News

Yonsei University recently published a research article "Sensing with MXenes:" in the internationally renowned journal Advanced Materials. Progress and Prospects ", MXene's two-dimensional structure facilitates functionalization with various end groups, providing a large number of surface active sites. These parts can serve as highly sensitive sensory platforms for various external stimuli. In addition, the high conductivity of the MXenes is ideal for achieving low noise sensory responses. Thus, these properties suggest that MXenes is a very promising alternative sensor material that enables high sensitivity, extremely low detection limits (LOD) and minimum detectable quantities in a variety of sensor applications. Finally, the water dispersion of MXenes is conducive to environmentally friendly preparation and modification treatment; Therefore, they are more advantageous in terms of processing. This paper is divided into three parts, the first part: MXene introduction and sensor development; The second part: synthesis and properties of MXene; Part III: MXene Sensing applications (3.1 Chemical sensors; 3.2 Biosensor; 3.3 Physical Sensors).

MXene is considered by many research fields to be a revolutionary 2D material. Especially in the field of sensors, the high electrical conductivity and large surface area of MXENes-like metals are ideal properties as an alternative sensor material that can transcend the boundaries of existing sensor technology. This objective review provides a comprehensive overview of the latest advances in MXene-based sensor technology, as well as a roadmap for the commercialization of MXene-based sensors. The existing sensors are systematically divided into chemical sensors, biological sensors and physical sensors. Each category is divided into different subcategories according to the four basic working mechanisms of the sensor, namely, electrical, electrochemical, structural or optical sensing mechanisms. Representative structural and electrical methods are presented to improve performance in each category. Finally, the factors that hinder the commercialization of MXene sensors are discussed, and several breakthroughs are proposed to realize the commercialization of MXene sensors. This review provides broad insights on previous and existing MXene-based sensor technologies, as well as a vision for the future generation of low-cost, high-performance, and multimodal sensors for software electronics applications.

Studies have shown that single-layer Ti3C2Tx nanosheets have a light transmittance of about 97% in the visible region, and have metal conductivity and hydrophilicity, and can be stably dispersed in the water medium. Therefore, researchers have used single-layer Ti3C2Tx nanosheets to prepare transparent conductive materials, and have made a breakthrough. On February 7, 2023, ACS Nano reported that researchers developed a MXene dispersion solution with a high monolayer ratio, large size and narrow particle size distribution through the three-step method of etching, stripping and gradient centrifugation. The average size of Ti3C2Tx nanosheets is 12.2μm, and the maximum size can reach 30μm. The dispersion liquid contains almost no Ti3C2Tx fragments with the transverse size of nanometer. The researchers then prepared a transparent conductive electrode (TCE) with a highly dense microstructure by inducing the orientation of the nanosheets by shear force, which has good mechanical bending properties. In addition, the number of grain boundaries between the nanosheets is significantly reduced in the film assembled from the large-size nanosheets compared to the small-size nanosheets. Therefore, at a given thickness, the former has a higher conductivity, and its maximum TCE conductivity can reach ~20000 S/cm, while there is no obvious seepage problem at high light transmittance. On the same day, Advanced Functional Materials reported that by continuously optimizing the particle size distribution of MXene and the adaptation parameters of the slit coating, the researchers developed a large area uniform highly conductive film at room temperature, with extremely low surface roughness, which showed a significant mirror effect from a macro perspective. By adjusting the processing conditions, ink concentration and substrate type of slit coating, various transparent conductive films with excellent photoelectric properties can be obtained. At T=93%, the nanosheets can still be closely connected with each other, and the compact stack is arranged on the substrate to form a continuous conductive path, avoiding the seepage phenomenon under high light transmittance, achieving an average conductivity of 13 000 S/cm, and having a strong adhesion on the PET and glass substrate. On March 6, 2023, Nano Energy reported that researchers have integrated the Ti3C2Tx/ZnO structure into a flexible photodetector with integrated properties, including transparency and energy efficiency, with a transparent photodetector (TPDs) on an ITO/PET substrate with a visible light transmittance of up to 68%. Density functional theory calculations suggest Ti3C2Tx function layer has better charge transport channel, so as to improve the Ti3C2Tx/Al2O3 / ZnO/Ti3C2Tx/ITO/PET thermal photoelectric current detector, makes the TPDs response rate is 0.34 W - 1 A, The detection rate is 1.4 × 10 13Jones. Based on the ultra-fast optical response characteristics of TPDs (8 μs), it can effectively convert the Moss code in the encrypted optical signal into text information. We are looking forward to whether the single-layer Ti3C2Tx dispersion will glow and heat up in the field of transparent conductive films like graphene, carbon nanotubes and metal nanowires in the future.

