Latest ArticlesTwo-dimensional transition-metal carbide materials, or MXenes, have attracted great attention in energy-related fields due to their excellent electrical conductivity, and large interlayer spacing. In this work, a simple method involving combustion synthesis and acid treatment to prepare accordion-like Ti3C2Tx MXene with open structure and high crystallinity, which is employed as anode materials in lithium-ion capacitors. Due to the improved ion diffusion and electron transportation of Ti3C2Tx anode, the mismatched electrode kinetics can be largely alleviated to acquire an enhanced power performance. The assembled Ti3C2Tx-based lithium-ion capacitors provides a maximum energy density of 106 Wh/kg and still exhibits a superior energy density of 79 Wh/kg even at a higher power density of 5.2 kW/kg, which provides a new platform for MXene materials with porous and crystalline features toward both high energy and power densities.
Ti3C2 belongs to MXenes family, which is a new two-dimensional material and has been applied in many fields. With simple method of hydrothermal and high temperature calcination, nanostructured Ni/Ti3C2Tx hybrid was synthesized. The stable layer structure of Ti3C2 MXene providing high surface area as well as excellent electronic conductivity are beneficial for deposition and decomposition of discharge product Li2O2. Furthermore, possessing special catalytic activity, Ni nanoparticles with size of about 20 nm could accelerate Li2O2 breaking down. Taking advantage of two kinds of materials, Ni/Ti3C2Tx hybrid as cathode of Li-O2 battery can achieve a maximal specific capacity of 20, 264 mAh/g in 100 mA/g and 10, 699 mAh/g in 500 mA/g at the first cycle. This work confirms that the prepared Ni/Ti3C2Tx hybrid exhibiting better cycling stability points out a new guideline to improve the electrochemical performance of lithium-oxygen batteries.
Ti3C2Tx has been emerging as an attractive platform to prepare composite catalysts, and their assembly into integrated catalytic materials represents a key step forward toward practical applications. However, the swelling behavior of Ti3C2Tx leads to significant structure change, which challenges the stability of Ti3C2Tx-based integrated functional materials for catalytic applications. Here we report a facile synthesis of Pd/Ti3C2Tx⊂graphene hydrogels in which Pd/Ti3C2Tx are spatially encapsulated in the 3D porous graphene framework. The porous interconnected structure not only affords efficient mass transfer and desirable functional accessibility to catalytic active sites, but also effectively buffers the swelling behavior of Ti3C2Tx. When applied for catalytic hydrogenation of nitroaromatic compounds, the mechanically robust Pd/Ti3C2Tx⊂graphene hydrogels exhibit efficient activities, easy separability, and good cyclability. This work is expected to promote the application of Ti3C2Tx-based functional materials for practical applications involving interactions with salt solutions, such as supercapacitors, catalysis, and water purification.
The development of two-dimensional hybrid nanomaterial derived from MXenes as high performance electrode material is the key component for the advanced energy storage and conversion systems. In the past decades, MXene derived nanomaterials have attracted greatly interest in scientific activity and potential applications because of their unique synergistic properties such as high thermal stability, excellent electrical conductivity, large surface area, easy to handle and outstanding electro and photo chemical properties. This review is focused on the synthesis of hybrid nanomaterials from MXene (Ti3C2Tx) for renewable energy conversion and storage application including hydrogen evolution reaction, supercapacitor, lithium-ion batteries and photocatalysis. Finally, we also summarized the prospect and opportunities of novel two-dimensional hybrid nanomaterials derived MXene (Ti3C2Tx) for futuristic sustainable energy technology
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.
It 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.
Ti3CNTx MXenes with unique electrical conductivity can be widely applied for supercapacitors and electromagnetic shielding. However, its relatively low-yield quaternary nitrogen-containing Ti3AlCN ceramics precursor (less than 50%), due to the inevitable Al segregation during the synthesizing process, significantly hindered its widely commercial applications. Herein, we employed the controllable AlNoversaturation precursor strategy to precisely tune the phase transition point of quaternary Ti3AlCN ceramics to obtain high-yield Ti3AlCN precursor for the purpose of high conductivity Ti3CNTx MXenes. Combined energy dispersive X-ray spectrometer (XRD) with X-ray photoelectron spectroscopy (XPS) characterizations, the yield of the quaternary nitrogen-containing Ti3AlCN ceramics was evidently proved to be up to 70%, which is 1.4 times than that of previously reported works. Such relatively highyield quaternary Ti3AlCN is mainly ascribed to the elimination of Al segregation. Based on it, we further developed accordion-like two-dimensional (2D) MXene via hydrofluoric acid etch and vacuum freezedry. This novel accordion-like 2D Ti3CNTx MXene possesses high electrochemical capacitive properties (209 F/g). Therefore, this controllable AlN-oversaturation precursor strategy will pave a way to exploit costly high-yield MAX ceramics precursor for high conductivity MXenes and also play a powerful role in promoting their practical applications including electrical and magnetic engineering fields.
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.
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.