Latest ArticlesIt is essential to develop a methanol gas sensor with high selectivity and low working temperature for human health and environmental monitoring. In this work, a blend of PEDOT:PSS and Ti3C2Tx with the mass ratio of 4:1 is used to fabricate a methanol gas sensor. It possesses a high response ratio of the largest response and the second largest response (5.54) and an enhanced response compared to pure PEDOT:PSS and pure Ti3C2Tx tested at room temperature. These findings may pave the way towards design of the MXenes based high-performance gas-sensing materials in the future.
The rational design and construction of heterojunction structure is an effective strategy to improve the photocatalytic performance. Herein, a series of BiOBr nanosheets-immobilized TiO2/Ti3C2Tx MXene hybrid materials with heterojunction structure were synthesized by a facial one-step hydrothermal method. The ternary composites show outstanding performance as photocatalysts for the degradation of rhodamine B due to the optimized synergetic effects of BiOBr, TiO2 and Ti3C2Tx. The improved photocatalytic performance is remarkably attributed to the construction of a heterojunction between TiO2 and BiOBr due to their well-matching of energy band position, which can enhance the absorption for visible light and promote the transfer of photo-generated charge carriers. Moreover, Ti3C2Tx acts as an electron trap to further accelerate the separation of photo-generated electrons and holes.
The geometrically multiplied development of 2D MXenes has already promoted the prosperity of various fields of scientific researches especially but not limited in energy storage and conversion. Notably, cation intercalation can improve the interlayer spacing of MXenes resulting in tunable physical and chemical properties. Moreover, the synchrotron radiation X-ray characterizations have also shown high potential on exploring the property and structure of cation intercalated MXenes. This review is mainly focused on the recent achievements of cation intercalated MXenes through different methods on energy storage systems. Synchrotron-based X-ray absorption spectroscopic characterizations are emphasized to probe the local coordination and electronic structure in intercalated MXenes. The outlook of cation intercalation on MXenes and their applications are also discussed.
Ti3C2Tx, a most studied member of MXene family, shows promise as a candidate electrode for pseudocapacitor due to its electronic conductivity and hydrophilic surface. However, the unsatisfactory yield of Ti3C2Tx few-layer flakes significantly restricted it in real applications. Here, we proposed a simple solution to boost the yield of Ti3C2Tx few-layer flakes by decreasing precursor size. When using the small 500 mesh Ti3AlC2 powders as raw material, high yield of 65% was successfully achieved. Moreover, the asreceived small flakes also exhibit an enhanced pseudocapacior performance owing to their excellent electrical conductivity, expanded interlayer space and more O content on the surface. This work not only sheds light on the cost effective mass production of Ti3C2Tx few-layer flakes, but also provides an efficient solution for the design of MXene electrodes with high pseudocapacior performance.
Transition metal carbide, carbonitride and nitride MXenes, as the emerging two-dimensional (2D) nanomaterials, have aroused burgeoning research interest in a broad range of applications ranging from energy conversion to biomedicines attributing to their distinctive planar nanostructure, physiochemical properties and biological effects. They are featured with fascinating electronic, optical, magnetic, mechanical and thermal properties, which exert significant roles in biomedical applications of 2D MXenes. In this review, we briefly summarize the recent research progress of 2D MXenes and highlight their intrinsic chemistry in theranostic nanomedicines, focusing on the synthetic chemistry for MXenes construction, surface chemistry for surface engineering, physiochemical property for theranostic application and biological chemistry for biosafety evaluation. Furthermore, based on the current achievements on MXenes, their potential research direction, critical challenges and future development in biomedicine are also discussed. It is highly expected that 2D MXene-based nanosystems would have a broad application prospect in theranostic biomedicine provided the current facing critical issues and challenges are adequately solved.
The demand for flexible and freestanding electromagnetic interference (EMI) shielding materials are more and more urgent to combat with serious electromagnetic (EM) radiation pollution. Twodimensional Ti3C2Tx is considered as promising EMI shielding material to graphenes because of the low cost and high electrical conductivity. However, the shielding performance still needs to be optimized to decrease the reflection effectiveness (SER) and increase absorption effectiveness (SEA). Herein, we prepared Ti3C2Tx-bonded carbon black films with a porous structure. The SER decreased from 20 dB to 12 dB and the SEA increased from 31 dB to 47 dB. The best EMI shielding effectiveness can be as high as 60 dB with SEA of 15 dB and SER of 45 dB. Their calculated specific shielding effectiveness can be as high as 8718 dB cm2/g. These results indicate that the porous structure can enhance the absorption of the EMI shielding films, resulting from the enhanced scattering and reflection. Consequently, this work provides a promising MXene-based EMI shielding film with lightweight and flexibility.