Non-metallic catalysts mainly include carbon-based catalysts and some boron and phosphorus based catalysts. Typically, carbon-based catalysts have a porous structure and large surface area, which facilitates the exposure of more active sites and provides a rich channel for proton and electron transport. Various oxygen-containing functional groups and some defects on the surface and edge of graphene oxide make it have different electrical properties and catalytic activities. Researchers use various chemical modifications and chemical bonding methods to modify other beneficial components on the surface functional groups of GO to prepare a new type of electrocatalyst. Using graphithinyne as a substrate, the researchers found that single boron and nitrogen atoms doping can reduce CO2 to ethylene. Fewer layers of black phosphorus nanosheets have better activity and selectivity to NRR because of more active sites and weaker HER. Among the above three types of electrocatalysts, two-dimensional ultra-thin nanosheet structural materials are widely used in the field of catalysis. The characteristics of high specific surface area, a large number of exposed active sites, and non-stacked structure make them have natural catalytic advantages. Two-dimensional single-atom catalysts based on two-dimensional materials have also become a research hotspot in electrocatalysis.

Transition metal catalysts include transition metal hydroxides, oxides, sulfides, phosphates, and alloys. Molybdenum is a transition metal for NRR, and several molecular complexes based on molybdenum have been developed for electrocatalytic ammonia synthesis, such as molybdenum oxide, molybdenum nitride, molybdenum carbide and molybdenum sulfide, which can be used for NRR reactions, with MoS2 being the most widely studied. The edge of MoS2 is the active site of the electrocatalytic reaction and can be used to electrocatalyze NRR. In addition, MXenes materials have good mechanical properties and large specific surface area, and their electrical conductivity and abundant active sites on the base surface play an important role in the development of electrocatalysis. MXene materials have been shown to be useful for electrocatalysis of HER/OER/ORR reactions. Transition metal catalysts include transition metal hydroxides, oxides, sulfides, phosphates, and alloys. Molybdenum is a transition metal for NRR, and several molecular complexes based on molybdenum have been developed for electrocatalytic ammonia synthesis, such as molybdenum oxide, molybdenum nitride, molybdenum carbide and molybdenum sulfide, which can be used for NRR reactions, with MoS2 being the most widely studied. The edge of MoS2 is the active site of the electrocatalytic reaction and can be used to electrocatalyze NRR. In addition, MXenes materials have good mechanical properties and large specific surface area, and their electrical conductivity and abundant active sites on the base surface play an important role in the development of electrocatalysis. MXene materials have been shown to be useful for electrocatalysis of HER/OER/ORR reactions.

Carbon nanotubes, as one of the most representative materials in carbon nanomaterials, have been intensively studied for more than 30 years, and countless results have been achieved, and a number of excellent works have emerged in the top journal of 2023. On January 26, 2023, Nature Energy reported the application of CNT yarns in mechanical energy collectors. The device uses stretching to make the capacitance of the capacitor change, causing a current in the circuit, which converts mechanical energy into electrical energy. The researchers prepared the twisted yarn of CNT by modifying the twisting mode of conical rotation to twisting mode. This mechanical energy collector based on CNT yarns has improved its energy conversion efficiency from 7.6% to 17.4% (stretching) and 22.4% (twisting). For mechanical energy harvesting between 2 and 120 Hz, this twisted pair wire has higher gravitational peak power and average power than non-twisted pair mechanical energy harvesters that have been reported. On February 9, 2023, Advanced Energy Materials reported that researchers have used a self-assembly strategy of covalent organic scaffold membranes to give the membranes (HB/CNT@COF) multiple functions (sodium ion transport, confinement, and polysulfide conversion) to maintain the stability of RT/Na-S battery systems. Due to the synergistic action of hydroxynaphthol blue (HB) and multi-walled carbon nanotubes (CNT), the HB/CNT@COF battery has a capacity of 733.4mAh g-1 with limited capacity attenuation after 400 cycles at 4 C, which is almost 4 times that of commercial glass fiber membranes. In addition to the above reports, Applied Catalysis B: Environmental reported the application of carbon nanotubes in oxygen catalysis, oxygen reduction catalysis in zinc-air batteries, and efficient electrochemical CO2 conversion in a number of consecutive articles in February, and carbon nanotubes have mushroomed in various top journals, which shows their position in the field of nanomaterials. How did the carbon nanotubes in the top issue of 2023 perform

