Chemically Stabilized and Functionalized 2D‐MXene with Deep Eutectic Solvents as Versatile Dispersion Medium

Abstract

2D transition metal carbides and nitrides, namely MXenes, are normally synthesized in acidic solutions and are delaminated in basic solutions. This results in versatile materials with unique physical/chemical properties suitable for various practical applications. However, solution‐based chemical treatments can affect the chemical structures of MXenes, which accelerates the oxidation reactions and degrades their intrinsic properties. Here, long‐term stable Ti3C2Tx dispersion in deep eutectic solvents (DESs) that resisted oxidation degradation for up to 28 weeks is demonstrated. As an anti‐oxidative dispersion medium, DESs helped prevent oxidation of Ti3C2Tx layers due to hydrogen bond accepting and donating molecules passivated surface of the Ti3C2Tx. In addition, DES molecules in bulk solution can also be hydrated in the presence of water, which stabilizes reactive oxygen by forming stable DES‐water cluster. Therefore, the use of DESs enhanced the delamination of the Ti3C2Tx nanosheets, while preventing oxidation of the nanosheets in solution and even in their dried state. As a result, thick and thin films of Ti3C2Tx fabricated using DESs exhibited stable sheet resistance in comparison with pristine‐Ti3C2Tx. In addition, Ti3C2Tx dispersed in DESs can be applied as electrodes for electrochemical capacitors, in which they showed higher chemical stability and better performance than pristine Ti3C2Tx.

Deep Eutectic Solvents for Boosting Electrochemical Energy Storage and Conversion: A Review and Perspective

“…Apart from serving as exfoliation agents, Kim et al used DESs as an antioxidative dispersion medium and surface passivation materials to improve the long-term chemical stability of Ti 3 C 2 T x in water. [128] The DES (1:2 ChCl:EG and ChCl:urea) has a chemical inertness and can be hydrated in water to stabilize the reactive water molecules; therefore, DES can effectively prevent the penetration of oxygen (in water molecules) that cause oxidation of Ti 3 C 2 T x .…”

Interface interaction-mediated design of tough and conductive MXene-composited polymer hydrogel with high stretchability and low hysteresis for high-performance multiple sensing

“…1b. The MXene aqueous dispersion without gelatin shows a dramatic color change from dark green to gray, and the aggregates appear at the bottom of the bottle after 50 days of storage, which can be attributed to the oxidation of MXene to TiO 2 [40]. By contrast, the gelatin-MXene dispersion remains a dark green color with negligible aggregation, similar to its initial state.…”

“…Water molecules and dissolved oxygen in aqueous dispersions have significant influences on the oxidation reaction [36]. Few studies have been committed to improving the stability of MXene using antioxidant agents to resist reactive oxygen [37][38][39][40]. However, there are no reports on effective techniques to eliminate the oxidation of MXene nanosheets in hydrogels.…”

Surface engineering of MXenes for energy and environmental applications

“…For instance, DESs with hydrogen bond accepting and donating molecules can passivate the surface of the Ti 3 C 2 T x and prevent the oxidation reaction. 200 Fig. 19 shows a schematic illustration of the oxidation behavior of Ti 3 C 2 T x .…”