Ti3C2Tx has shown great potential in energy storage filed, but the restacking between Ti3C2Tx nanosheets seriously hampers the maximization of its capacitance. In this study, we rationally designed and synthesized porous Ti3C2Tx assemblies without any additive by introducing ice as spacers using a facile freeze-drying method. The porous Ti3C2Tx assemblies have a three-dimensional network structure, which consists of ultra large Ti3C2Tx lamellar walls and lots of macro- and mesopores. It has been proven that there are more-O groups on the surface of the porous Ti3C2Tx assemblies than the Ti3C2Tx film. The porous Ti3C2Tx assemblies deliver a maximum areal capacitance of 1668 mF/cm2 when the mass loading is 8.4 mg/cm2, an optimized specific capacitance of 247.2 F/g when the mass loading is 5.3 mg/cm2, and 87% capacitance retention over 10000 cycles. The symmetric solid-state supercapacitors based on the porous Ti3C2Tx assemblies show an areal capacitance of 355.8 mF/cm2, the maximum power density of 50 mW/cm2 and an outstanding flexibility under different deformation.
The problem of water pollution has become increasingly serious, and it has already threatened the survival of mankind and has become an obstacle to the healthy development of human health. Here, we prepared a novel polyvinyl alcohol (PVA)/polyacrylic acid (PAA)/MXene fiber membrane by electrospinning. After heat treatment of film and subsequent modification with Pd nanoparticles, PVA/PAA/MXene@PdNPs composite nanofiber membrane with high specific surface area and excellent catalytic performance was finally prepared. The uniform distribution of MXene sheets in the composite fiber membrane not only solves the problem that the MXene sheet is not easy to be monolayerized, but also can grow the self-reduced Pd nanoparticles on the MXene sheets. In addition, the composite nanofiber membrane exhibits excellent catalytic ability and cycle stability for 4-nitrophenol (4-NP) and 2-nitrophenol (2-NA), providing new strategy for the study of catalytic composite materials related to degradation of wastewater.
Two-dimensional (2D) Ti3C2Tx MXene is an attractive additive not only used in base oil due to its low friction coefficient, but also used in composites due to its high aspect ratio and rich surface functional groups. So far there has been intense research into polymer matrix composites reinforced with Ti3C2Tx. Here we report on the use of 2D Ti3C2Tx to enhance the mechanical and frictional properties of Al matrix composites. Ti3C2Tx/Al composites were designed and prepared by pressureless sintering followed by hot extrusion technique. The prepared composites exhibit a homogeneous distribution of Ti3C2Tx. The Vickers hardness and the tensile strength continuously increase with increasing Ti3C2Tx content. A hardness of 0.52 GPa and a tensile strength of 148 MPa were achieved in the 3 wt% Ti3C2Tx/Al composite. The frictional properties of pure Al and the Ti3C2Tx/Al composite were comparably studied under dry sliding. A low friction coefficient of 0.2, twice lower than that of pure Al, was achieved in the 3 wt% Ti3C2Tx/Al composite. Ti3C2Tx acting as a solid lubricant reduces the abrasive wear in the composite, improving the frictional properties of Al matrix composites.
Combining high conductivity, hydrophilicity and excellent electrochemical performance in one, MXenes have attracted increasing attention since their inception. However, easy to stack caused by the van der Waals' force between the layers limits their practical application. Fortunately, intercalating other substances between layers of MXenes and getting intercalated MXene-based layered composites (IMLCs) with open structure can improve their physical and chemical properties effectively. Larger available surface helps expose more active sites and enlarged layer spacing facilitates ion transport. In addition, other substances fixed in the interlayers by MXenes' two-dimensional confinement effect can produce synergistic effect and expand their applicable range greatly. This review is dedicated to summarizing the preparation methods and applications of IMLCs, emphasizing the advantages of them in the fields of energy storage, catalysis, sensors, electromagnetic interference (EMI) shielding and biomedicine. Furthermore, prospects and further developments in these gratifying fields are also commented.
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