MXenes(two-dimensional (2D) transition metal (TM) carbides (TMCs), TM nitride (TMNs) and TM Carbon nitride (TMCNs) are the largest family of two-dimensional materials (2DMs) in the future, with novel applications in different nanotechnology research at the academic and industrial levels. MXenes nanomaterials have the potential to be classified as "wonder materials" for two-dimensional nanomaterials (NMs). Since its first discovery in 2011, MXenes have been studied and synthesized for more than a decade, with more than 50 members conducting experimental studies and more than 100 members conducting theoretical studies to date. The synthesis technology is not limited to the top-down HF-based etching method introduced for the first time, but new innovative synthesis methods such as anhydrous etching, molten salt etching and bottom-up chemical vapor deposition (CVD) method are also investigated, providing a multifunctional surface chemistry MXenes NMs with novel structure and desirable properties. Because of its unique layered structure, excellent electrochemical performance and excellent functional performance, MXenes is widely used in flexible energy storage devices such as secondary batteries, supercapacitors, microbatteries and microbatteries. In this review, we will first discuss in detail the synthetic methods of MXenes NMs, and secondly the properties of the selections, as well as their application in various fesd. After that, we will summarize and discuss current issues related to the synthesis of MXenes NMs and its application in fesd, as well as possible solutions. Finally, we will discuss the future progress of Mxenes-based NMSS in wearables and fesd, their limitations and recommendations.

Source Title: Researchers for the first time from the atomic scale reduction of MXenes oxidation kinetics Recently, the team of Associate Professor Meng Xing, Key Laboratory of New Battery Physics and Technology of the Ministry of Education, College of Physics, Jilin University, has made important progress in the theoretical calculation of the oxidation behavior of two-dimensional transition metal carbides/nitrides/carbon nitrides (MXenes), and the relevant results were published online in the German Applied Chemistry on June 14, 2023. Because of its high conductivity and rich surface functional groups, MXenes is widely used in energy, electronic devices, biomedicine and other fields. However, MXenes easily degrades into transition metal oxides in wet environments or aqueous solutions, which limits its application in various fields. Therefore, how to synthesize MXenes materials with high chemical stability is a key scientific problem to be solved urgently. In the study, Meng's research team conducted an in-depth theoretical calculation study on the oxidation behavior of the super-large Mxenes-water system. By combining machine learning with first-principles calculations, the researchers achieved nanosecond molecular dynamics simulations with DFT accuracy, and for the first time reduced the kinetic process of MXenes oxidation from the atomic scale, revealing the nature of the exponential decay of MXenes oxidation rate observed experimentally. The oxidation mechanism of MXenes in wet environment or aqueous solution was elucidated. The researchers developed A neural network potential function for the MXENes-water system, which performs well on the test set, with root-mean-square errors of 2.35meV/atom for energy and 0.083eV/ A for force compared to DFT calculations. The MD simulation based on the potential function is highly consistent with the AIMD simulation in the radial distribution function and the dynamic density property test. The MD simulation results of MXENes-water system show that the thicker the water layer, the more vertical hydrogen bonds per unit of water molecules, the more limited the movement of water molecules to the MXenes base surface, resulting in an increase in the average distance between the transition metal atoms and the oxygen atoms in water, and the MXenes oxidation rate decreases with the increase of the water layer thickness. At the same time, the oxidation of MXenes will release free protons, which will form a typical hydrated proton with water, thus binding the movement of water molecules, making the oxidation rate of MXenes decrease with the increase of time. The average distance between different types of transition metal atoms and oxygen atoms in water, as well as the probability of physical adsorption of water molecules on the MXenes base surface, demonstrate the existence of an oxide protective layer on the MXenes surface. These important findings provide theoretical guidance for the synthesis of highly stable MXenes materials.

