Search

Conductive fibers are needed for the development of flexible electronic and biomedical devices. MXene fibers show great promise for use in such applications because of their high conductivity. Current literature on MXene fiber development highlights the need for improving their mechanical properties and investigation of biocompatibility. Here the use of silk fibroin biopolymer as a MXene formulation additive for the production of MXene fibers is studied. It is found that the favorable silk fibroin–MXene interactions resulted in improved durability, withstanding up to 1 h of high frequency sonication in buffered solutions. Furthermore, fibers with ≈5 wt% silk fibroin displays interesting properties including high conductivity (≈3700 S cm−1), high volumetric capacitance (≈910 F cm−3), and non‐cytotoxicity toward THP‐1 monocytic cells. The results presented here provide an important insight into potential use of MXene fibers in flexible electronics and biomedical applications. [ABSTRACT FROM AUTHOR]

The outstanding electrical conductivity and high specific capacitance of 2D Ti3C2Tx MXene have made them promising materials for a wide range of applications including wearable electronics, energy storage, sensors, and electromagnetic interference shielding. However, the fabrication of MXene architectures, both pure and composite, often results in a trade‐off in properties. Here, it is reported that sequential bridging of MXene sheets significantly enhances the mechanical properties of its free‐standing films, with improvements in strength and toughness of up to ≈339 MPa and ≈12.0 MJ m−3, respectively, while simultaneously retaining both high conductivity (≈4850 S cm−1) and volumetric capacitance (≈1220 F cm−3). This sequential bridging strategy permits surface modification of MXene sheets while still yielding stable colloidal dispersions so that the subsequent MXene films comprise of aligned, evenly‐spaced, and interconnected sheets, which are critical for the development of robust energy storage devices and other high performance applications. [ABSTRACT FROM AUTHOR]

Textile devices have benefited from the discovery of new conductive materials and innovations in textile device design. These devices include textile‐based supercapacitors (TSCs), encompassing fiber, yarn, and fabric supercapacitors, which have demonstrated practical value in powering wearable devices. Recent review articles have highlighted the limited energy density of TSCs as an important challenge, demanding new electrode materials with higher electronic conductivity and theoretical capacitance than present materials. Ti3C2Tx, a member of the MXene family, is known for its metallic conductivity and high volumetric capacitance in acidic electrolytes due to its pseudocapacitive behavior. Driven by these excellent properties, recent literature has reported promising integration methods of Ti3C2Tx into TSCs with significantly improved areal and volumetric capacitance compared with non‐MXene‐based TSCs. Furthermore, knitted MXene‐based TSCs demonstrated practical application of wearable energy storage devices in textiles. Herein, the techniques used to produce MXene‐based fibers, yarns, and fabrics and the progress in architecture design and performance metrics are highlighted. Challenges regarding the introduction of this new material into fiber/yarn/fabric architectures are discussed, which will inform the development of textile‐based devices beyond energy storage applications. Opportunities surrounding the development of MXene‐based fibers with tunable mechanical, electrical, and electrochemical properties are proposed, which will be the direction of future research efforts. [ABSTRACT FROM AUTHOR]

The integration of nanomaterials with high conductivity into stretchable polymer fibers can achieve novel functionalities such as sensing physical deformations. With a metallic conductivity that exceeds other solution‐processed nanomaterials, 2D titanium carbide MXene is an attractive material to produce conducting and stretchable fibers. Here, a scalable wet‐spinning technique is used to produce Ti3C2Tx MXene/polyurethane (PU) composite fibers that show both conductivity and high stretchability. The conductivity at a very low percolation threshold of ≈1 wt% is demonstrated, which is lower than the previously reported values for MXene‐based polymer composites. When used as a strain sensor, the MXene/PU composite fibers show a high gauge factor of ≈12900 (≈238 at 50% strain) and a large sensing strain of ≈152%. The cyclic strain sensing performance is further improved by producing fibers with MXene/PU sheath and pure PU core using a coaxial wet‐spinning process. Using a commercial‐scale knitting machine, MXene/PU fibers are knitted into a one‐piece elbow sleeve, which can track various movements of the wearer's elbow. This study establishes fundamental insights into the behavior of MXene in elastomeric composites and presents strategies to achieve MXene‐based fibers and textiles with strain sensing properties suitable for applications in health, sports, and entertainment. [ABSTRACT FROM AUTHOR]

