Ambient oxidation of Ti<sub>3</sub>C<sub>2</sub> MXene initialized by atomic defects

Xia, Fanjie; Lao, Junchao; Yu, Ruohan; Sang, Xiahan; Luo, Jiayan; Li, Yu; Wu, Jinsong

doi:10.1039/c9nr07236e

Cited by 182 publications

(178 citation statements)

References 33 publications

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“…Xia et al [52] reported the oxidation of Ti 3 C 2 T x MXene under ambient conditions (room temperature), where dispersions of synthesized MXenes were stored in tin (Sn)wrapped vials to neglect the probability of light-induced oxidation. Further, the mechanism behind the oxidation of MXene (Ti-based, Ti 3 C 2 T x ) was explored.…”

Section: Oxidative Degradation Of Mxenes and Influencing Parametersmentioning

confidence: 99%

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Improving oxidation stability of 2D MXenes: synthesis, storage media, and conditions

et al. 2021

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Understanding and preventing oxidative degradation of MXene suspensions is essential for fostering fundamental academic studies and facilitating widespread industrial applications. Owing to their outstanding electrical, electrochemical, optoelectronic, and mechanical properties, MXenes, an emerging class of two-dimensional (2D) nanomaterials, show promising state-of-the-art performances in various applications including electromagnetic interference (EMI) shielding, terahertz shielding, electrochemical energy storage, triboelectric nanogenerators, thermal heaters, light-emitting diodes (LEDs), optoelectronics, and sensors. However, MXene synthesis using harsh chemical etching causes many defects or vacancies on the surface of the synthesized MXene flakes. Defective sites are vulnerable to oxidative degradation reactions with water and/or oxygen, which deteriorate the intrinsic properties of MXenes. In this review, we demonstrate the nature of oxidative degradation of MXenes and highlight the recent advancements in controlling the oxidation kinetics of MXenes with several promising strategic approaches, including careful control of the quality of the parent MAX phase, chemical etching conditions, defect passivation, dispersion medium, storage conditions, and polymer composites.

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Section: Oxidative Degradation Of Mxenes and Influencing Parametersmentioning

confidence: 99%

“…Ti atoms in the MXene layers are oxidized to form TiO 2 nanoparticles, whereas C atoms in the MXene layers agglomerate and develop an amorphous carbon structure. The formation of TiO 2 nanocrystals and amorphous carbon is explained by the following equation [52]:…”

Section: Oxidative Degradation Of Mxenes and Influencing Parametersmentioning

confidence: 99%

Improving oxidation stability of 2D MXenes: synthesis, storage media, and conditions

et al. 2021

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“…[ 21,27 ] Other aspects may also contribute to the oxidation of MXenes, such as the amount and types of terminal groups, etching conditions, ultraviolet exposure, and the number of defects on the MXene nanosheets. [ 3,28,29 ]…”

Section: Introductionmentioning

confidence: 99%

pH, Nanosheet Concentration, and Antioxidant Affect the Oxidation of Ti₃C₂T_x and Ti₂CT_x MXene Dispersions

Zhao

Vashisth

Blivin

et al. 2020

Adv Materials Inter

120

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groups (OH, O, F), n usually ranges from 1 to 3, and x reflects the number of terminal groups. [1-5] MXenes have drawn much attention for their potential use in energy storage, [1,6] sensing technology, [7,8] functional coatings, [9-11] plasmonics, [12] and catalytic applications [13-15] due to their high electrical conductivity, hydrophilicity, and surface charge. Most of those properties can be traced back to their metallic-like 2D structure and functional groups attached during the etching and delamination processes. [4,5,16-18] However, recent studies suggest that MXenes are prone to react with dissolved oxygen and water molecules, which results in the formation of transition metal oxides and carbon residues. [3,19,20] Initially, Zhang et al. claimed that MXene oxidizes due to the contact with dissolved oxygen in water. [20] However, Huang et al. and our group also demonstrated that water molecules, rather than oxygen molecules, play a critical role in MXene degradation. [21,22] MXenes were reported to oxidize and degrade more rapidly in water rather than in organic solvents, air, or polymer matrixes. [3,23] Zhang et al., Chae et al., and Habib et al. (our group) also found that temperature and humidity have an influence on MXene oxidation. [3,19,20] They proposed that low temperatures and low humidity can mitigate the oxidation of MXene nanosheets due to the slower reaction kinetics and reduced exposure to water molecules, respectively. In addition, MXene nanosheets that are single-to few-layered or have smaller lateral size oxidize faster than multilayered MXene clay particles or larger-size nanosheets. MXenes oxidize rapidly when exposed to oxidizers such as hydrogen peroxide or treated by flash-annealing at high temperatures. [24,25] In addition, elemental composition may influence the oxidation kinetics. [26] VahidMohammadi et al. and Huang et al. reported that M 2 XT x MXenes, such as V 2 CT x and Ti 2 CT x , oxidize and degrade much faster than the more common M 3 X 2 T x , such as Ti 3 C 2 T x. [21,27] Other aspects may also contribute to the oxidation of MXenes, such as the amount and types of terminal groups, etching conditions, ultraviolet exposure, and the number of defects on the MXene nanosheets.

