A Family of 2D-MXenes: Synthesis, Properties, and Gas Sensing Applications

Abstract

Gas sensors, capable of detecting and monitoring trace amounts of gas molecules or volatile organic compounds (VOCs), are in great demand for numerous applications including diagnosing diseases through breath analysis, environmental and personal safety, food and agriculture, and other fields. The continuous emergence of new materials is one of the driving forces for the development of gas sensors. Recently, 2D materials have been gaining huge attention for gas sensing applications, owing to their superior electrical, optical, and mechanical characteristics. Especially for 2D MXenes, high specific area and their rich surface functionalities with tunable electronic structure make them compelling for sensing applications. This Review discusses the latest advancements in the 2D MXenes for gas sensing applications. It starts by briefly explaining the family of MXenes, their synthesis methods, and delamination procedures. Subsequently, it outlines the properties of MXenes. Then it describes the theoretical and experimental aspects of the MXenes-based gas sensors. Discussion is also extended to the relation between sensing performance and the structure, electronic properties, and surface chemistry. Moreover, it highlights the promising potential of these materials in the current gas sensing applications and finally it concludes with the limitations, challenges, and future prospects of 2D MXenes in gas sensing applications.

ROS- and pH-Responsive Polydopamine Functionalized Ti3C2Tx MXene-Based Nanoparticles as Drug Delivery Nanocarriers with High Antibacterial Activity

“…After etching with 40% HF, an accordion-like structure was obtained, possibly because of the high reactivity between the Al atomic layer of Ti 3 AlC 2 and F ions as well as the large amount of escaped H 2 due to the exothermic nature of the HF reaction with aluminum (Figure 3b) [56]. After TBAOH intercalation, ultrathin flakes were observed (Figure 3c) because of the incorporation of the TBAOH intercalator into the interlayer of pristine MXene, which is consistent with a previous report [57]. After functionalization with APTES, an irregular distribution of nanosized flakes (MXene-NH 2 ) was observed, which is probably due to the electrostatic interaction between the amine groups of APTES (Figure 3d).…”

Recent Advances and Perspectives of Lewis Acidic Etching Route: An Emerging Preparation Strategy for MXenes

“…Currently, there are different types of sensors, such as gas sensors, biosensors and sound sensors [245]. Owing to the medium specific surface area, layered structure, rich active sites and superior electronic conductivity, MXenes have been regarded as promising sensitive materials in recent years [44]. For example, Wu et al synthesized Ti 3 C 2 Cl 2 MXene via ZnCl 2 etching in 2021 and investigated its gas-sensing performance [246].…”

“…Furthermore, the surface groups of MXenes mainly comprise of -O, -OH, -F, -Cl, -Br, -I, -S, -Se, -Te, -NH, etc., and can also be adjusted by etchants, termination substitution reaction and storage environment [40][41][42][43]. To date, nearly 50 various MXenes have been experimentally fabricated [44]. Considering the great tunability of M-site atoms, X-site atoms and surface terminations as well as the structural diversity of MXenes (Fig.…”

Room-Temperature Semiconductor Gas Sensors: Challenges and Opportunities

“…Since the pioneering work on mechanically exfoliated graphene, which shows an RT NO 2 -sensitive effect, 2D layered semiconductors such as transition metal dichalcogenides (TMDs), , black phosphorus (BP), , 2D carbides and nitrides (MXenes), , 2D metal–organic frameworks (MOFs), , and covalent organic frameworks (COFs) have become a research hotspot in the gas sensor field.…”