Advanced science: shape and spirit change -- two dimensional and three dimensional assembly of mxene

wallpapers Nicaragua News 2020-09-06

mxene is a kind of metal carbide or nitride material with two-dimensional layered structure which comes from ternary layered ceramic material Mn 1AXN (M is transition metal element a is main group element X is C or N n is generally 1-3). During the etching process a large number of functional groups (- F - Oh - O etc.) on the surface of mxene give it good hydrophilicity mxene has excellent conductivity (6000-8000 s) Because of its excellent thermal conductivity adjustable b gap excellent mechanical strength it has broad application prospects in the fields of energy conversion storage electromagnetic shielding sensing environmental protection. However similar to other two-dimensional materials mxene has the tendency of disordered powder "face to face" stacking agglomeration in practical applications which greatly limits its performance. Building multi-dimensional mxene assemblies while regulating the microstructure of mxene nanosheets reflects the excellent performance of mxene in the nano scale to the macro level which is an important measure to exp the practical application of mxene.

Based on the concept of graphene oxide (go) interface assembly the research group of

Professor Yang Quanhong Associate Professor Tao Ying from school of chemical engineering of Tianjin University systematically summarized the research progress of constructing mxene assemblies based on the assembly strategy of developing new two-dimensional materials mxene. According to the dimensions microstructure of assemblies under different scales mxene assemblies were classified how to realize M In addition the assembly strategy of mxene the application of its assembly are prospected.

(1) the two-dimensional assembly of

mxene is prone to self-assembly into two-dimensional films due to the existence of interlaminar van der Waals force. Intercalation agent or barrier agent is introduced between mxene layers by liquid-phase assembly process which can effectively control the interlaminar spacing of mxene assembled films (as shown in Figure 1). This two-dimensional assembly of mxene inherits the original physical chemical properties of mxene to the greatest extent can also customize the optimal layer spacing for different application fields so as to improve the utilization efficiency of mxene nanosheets.

(2) two dimensional macro assembly with micro three-dimensional structure

although mxene has some inherent advantages in structure assembly it is difficult to directly construct three-dimensional macro assembly of mxene due to its relatively small size poor flexibility strong hydrophilicity easy oxidation. Some mxene based two-dimensional macro assemblies with micro three-dimensional structure were first developed they can also be obtained by further modification of two-dimensional films. Compared with the two-dimensional assembly of mxene the three-dimensional porous structure at the micro level can more directly overcome the stacking problem caused by van der Waals force hydrogen bonding force expose more active sites improve the effective specific surface area which is better in the fields of energy storage electromagnetic shielding environmental protection.

(3) three dimensional macro assemblies

usually have three-dimensional porous network hierarchical structure which play an important role in the field of electrochemical energy storage for the construction of efficient reasonable three-dimensional conductive network ion transport channel. Unlike GO MXene is small rigid it is difficult to directly assemble in liquid phase to achieve three-dimensional gelation. However functional groups such as -OH -O on its surface still give it gelation possibility. At present cross-linking template methods are effective methods to construct three-dimensional macro assemblies in which cross-linking agent can balance the hydrophilicity of mxene by introducing appropriate driving force so as to promote phase separation form three-dimensional macro assemblies; template method can accurately control the pore shape pore size of three-dimensional macro assemblies realize the controllable construction of three-dimensional macro assemblies. Mxspe not only has many excellent properties such as light surface strength hydrophobicity so on. In this paper the applications of mxene assemblies in energy conversion storage electromagnetic shielding sensing environmental protection are reviewed the relationship between the structure performance of the assemblies is discussed.

The author of

summarizes the research progress related applications of mxene from the perspective of assembly discusses the challenges of constructing two-dimensional three-dimensional assembly of mxene prospects its assembly strategies applications which will help to solve the application bottleneck of mxene provide practical strategies for developing function oriented mxene materials promote the application of mxene materials in many fields especially in energy conversion It is of great significance to the development of the related fields of virtualization storage.

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