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“…demonstrated the mechanism of ambient degradation of Ti 3 C 2 MXene where titanium oxide starts to grow in the vicinity of basal and edge atomic defects. [ 109 ] Positively charged titanium vacancies induce the formation of amorphous carbon, while oxidation of Ti cations and the following formation of TiO 2 occur at nearby positions. At the same time, Nb adatoms at the Nb 2 CT x MXene surface contact with ambient O, forming oxide nanoclusters that start to destroy local structural order with following degradation of the entire MXene sheet.…”

Section: Preparations and Properties Of Mxenesmentioning

confidence: 99%

Hetero‐MXenes: Theory, Synthesis, and Emerging Applications

et al. 2021

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Since their discovery in 2011, MXenes (abbreviation for transition metal carbides, nitrides, and carbonitrides) have emerged as a rising star in the family of 2D materials owing to their unique properties. Although the primary research interest is still focused on pristine MXenes and their composites, much attention has in recent years been paid also to MXenes with diverse compositions. To this end, this work offers a comprehensive overview of the progress on compositional engineering of MXenes in terms of doping and substituting from theoretical predictions to experimental investigations. Synthesis and properties are briefly introduced for pristine MXenes and then reviewed for hetero‐MXenes. Theoretical calculations regarding the doping/substituting at M, X, and T sites in MXenes and the role of vacancies are summarized. After discussing the synthesis of hetero‐MXenes with metal/nonmetal (N, S, P) elements by in situ and ex situ strategies, the focus turns to their emerging applications in various fields such as energy storage, electrocatalysts, and sensors. Finally, challenges and prospects of hetero‐MXenes are addressed. It is anticipated that this review will be beneficial to bridge the gap between predictions and experiments as well as to guide the future design of hetero‐MXenes with high performance.

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Ambient oxidation of Ti₃C₂ MXene initialized by atomic defects

Abstract: The mechanism of Ti3C2-MXene ambient oxidation has been revealed by electron microscopy, disclosing the effects of defects and Ti-ion diffusion.

Cited by 182 publications

References 33 publications

Improving oxidation stability of 2D MXenes: synthesis, storage media, and conditions

Improving oxidation stability of 2D MXenes: synthesis, storage media, and conditions

pH, Nanosheet Concentration, and Antioxidant Affect the Oxidation of Ti₃C₂T_x and Ti₂CT_x MXene Dispersions

Hetero‐MXenes: Theory, Synthesis, and Emerging Applications

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Ambient oxidation of Ti3C2 MXene initialized by atomic defects

Abstract: The mechanism of Ti3C2-MXene ambient oxidation has been revealed by electron microscopy, disclosing the effects of defects and Ti-ion diffusion.

Cited by 182 publications

References 33 publications

Improving oxidation stability of 2D MXenes: synthesis, storage media, and conditions

Improving oxidation stability of 2D MXenes: synthesis, storage media, and conditions

pH, Nanosheet Concentration, and Antioxidant Affect the Oxidation of Ti3C2Tx and Ti2CTx MXene Dispersions

Hetero‐MXenes: Theory, Synthesis, and Emerging Applications

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Ambient oxidation of Ti₃C₂ MXene initialized by atomic defects

pH, Nanosheet Concentration, and Antioxidant Affect the Oxidation of Ti₃C₂T_x and Ti₂CT_x MXene Dispersions