3D Macroscopic Architectures from Self‐Assembled MXene Hydrogels

Shang, Tongxin; Lin, Zifeng; Qi, Changsheng; Liu, Xiaochen; Li, Pei; Tao, Ying; Wu, Zhitan; Li, Dewang; Simon, Patrice; Yang, Quan‐Hong

doi:10.1002/adfm.201903960

Cited by 408 publications

(320 citation statements)

References 48 publications

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“…Yang et al synthesized a 3D MXene hydrogel by a facile self-assembly method in the presence of GO and ethylenediamine (EDA) ( Figure 5G). 75 During the gelation, GO acts as a crosslinking agent and EDA acts as an initiator for inducing MXene flakes to form the hydrogel with unique 3D porous structure ( Figure 5H). When used as an electrode for supercapacitors, 3D MXene hydrogel exhibits superb gravimetric capacitance and excellent rate performance ( Figure 5I).…”

Section: Nanosheet-assembled Hierarchical Structuresmentioning

confidence: 99%

Interfacial structure design of MXene‐based nanomaterials for electrochemical energy storage and conversion

Luo

Matios

Wang

et al. 2020

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167

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2D transition metal carbides, carbonitrides, and nitrides known as MXenes possess high electrical conductivity, large redox active surface area, rich surface chemistry, and tunable structures. Benefiting from these exceptional chemical and physical properties, the applications of MXenes for electrochemical energy storage and conversion have attracted increasing research interests around the world. Notably, the electrochemical performances of MXenes are directly dependent on their synthesis conditions, interfacial chemistries and structural configurations. In this review, we summarize the synthesis techniques of MXenes, as well as the recent advances in the interfacial structure design of MXene‐based nanomaterials for electrochemical energy storage and conversion applications. Additionally, we provide an in‐depth discussion on the relationship between interfacial structure and electrochemical performance from the perspectives of energy storage and electrocatalysis mechanisms. Finally, the challenges and insights for the future research of interfacial structure design of MXenes are outlined.

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Section: Nanosheet-assembled Hierarchical Structuresmentioning

confidence: 99%

Interfacial structure design of MXene‐based nanomaterials for electrochemical energy storage and conversion

Luo

Matios

Wang

et al. 2020

InfoMat

167

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“…Different from the above 2D materials, MXenes prepared by selective etching contain a number of functional groups on their surfaces and edges (F − , O, and OH) show good dispersion in aqueous solution and have the potential to build 3D MXene‐based assemblies by solution‐based techniques. With the GO as the linker, 3D graphene/MXene hybrid monoliths have been assembled in solution with a low temperature heating . In the assembly processes, the laminated MXene domains interacted with the π‐conjugated GO sheets which then guided the formation of the 3D structure.…”

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confidence: 99%

Fast Gelation of Ti₃C₂T_x MXene Initiated by Metal Ions

et al. 2019

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Graphene faces the same problem, but its self-assembly into a 3D structures can effectively solve these problems. [5,6] The gelation of graphene oxide (GO) is the mostly used method to prepare a 3D assembled structure, and this process is triggered by the surface chemistry changes of GO NSs in solution. However, the gelation of the other 2D materials, such as transition metal dichalcogenides (TMDs), transition metal oxides (TMOs), and h-BN, [7][8][9][10] is difficult to achieve because of the fewer functional groups on their surface and their poor dispersion in an aqueous solution.Different from the above 2D materials, MXenes prepared by selective etching contain a number of functional groups on their surfaces and edges (F − , O, and OH) [11] show good dispersion in aqueous solution and have the potential to build 3D MXene-based assemblies by solution-based techniques. With the GO as the linker, 3D graphene/MXene hybrid monoliths have been assembled in solution with a low temperature heating. [12,13] In the assembly processes, the laminated MXene domains interacted with the π-conjugated GO sheets which then guided the formation of the 3D structure. The use of surfactants or polymers as the linkers to realize side-by-side joining of MXene NSs also has the potential to build 3D MXene-based monoliths. [14][15][16] However, all these strategies involve a complex process in which the MXenes are easily oxidized due to their high chemical activity. In addition, the above assembly process is different from the GO assembly that relies on self-gelation and has many advantages for achieving structure control by simply changing the solvent or the drying process. [17,18] Until now, the gelation of MXene in a similar manner to that of GO has been difficult to realize.Here, we report the fast gelation of MXene in an aqueous solution initiated by divalent metal ions. In a typical process, Fe 2+ ions are introduced in the MXene solution to destroy the electrostatic repulsive forces between the NSs and link them together, forming a stable 3D MXene hydrogel, similar to the GO hydrogel and its gelation process. [19] The use of metal ions as the joining sites enhances the interlinking of MXene NSs to form a 3D network due to their strong binding energy with the OH groups on the MXene surface. As a result, the formed hydrogel effectively suppresses the restacking of MXene NSs Gelation is an effective way to realize the self-assembly of nanomaterials into different macrostructures, and in a typical use, the gelation of graphene oxide (GO) produces various graphene-based carbon materials with different applications. However, the gelation of MXenes, another important type of 2D materials that have different surface chemistry from GO, is difficult to achieve. Here, the first gelation of MXenes in an aqueous dispersion that is initiated by divalent metal ions is reported, where the strong interaction between these ions and OH groups on the MXene surface plays a key role. Typically, Fe 2+ ions are introduced in the MXene dispersion whic...