Textile‐based electronics enable the next generation of wearable devices, which have the potential to transform the architecture of consumer electronics. Highly conductive yarns that can be manufactured using industrial‐scale processing and be washed like everyday yarns are needed to fulfill the promise and rapid growth of the smart textile industry. By coating cellulose yarns with Ti3C2Tx MXene, highly conductive and electroactive yarns are produced, which can be knitted into textiles using an industrial knitting machine. It is shown that yarns with MXene loading of ≈77 wt% (≈2.2 mg cm−1) have conductivity of up to 440 S cm−1. After washing for 45 cycles at temperatures ranging from 30 to 80 °C, MXene‐coated cotton yarns exhibit a minimal increase in resistance while maintaining constant MXene loading. The MXene‐coated cotton yarn electrode offers a specific capacitance of 759.5 mF cm−1 at 2 mV s−1. A fully knitted textile‐based capacitive pressure sensor is also prepared, which offers high sensitivity (gauge factor of ≈6.02), wide sensing range of up to ≈20% compression, and excellent cycling stability (2000 cycles at ≈14% compression strain). This work provides new and practical insights toward the development of platform technology that can integrate MXene in cellulose‐based yarns for textile‐based devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hollow carbon spheres (MHCS) with controlled sheath thickness and nanochannels. • The MHCS separated 3D MXene/MHCS electrode by one-step filtration. • Nanochannels on the sphere sheath help the fast diffusion of ions in electrolyte. • Conductive sheath reduces the contact resistance between MXene sheets. The development of electrode materials with a hierarchically porous structure and good electrical connection is key to improving the charging-discharging rate and energy density of supercapacitors. However, the restacking issue of two-dimensional nanomaterials, such as MXene, seriously hinders the diffusion of electrolyte ions. Different from the extensively used sacrificing template method, a hierarchical heterostructure of electrically conducting mesoporous hollow carbon spheres (MHCS) and MXene composite electrode is designed and achieved through simple vacuum filtration without further template removing procedures. This direct preparation strategy not only effectively improves the specific surface area of the electrode but also enhances the abundant surface pores and good conductivity of MHCS, improving the penetration of the electrolyte solution and shortening the ion transport path, leading to a pronounced improvement in specific capacitance and rate performance of the electrodes. Additionally, the influence of sheath thickness of MHCSs on ion transfer rate is deeply discussed. The introduction of carbon nanotubes (CNTs) further improves conductivity and stability while maintaining good flexibility. Consequently, the MXene/MHCS/CNT film delivers a high specific capacitance (395F g−1 at 2 mV s−1), outstanding rate performance (70.9 % at 1000 mV s−1), and excellent cycling stability (98.3 % capacity retention after 10,000 cycles). Furthermore, the assembled symmetric supercapacitor provides a maximum energy density of 14.48 Wh kg−1. This work provides a quick and effective approach for constructing high performance 3D MXene architectures for fast ion transfer electrodes. [ABSTRACT FROM AUTHOR]

MXenes (two-dimensional early transition metal carbides and carbonitrides) possess both excellent conductivity and surface hydrophilicity, enabling more diverse potential applications. However, in flexible strain sensors, the flexible substrates are usually composed of hydrophobic elastomers such as thermoplastic polyurethane (TPU). To enhance the interactions between MXenes and hydrophobic. substrates, it is wiser to change the composition of the flexible substrate than to modify the surface of MXenes, so as to improve the interactions between the flexible substrate and MXenes without losing the excellent conductivity of MXene. We introduce polyacrylonitrile (PAN) into TPU, and then fabricate a flexible TPU/PAN mat through electrospinning. A highly conductive and stretchable Ti 3 C 2 MXene/TPU/PAN mat was then prepared by a simple dip-coating process. The interaction mechanism between Ti 3 C 2 MXene nanosheets and TPU/PAN mat was investigated by XPS and FT-IR. Finally, we build the MXene/TPU/PAN mat into a flexible strain sensor with excellent properties. By introducing PAN into flexible substrate, the interaction between Ti 3 C 2 MXene and the flexible substrate was effectively improved without compromising Ti 3 C 2 MXene's excellent conductivity. The MXene/TPU/PAN strain sensor possesses a wide sensing range (0–80%), a fast response (<140.6 ms), a low limit of detection (<0.1%), splendid coating adhesion and excellent durability (>1750 cycles). All of these properties are demanded in wearable electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • First report of MXene coated carbon fibre electrodes for structural supercapacitors. • Improved MXene adhesion through surface modification of carbon fibre. • Carbon fibre with NO 2 and NH 2 -terminal groups showed better adhesion to MXene. • 157 F/g−1 with MXene coated on poly(o-phenylenediamine) grafted carbon fibre. • Facile and scalable approach for sustainable energy storage composites. MXenes, while excellent for electrical energy storage, face challenges in translating their nanoscale properties to macroscale structures. To address this, MXene-coated carbon fibers (CF) were developed as electrode materials for structural supercapacitor composites. CF surface chemistry was tailored using aryl diazonium salts (–NO 2 , –NH 2 , -SH, –COOH) to optimize MXene adhesion. Electrodes were characterized for surface chemistry, morphology, and properties including electrochemical, mechanical, and interfacial aspects. Electrodes developed from MXene coated on CF functionalized with a poly(o -phenyelenediamine) coating exhibited a specific capacitance of 157 F/g−1 at 5 mV s−1, a ∼725-fold improvement in capacitance compared to pristine unfunctionalized CF, with minimal to no compromise in the underlying strength and stiffness of the CF. The MXene coating also improved the interfacial adhesion of the electrode to an epoxy-based resin by 54 %. The process was scaled up to functionalize and coat woven CF mats and were used to fabricate a structural supercapacitor device. The device exhibited a specific capacitance of 908 mF/g−1 at 0.5 mA g−1, representing a remarkable ∼42-fold improvement compared to the control. This lightweight multifunctional supercapacitor composite holds great potential in aerospace, automotive, and renewable energy storage sectors, addressing global challenges tied to fossil fuel combustion and associated environmental and socio-economic issues. [ABSTRACT FROM AUTHOR]