[English name] : Vanadium Aluminium Carbide [CAS] : 12179-42-9 Product Code: 23-2-13-1-6-1 [Product description] : Vanadium carbide aluminum ceramic powder through high temperature plasma sintering V, Al, C powder mixture, after mechanical crushing and inert gas Bulk grinding preparation. [Packaging specifications] : Fixed packaging 5/10/50/100/500g, or according to customer needs; [ Intended use ] : For the preparation of MXenes by chemical etching, which is required for experimental research in physical chemistry; [ Basic Information ] : 1. Chemical formula: V2AlC 2. Component elements: V, Al, C 3. Relative molecular weight: 140.8645 4. Chemical state: micro-nano size particles 5. Appearance and properties: dark brown particles of micro and nano size [ Product performance index ] : 1. Crystal structure: hexagonal, P63/mmc [194] 2. Cell parameters: a= 2.913A, b= 2.913A, c= 13.14A; α=90, β=90, γ=120; 3. PDF No.:29-0101 (refer to the International Diffraction Data Center PDF-2004 database); 4. Density: 3.99(g/cm 3); 5. Boiling point: 6. Melting point: 7. Flash point: meaninglessness; 8. Purity: --; [ Storage Conditions and expiry date ] This product should be stored at room temperature in a dry place away from light, to avoid contact with acids, alkalis and other liquids, long-term storage will occur slow oxidation. [ Test method ] Crystal results can be confirmed by X-ray powder diffractometer. Confirmation of element composition by energy dispersive X-ray detector; The morphology of particles was characterized by the same morphology characterization. The particle size distribution was evaluated by laser particle size analyzer. [ Safety Protection ] 1. Health hazards Hazard category: Non-hazardous chemicals Chemical category: ceramic powder; Invasion route: inhalation, ingestion; Health hazards: dust irritates the eyes, oral irritation of the gastrointestinal tract; 2. First aid measures Skin contact: Take off the contaminated clothing and rinse the skin thoroughly with flowing water; Eye contact: Lift eyelids and rinse with plenty of running water or saline for at least 15 minutes; Inhalation: quickly leave the scene to the fresh air; Ingestion: Drink enough warm water, induce vomiting, medical treatment; 3. Ignition and explosion characteristics and fire protection Combustibility: non-flammable;

[English name] : Molybdenum Titanium Aluminium Carbon [CAS] : Product Code: 42-2-22-2-131-6-3 [Product description] : Molybdenum titanium aluminum carbon ceramic powder through high temperature plasma sintering Mo, Ti, Al, C powder mixture, after It was prepared by mechanical crushing and inert gas grinding. [Packaging specifications] : Fixed packaging 5/10/50/100/500g, or according to customer needs; [ Intended use ] : For the preparation of MXenes by chemical etching, which is required for experimental research in physical chemistry; [ Basic Information ] : 1. Chemical formula: Mo2Ti2AlC3 2. Component elements: Mo, Ti, Al, C 3. Relative molecular weight: 350.64 4. Chemical state: micro-nano size particles 5. Appearance and properties: dark brown particles of micro and nano size [ Product performance index ] : 1. Crystal structure: hexagonal, P63/mmc [194] 2. Cell parameters: a= A, b= A, c= A; α=, β=, γ=; 3. PDF No.: (refer to the International Diffraction Data Center PDF-2004 database); 4. Density: (g/cm 3); 5. Boiling point: 6. Melting point: 7. Flash point: meaninglessness; 8. Purity: --; [ Storage Conditions and expiry date ] This product should be stored at room temperature in a dry place away from light, avoid contact with acid, alkali and other liquids, long-term storage will slow Slow oxidation. [ Test method ] Crystal results can be confirmed by X-ray powder diffractometer. Carried out by an energy-dispersive X-ray detector Element composition confirmation; The morphology of particles was characterized by the same morphology characterization. The particle size distribution was evaluated by laser particle size analyzer. [ Safety Protection ] 1. Health hazards Hazard category: Non-hazardous chemicals Chemical category: ceramic powder; Invasion route: inhalation, ingestion; Health hazards: dust irritates the eyes, oral irritation of the gastrointestinal tract; 2. First aid measures Skin contact: Take off the contaminated clothing and rinse the skin thoroughly with flowing water; Eye contact: Lift eyelids and rinse with plenty of running water or saline for at least 15 minutes; Inhalation: quickly leave the scene to the fresh air; Ingestion: Drink enough warm water, induce vomiting, medical treatment; 3. Ignition and explosion characteristics and fire protection Combustibility: non-flammable;

