful placement of amidoxime chelating groups on Ti 3 C 2 T x MXene surface by diazonium salt grafting. The introduction of amidoxime functional groups significantly enhances the selectivity of Ti 3 C 2 T x nanosheets for uranyl ions and also greatly improves their stability in aqueous solution, enabling efficient, rapid, and recyclable uranium extraction from aqueous solutions containing competitive metal ions. Benefiting from the excellent conductivity of MXenes, the amidoxime functionalized Ti 3 C 2 T x nanosheets show outstanding electrochemical performance such that when loaded on carbon cloth the application of an electric field increases the uranium adsorption capacity from 294 to 626 mg/g, outperforming all organic electrochemical sorption materials reported previously. The present work provides an effective strategy to functionalize MXene nanosheets with fundamental implications for the design of MXene-based selective electrosorption electrode materials. Figure 2. XPS spectra of Ti 3 C 2 T x nanoflakes before and after grafting. High-resolution O 1s region of (a) TC and (b) G-TC and N 1s region of (c) G-TC and (d) F-TC.

Progress and biomedical applications of MXenes

“…Thus, the uranium can be extracted from aqueous solutions containing competitive metal ions in an efficient, fast, and recyclable way (Figure 5B). [ 72 ] Apart from above, Liang et al. triggered the Fenton‐based nano‐catalytic reaction on 2D titania carbide (Ti 2 C 2 ) MXenes nanosheets.…”

“…Reproduced with permission. [ 72 ] Copyright 2020, American Chemical Society. C, Schematic illustration of lipase immobilization through covalent bonding.…”

Recent Advanced on the MXene–Organic Hybrids: Design, Synthesis, and Their Applications

“…In 2020, Zhang et al first proposed a detailed reaction mechanism between aryl diazonium salts and Ti 3 C 2 T x MXene, in which the aromatic primary amine can undergo a diazotization reaction and the produced diazonium salts will covalently bond with MXenes. As shown in Figure 2b, the detailed reaction mechanism can be divided into three steps [37,38]: (1) an electron was transferred from Ti 3 C 2 T x MXene to aryl diazonium salt, which resulted in the cleavage of diazonium to nitrogen and aromatic free radical; (2) the aromatic free radical received an additional H atom from Ti 3 C 2 T x MXene, generating a Ti-O radical on the surface of MXene; (3) strong Ti-O-C covalent bonds formed between Ti-O radical and aromatic free radical. In fact, sulfanilic acid diazonium salts were introduced to get large-scale delaminated Ti 3 C 2 T x multilayers as early as 2016 [39][40][41].…”

“…As another kind of common-used organic molecules, alkylammonium salts including dodecyl trimethyl ammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), cetyltrimethylammonium bromide (CTAB), stearyl trimethyl ammonium bromide (STAB), octadecyl trimethyl ammonium bromide (OTAB), dioctadecyl dimethyl ammonium chloride (DDAC), dihexadecyl dimethyl ammonium bromide (DDAB), and DHT are usually used to insert in MXene layers through electrostatic adsorption. After pillared Reproduced with permission [38]. Copyright 2020, American Chemical Society.…”

“…Copyright 2018, Royal Society of Chemistry. (b) Proposed mechanism of amidoxime functionalization for MXene Ti 3 C 2 T x ;Reproduced with permission[38]. Copyright 2020, American Chemical Society.…”