Highly Electrically Conductive Three-Dimensional Ti₃C₂T_x MXene/Reduced Graphene Oxide Hybrid Aerogels with Excellent Electromagnetic Interference Shielding Performances

Abstract

Two-dimensional transition-metal carbides/carbonitrides (MXenes) with both superb electrical conductivity and hydrophilicity are promising for fabricating multifunctional nanomaterials and nanocomposites. However, the construction of three-dimensional (3D) and lightweight MXene macroscopic assemblies with excellent electrical conductivity and mechanical performances has not been realized due to the weak gelation capability of MXene sheets. Herein, we demonstrate an efficient approach for constructing highly conductive 3D Ti3C2T x porous architectures by graphene oxide assisted hydrothermal assembly followed by directional freezing and freeze-drying. The resultant hybrid aerogels exhibit aligned cellular microstructure, in which the graphene sheets serve as the inner skeleton, while the compactly attached Ti3C2T x sheets present as shells of the cell walls. The porous and highly conductive architecture (up to 1085 S m–1) is highly efficient in endowing epoxy nanocomposite with a high electrical conductivity of 695.9 S m–1 and an outstanding electromagnetic interference (EMI)-shielding effectiveness of more than 50 dB in the X-band at a low Ti3C2T x content of 0.74 vol %, which are the best results for polymer nanocomposites with similar loadings of MXene so far. The successful assembly methodology of 3D and porous architectures of Ti3C2T x would greatly widen the practical applications of MXenes in the fields of EMI shielding, supercapacitors, and sensors.

Self‐Assembly of MXene‐Surfactants at Liquid–Liquid Interfaces: From Structured Liquids to 3D Aerogels

“…Then anocomposite with 0.40 vol% of Ti 3 C 2 T x exhibits as uperb average EMI shielding performance of 34.5 dB over the whole X-band, which is sufficient for many civil and military applications.T he results of SE divided by sample thickness (SE/d)a re summarized in Figure S11 and Table S1 to eliminate the effect of specimen thickness.I ti sw orth noting that the as-prepared Ti 3 C 2 T x @epoxy nanocomposite shows ac ompetitive shielding performance of 17.3 dB mm À1 in comparison to other shielding materials. [32] In summary,wehave demonstrated the interfacial activity of MXSs formed by the interactions between Ti 3 C 2 T x and POSS-NH 2 at the oil-water interface.MXSs rapidly form and assemble at the interface with acontrollable packing density, and when jammed, produce as olid-like assembly with excellent mechanical properties.T aking advantage of MXSs, 2D films,a nd structured Pickering emulsions can be easily prepared. Furthermore,b yfreeze-drying the concentrated emulsion droplets,l ightweight, hydrophobic 3D MXene aerogels are produced from the bottom up,w hich can be used for oil adsorption and EMI shielding.T his intriguing assembly strategy at the liquid-liquid interface provides as imple route to construct MXene assemblies from the mesoscale to macroscale,h aving significant practical importance.…”

“…As agraphene-like 2D material, the distinctive properties of MXenes,e specially the high hydrophilicity and metallic conductivity,m ake them attractive for many applications,s uch as energy storage,s ensors,c atalysis,n anocomposites,a nd electromagnetic interference (EMI) shielding. [18,19] Up to now,a pplications of MXenes as building blocks,functional assemblies including one-dimensional (1D) fibers, [20][21][22] 2D films, [23][24][25][26][27] and 3D monoliths [28][29][30][31][32] have been reported through av ariety of assembly strategies.H owever,[*] Prof.…”

“…As agraphene-like 2D material, the distinctive properties of MXenes,e specially the high hydrophilicity and metallic conductivity,m ake them attractive for many applications,s uch as energy storage,s ensors,c atalysis,n anocomposites,a nd electromagnetic interference (EMI) shielding. [18,19] Up to now,a pplications of MXenes as building blocks,functional assemblies including one-dimensional (1D) fibers, [20][21][22] 2D films, [23][24][25][26][27] and 3D monoliths [28][29][30][31][32] have been reported through av ariety of assembly strategies.H owever, despite such progress,l ittle attention has been paid to the interfacial properties of MXenes between two immiscible liquids (e.g.,oil and water), and the construction of functional assemblies by the interfacial self-assembly of MXenes is still limited. Thei nherent negative charge of the oil-water interface is the primary reason underpinning this.P ristine MXenes are negatively charged and strongly hydrophilic and, as such will not segregate to the interface,b ut remain dispersed in the aqueous phase.V ery recently,bythe electrostatic adsorption of cationic cetyltrimethylammonium bromide (CTAB) onto the MXene surface,H uang and coworkers reported that the hydrophilic-hydrophobic balance of MXene could be tuned, and stable Pickering emulsions could be prepared.…”

MXene-based 3D porous macrostructures for electrochemical energy storage

“…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.…”

“…One of the first studies of unidirectional freeze-casting of MXenes was reported by Zhao et al to produce a GO-assisted assembled MXene aerogel [61]. Based on the porous architecture, they propose an assembly mechanism as follows: due to their affinity, a stable aqueous Ti 3 C 2 T x /GO suspension is formed.…”