[Name] : Hafnium Indium Carbide [CAS] : [Product Code] : 72-2-49-1-6 [Product description] : Indium hafnium carbide ceramic powder is sintered Hf, In, C powder mixture by high temperature plasma, and then processed by machinery Crushing and inert gas grinding preparation. [Packaging specifications] : Fixed packaging 5/10/50/100/500g, or according to customer needs; [ Intended use ] : For the preparation of MXenes by chemical etching, which is required for experimental research in physical chemistry; [ Basic Information ] : 1.Chemical formula: Hf2 InC 2. Component elements: Hf, In, C 3. Relative molecular weight: 483.798 4. Chemical state: micro-nano size particles 5. Appearance and properties: dark brown particles of micro and nano size [ Product performance index ] : 1. Crystal structure: hexagonal, P63/mmc [194] 2. Cell parameters: a= 3.308A, b= 3.308A, c= 14.706A; α=90, β=90, γ=120; 3. PDF No.:17-0437 (refer to the International Diffraction Data Center PDF-2004 database); 4. Density: 11.51 (g/cm 3); 5. Boiling point: 6. Melting point: 7. Flash point: meaninglessness; 8. Purity: --; [ Storage Conditions and expiry date ] This product should be stored at room temperature in a dry place away from light, avoid contact with acid, alkali and other liquids, long-term storage will slow Slow oxidation. [ Test method ] Crystal results can be confirmed by X-ray powder diffractometer. Carried out by an energy-dispersive X-ray detector Element composition confirmation; The morphology of particles was characterized by the same morphology characterization. The particle size distribution was evaluated by laser particle size analyzer. [ Safety Protection ] 1. Health hazards Hazard category: Non-hazardous chemicals Chemical category: ceramic powder; Invasion route: inhalation, ingestion; Health hazards: dust irritates the eyes, oral irritation of the gastrointestinal tract; 2. First aid measures Skin contact: Take off the contaminated clothing and rinse the skin thoroughly with flowing water; Eye contact: Lift eyelids and rinse with plenty of running water or saline for at least 15 minutes; Inhalation: quickly leave the scene to the fresh air; Ingestion: Drink enough warm water, induce vomiting, medical treatment; 3. Ignition and explosion characteristics and fire protection Combustibility: non-flammable;

[English name] : Chromium Aluminum Carbide [CAS] : 12179-41-8 Product Code: 24-2-13-1-6-1 [Product description] : Chromium carbide aluminum ceramic powder through high temperature plasma sintering Cr, Al, C powder mixture, after mechanical crushing and inert gas Bulk grinding preparation. [ Packaging specifications ] : Fixed packaging 5/10/25/50/100g, or according to customer needs; [ Intended use ] : For the preparation of MXenes by chemical etching, which is required for experimental research in physical chemistry; [ Basic Information ] : 1. Chemical formula: Cr2AlC 2. Component elements: Cr, Al, C 3. Relative molecular weight: 142.9737 4. Chemical state: micro-nano size particles 5. Appearance and properties: dark brown particles of micro and nano size [ Product performance index ] : 1. Crystal structure: hexagonal, P63/mmc [194] 2. Cell parameters: a= 2.85958A, b= 2.85958A, c= 12.81456A; α=90, β=90, γ=120; 3. PDF No.:29-0017 (refer to the International Diffraction Data Center PDF-2004 database); 4. Density: 3.9 (g/cm 3); 5. Boiling point: 6. Melting point: 7. Flash point: meaninglessness; 8. Purity: --; [ Storage Conditions and expiry date ] This product should be stored at room temperature in a dry place away from light, to avoid contact with acids, alkalis and other liquids, long-term storage will occur slow oxidation. [ Test method ] Crystal results can be confirmed by X-ray powder diffractometer. Confirmation of element composition by energy dispersive X-ray detector; The morphology of particles was characterized by the same morphology characterization. The particle size distribution was evaluated by laser particle size analyzer. [ Safety Protection ] 1. Health hazards Hazard category: Non-hazardous chemicals Chemical category: ceramic powder; Invasion route: inhalation, ingestion; Health hazards: dust irritates the eyes, oral irritation of the gastrointestinal tract; 2. First aid measures Skin contact: Take off the contaminated clothing and rinse the skin thoroughly with flowing water; Eye contact: Lift eyelids and rinse with plenty of running water or saline for at least 15 minutes; Inhalation: quickly leave the scene to the fresh air; Ingestion: Drink enough warm water, induce vomiting, medical treatment; 3. Ignition and explosion characteristics and fire protection Combustibility: non-flammable;