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“…Some works report the formation of hybrid graphene/MXene composites [59][60][61][62][63]. GO can help to stabilize the MXene flakes in the suspension forming a composite sol or gel, making it possible to freeze-dry it.…”

Section: Assembly By Induced Gelationmentioning

confidence: 99%

MXene-based 3D porous macrostructures for electrochemical energy storage

et al. 2020

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2D transition metal carbides and nitrides (MXenes) have shown outstanding potential as electrode materials for energy storage applications due to a combination of metallic conductivity, wide interlayer spacing, and redox-active, metal oxide-like surfaces capable of exhibiting pseudocapacitive behavior. It is well known that 2D materials have a strong tendency to restack and aggregate, due to their strong van der Waals interactions, reducing their surface availability and inhibiting electrochemical performance. In order to overcome these problems, work has been done to assemble 2D materials into 3D porous macrostructures. Structuring 2D materials in 3D can prevent agglomeration, increase specific surface area and improve ion diffusion, whilst also adding chemical and mechanical stability. Although still in its infancy, a number of papers already show the potential of 3D MXene architectures for energy storage, but the impact of the processing parameters on the microstructure of the materials, and the influence this has on electrochemical properties is still yet to be fully quantified. In some situations the reproducibility of works is hindered by an oversight of parameters which can, directly or indirectly, influence the final architecture and its properties. This review compiles publications from 2011 up to 2020 about the research developments in 3D porous macrostructures using MXenes as building blocks, and assesses their application as battery and supercapacitor electrodes. Recommendations are also made for future works to achieve a better understanding and progress in the field. carbon and/or nitrogen and T x represents surface terminations which vary depending on the synthesis method used (for example, hydroxyl, oxygen, or fluorine) [10].With less than 10 years since their discovery, efforts are still mainly pointed towards the assessment of its potentialities and exploration of its properties, while their integration and application in various engineering fields are still very much in their infancy. Nevertheless, investigations have shown very competitive results in energy storage devices attracting a lot of interest in the field. In particular, the inner conductive metal carbide layers provide fast electron supply to electrochemically active sites, and functional groups on the surface, allow water intercalation and fast redox activity for pseudocapacitive energy storage [11][12][13]. Besides energy storage, MXenes also showed promising properties and have been researched for a variety of other areas, such as electromagnetic shielding, environmental, sensors, optoeletronic devices, and renewable energy [9,[14][15][16].For most practical applications, the MXene powders must be assembled or processed into a macroscopic sample such as, for example, an electrode. Conventionally this is done either by mixing it with a solvent to form a slurry which is painted over a substrate, by directly vacuum filtration, by spin coating, or by spraying the MXene suspension to form a compact film. During these processes, there i...

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3D Macroscopic Architectures from Self‐Assembled MXene Hydrogels

Cited by 408 publications

References 48 publications

Interfacial structure design of MXene‐based nanomaterials for electrochemical energy storage and conversion

Interfacial structure design of MXene‐based nanomaterials for electrochemical energy storage and conversion

Fast Gelation of Ti₃C₂T_x MXene Initiated by Metal Ions

MXene-based 3D porous macrostructures for electrochemical energy storage

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3D Macroscopic Architectures from Self‐Assembled MXene Hydrogels

Cited by 408 publications

References 48 publications

Interfacial structure design of MXene‐based nanomaterials for electrochemical energy storage and conversion

Interfacial structure design of MXene‐based nanomaterials for electrochemical energy storage and conversion

Fast Gelation of Ti3C2Tx MXene Initiated by Metal Ions

MXene-based 3D porous macrostructures for electrochemical energy storage

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Fast Gelation of Ti₃C₂T_x MXene Initiated by Metal Ions