xperimental procedure description 1 1 gmoalb powder is mixed with 100ml 25wt%NaOH solution 2 Transfer mixture to 100ml autoclave 3 Autoclave 150℃, 24h heating 5 Wash with 1M NaOH dilute solution for 3 times and deionized water for 5 times until PH≈7-8 6 Prepared powder, 80℃, vacuum drying for 10h 7 25g (NaOH) /75ml(water)+25g (NaOH)

[ Storage Conditions and expiry date ] This product should be stored at room temperature in a dry place away from light, to avoid contact with acids, alkalis and other liquids, long-term storage will occur slow oxidation. [ Test method ] Crystal results can be confirmed by X-ray powder diffractometer. Confirmation of element composition by energy dispersive X-ray detector; The morphology of particles was characterized by the same morphology characterization. The particle size distribution was evaluated by laser particle size analyzer. [ Safety Protection ] 1. Health hazards Hazard category: Non-hazardous chemicals Chemical category: ceramic powder; Invasion route: inhalation, ingestion; Health hazards: dust irritates the eyes, oral irritation of the gastrointestinal tract; 2. First aid measures Skin contact: Take off the contaminated clothing and rinse the skin thoroughly with flowing water; Eye contact: Lift eyelids and rinse with plenty of running water or saline for at least 15 minutes; Inhalation: quickly leave the scene to the fresh air; Ingestion: Drink enough warm water, induce vomiting, medical treatment; 3. Ignition and explosion characteristics and fire protection Flammability: non-flammable

Prog. Mater. Sci. (IF:48.165) | 2D MXene and carbonProg. Mater. Sci. (IF:48.165) | 2D MXene and carbonProg. Mater. Sci. (IF:48.165) | 2D MXene and carbonProg. Mater. Sci. (IF:48.165) | 2D MXene and carbonProg. Mater. Sci. (IF:48.165) | 2D MXene and carbonProg. Mater. Sci. (IF:48.165) | 2D MXene and carbon

You can lubricate bicycle chains with oil, but what about hot conveyor belts in the steel industry or on Mars rovers? The Vienna University of Technology has now studied very special nanomaterials together with research groups from Saarbrucken (Germany), Purdue University in the United States and the University of Chile (Santiago, Chile). In recent years, MXenes' material category (pronounced "maxene") has caused a stir in connection with new battery technologies. But now they are also proving to be an excellent solid lubricant, extremely durable and capable of performing their tasks even in the most difficult conditions. These superior properties of MXenes have now been published in the prestigious ACS Nano journal. ust like the carbon material graphene, MXene falls into the category of so-called 2D materials: they are ultra-thin layers of single atoms and have no strong bonds to the upper or lower layers. Professor Carsten Gachot, head of the tribology group at TU's Institute of Engineering Design and Product Development, says you first start with the so-called MAX stage, which is a system of special layers made up of titanium, aluminium and carbon. The key trick is to etch aluminum with hydrofluoric acid. Then what's left is a bunch of atoms and thin layers of titanium and carbon that are loosely stacked together like pieces of paper. Each layer is relatively stable on its own, but the layers can easily move relative to each other. This portability between atomic layers makes the material an excellent dry lubricant: sliding with very low resistance can be achieved without causing wear. As a result, the friction between the steel surfaces can be reduced to one-sixth, and the wear resistance is extremely high: the MXene lubrication layer still works properly even after 100,000 movement cycles. This is ideal for use in difficult conditions: in space flight, for example, lubricating oil evaporates immediately in a vacuum, but MXene in fine powder form can also be used there. It has nothing to do with atmosphere or temperature Carsten Gachot says similar approaches have been tried for other thin film materials, such as graphene or molybdenum disulfide. But they respond sensitively to moisture in the atmosphere. Water molecules can change the bonding force between the layers. For MXene, on the other hand, it has less effect. Another decisive advantage is the heat resistance of MXenes, as many lubricants oxidize and lose their lubricity at high temperatures. MXenes, on the other hand, is more stable and can even be used in the steel industry, where parts that sometimes move mechanically sometimes reach temperatures of several hundred degrees Celsius. Dr Philip Grutzmacher of Professor Gachot's research group, together with the University of Saarbruken in Saarbruken and Purdue University in the US, studied the powder lubricant in several experiments at TU Wien. On the other side of the world, Professor Andreas Rosenkranz in Chile was instrumental in initiating and designing this work. Carsten Gachot says there has also been significant interest in the materials from industry. We think this MXene can be mass-produced very quickly.

MXene is a class of two-dimensional inorganic compounds in materials science. These materials consist of transition metal carbides, nitrides, or carbon nitrides several atomic layers thick. It first appeared in 2011 because MXene materials have the metal conductivity of transition metal carbides due to the hydroxyl group or terminal oxygen on their surface. It is widely used in supercapacitors, batteries, electromagnetic interference shielding and composite materials. For example, unlike conventional batteries, the material provides more channels for the movement of ions, greatly increasing the speed of ion movement. Scientists have developed MXene materials that synthesize substrates from the corresponding MAX phase, usually by selectively etching the main group A element, where M represents the transition metal, X represents carbon or nitrogen, and the main group A element can include aluminum, gallium, silicon, and other elements. Researchers typically perform etching in an aqueous hydrogen fluoride (HF) solution to make MXene have a mixture of fluoride, oxygen, and hydroxide functional groups. Unlike the surfaces of other two-dimensional materials, such as graphene and transitional carbon dihalides, functional groups can also be chemically modified. Previous studies have shown that selective termination of MXene with different surface groups can lead to excellent properties, including tunable work functions and two-dimensional ferromagnetism. The covalent functionalization of substrates will lead to the discovery of new directions for rational design of two-dimensional functional materials. Surface functional groups in two-dimensional transition metal carbides can undergo a variety of chemical transformations to facilitate the use of a wide range of MXene materials. A research team of chemistry, physics, and nanomaterials scientists from the University of Chicago and Argonne National Laboratory has designed and developed a novel pathway for MXene synthesis. They install and remove surface groups through substitution and elimination reactions in molten inorganic salts. The team successfully synthesized MXene with surface ends of oxygen, imide, sulfur, chlorine, selenium, bromine and tellurium with unique structural and electronic properties, and these surface groups can also control the interatomic distance in the MXene lattice to show superconductivity dependent on the surface groups.

With the increasing demand for wearable electronic products, flexible energy storage devices have been rapidly developed. MXenes is considered as a promising flexible electrode due to its ultra-high volumetric capacity, metal conductivity, superior hydrophilicity and rich surface chemistry. Pure MXene, MXene carbon composites, MXene metal oxide composites and MXene polymer composites have applications in flexible electronic devices such as sensors, nanogenerators and electromagnetic interference shielding. In addition, the application of MXenes materials in flexible devices affects the stress, strain, conductivity, capacitance and other properties are compared to help researchers maintain a balance between mechanical and electrochemical properties when designing flexible devices. 01 Flexible supercapacitor Flexible supercapacitors (SCs) are expected to achieve higher energy density per unit volume compared to traditional carbon-based materials batteries. First, the MXene material exhibits an extremely high volumetric energy density due to its high energy density and large Faraday pseudocapacitance (derived from rich surface chemistry), in addition, MXene can also act as a fluid collector due to metal conductivity. A flexible electrode composed of a fluid collector and an active material is then expected to be built entirely on a flat mxene sheet to further increase the bulk energy density of the flexible SCs to power wear-resistant electrons. For flexible MXene-based composites, composites mainly consisting of mxene and carbon nanomaterials, mainly including reduced graphene oxide (rGO) and carbon nanotubes (CNT), etc., to prepare flexible thin film electrodes. This strategy effectively prevents the reaccumulation of MXene sheets and significantly improves the flexibility. Polymers are another promising additive that can be combined with mxenes to greatly improve the mechanical properties of materials, especially conductive polymers, which can optimize mechanical strength without sacrificing electrical conductivity. In addition, metal oxides with high Faraday pseudocapacitance can also be used to bond with MXene for higher electrochemical properties. These nanocomposite methods facilitate the preparation of flexible MXene-based SCs, which have excellent flexibility, high specific capacity, and excellent mechanical properties to power wearable electronics.

MXene is a two-dimensional material, which is a kind of transition metal carbide, transition metal nitride or transition metal carbonitride with two-dimensional layered structure. It is a new material obtained by MAX phase treatment and has a structure similar to graphene. MXene was discovered in 2011 at Drexel University in the United States, where it was first discovered as a transition metal carbide with good electrical conductivity. MXene can be prepared by etching the MAX phase with an etching solution containing fluorine, such as hydrofluoric acid, etc. There are many kinds of MAX phase products, and a variety of MXene with different properties can be eroded by using MAX phase. At present, the MXene has been developed and published mainly Ti3C2Tx, Ti2CTx, Nb2CTx, Mo2CTx, Ti4N3Tx, Ta4C3Tx, Cr2TiC2Tx, V2CTx, Zr3C2Tx, (Nb0.8Zr0.2)4C3Tx and so on. Among them, Ti3C2Tx was first developed and came out, and the most research at this stage. According to the "2022-2026 MXene Industry In-depth Market Research and Investment Strategy Recommendation Report" released by Xinsiji Industry Research Center, MXene has the typical characteristics of two-dimensional materials, with excellent electrical conductivity and good lubricity, using it as raw materials, it can develop film, fiber, aerogel, hydrogel and other product forms. It can also be used with high polymer to prepare multi-functional composite materials. MXene can be widely used in photothermal conversion, field effect transistors, topological insulators, sensors, energy storage, electromagnetic shielding, catalysis, lubrication and other fields, so its research and development has attracted attention. In the field of batteries, because MXene can provide more channels, which can greatly increase the speed of ion movement, it has excellent electrical conductivity and can replace traditional conductive materials copper and aluminum. The battery made of MXene is used in the field of smart phones, which can speed up the charging speed of mobile phones and shorten the charging time of mobile phones. In the future, with the increasing maturity of technological research, MXene batteries can also be applied to the field of new energy vehicles, shorten the charging time of power batteries, and promote the penetration rate of new energy vehicles. MXene was developed in the United States, since 2011, China's research enthusiasm for MXene is high, at this stage in many regions of China have universities or scientific research institutions to conduct MXene research. There are more than 50 universities and research institutions studying MXene in China. There are mainly Dalian Institute of Chemical Sciences, Institute of Metals, Ningbo Institute of Materials, Harbin Engineering University, Dalian University of Technology, Shandong University, Beijing University of Aeronautics and Astronautics, Peking University, Tsinghua University, Nankai University, Henan Polytechnic University, Huazhong University of Science and Technology, South China University of Technology, Sichuan University, Fudan University, etc. Industry analysts said that China's semiconductor, sensor, electronics, new energy vehicles and other industries are developing rapidly, technology continues to upgrade, the market demand for high-performance materials continues to grow, two-dimensional materials with excellent performance attention, MXene as a new two-dimensional material, research continues to deepen. China's MXene research results continue to increase, and new MXene products with better performance are coming out one after another. In the future, with the increasing maturity of MXene technology, enterprises that can take the lead in realizing the industrialization of research results will have a first-mover advantage.

Evaluating the delamination process in the synthesis of MXenes (two-dimensional transition metal carbides and nitrides) is critical for their development and application. However, preparing large, defect-free MXene flakes with high yields is challenging. Here, a power-centered delamination (PFD) strategy is demonstrated that can improve the delamination efficiency and yield of large Ti3C2Tx MXene nanosheets through repeated precipitation and vortex oscillation processes. According to the protocol, Ti3C2Tx MXene has a colloidal concentration of 20.4 mg ml-1, which can be achieved after five PFD cycles, and a 61.2% Ti3C2Tx nanosheet free of base surface defects is obtained, 6.4 times higher than that obtained using ultrasonic stripping. Both nanothin devices and self-supporting films exhibit excellent electrical conductivity (approximately 25,000 and 8260 S cm-1 for 1.8 nm thick monolayers and 11 µm thick films, respectively). Hydrodynamic simulations show that the PFD method can effectively concentrate shear stress on the surface of the unstripped material, resulting in the stripping of the nanosheets. Large MXene nanosheets synthesized by PFD exhibit excellent electrical conductivity and electromagnetic shielding (shielding efficiency per unit volume: 35 419 dB cm 2 g-1). Therefore, PFD strategy provides an effective way to prepare high-performance single-layer MXene nanosheets with large area and high yield