MAX/MAB phases are a series of non-van der Waals ternary layered ceramic materials with a hexagonal structure, rich in elemental composition and crystal structure, and embody physical properties of both ceramics and metals. They exhibit great potential for applications in extreme environments such as high temperature, strong corrosion, and irradiation. In recent years, two-dimensional (2D) materials derived from the MAX/MAB phase (MXene and MBene) have attracted enormous interest in the fields of materials physics and materials chemistry and become a new 2D van der Waals material after graphene and transition metal dichalcogenides. Therefore, structural modulation of MAX/MAB phase materials is essential for understanding the intrinsic properties of this broad class of layered ceramics and for investigating the functional properties of their derived structures. In this paper, we summarize new developments in MAX/MAB phases in recent years in terms of structural modulation, theoretical calculation, and fundamental application research and provide an outlook on the key challenges and prospects for the future development of these layered materials.

Microstructural design is a promising strategy to enhance the toughness and plasticity of structural ceramics while maintaining their inherently excellent hardness, which can facilitate their applications in extreme environments. In this work, the possibility of establishing a symbiotic structure with metal atomic-layer phase-separation (MALPS) in carbide structural ceramics was investigated. The carbide ceramic samples were synthesized from raw materials comprising transition metals with different component numbers, graphite powders, and a small amount of aluminum by spark plasma sintering at 1900 ℃ and under a pressure of 30 MPa. It was found that Al-MALPS structure was observed exclusively in the high-entropy (TiZrHfNbTa)C ceramic, which was not a MAX phase with long-range-order but rather a composite featuring a non-periodic cross-stacking of single metal atomic layers within the carbide matrix. Characterization by spherical aberration correction transmission electron microscopy and energy dispersive spectroscopy from nanometer to atomic scales revealed that the single Al atomic layers were sparsely embedded onto the {111} planes of the carbide face-centered cubic structure. Combined with the first-principles calculations, the formation of MALPS structure was found to be driven by thermodynamic stability, lattice distortion, and sluggish-diffusion effect of high entropy, rather than the differential diffusion of Al in various carbide lattices. This work could promote the design and regulation of atomic-scale microstructures in structural ceramics, aiming for high performance with synergetic high hardness-strength-toughness.

Ti₂AlC is considered to be one of the compounds with the best antioxidant properties in MAX phase materials, with potential application prospects in the field of high-temperature structural materials and high-temperature antioxidant protective coatings. However, the low hardness and strength of single phase Ti₂AlC limit its wide application in the field of high-temperature material. In order to improve the properties of Ti₂AlC, Ti₂AlC-20%TiB₂ (in volume) composites (referred to as Ti₂AlC-20TiB₂) were synthesized by the in-situ solid-liquid phase reaction/hot pressing method. Besides, the high temperature oxidation behavior in the temperature range of 1000-1300 ℃ was studied, and the oxidation resistance mechanism at high temperature was analyzed. The results show that the oxidation kinetics of Ti₂AlC-20TiB₂ composites is logarithmic, exhibiting superior oxidation resistance compared to single phase Ti₂AlC. Below 1200 ℃, the oxide scale is mainly composed of an inner layer of Al₂O₃ and an outer layer of TiO₂, while the outer layer of oxide scale is a mixture of TiO₂ and Al₂TiO₅ at 1300 ℃. The Al₂O₃ protective layer formed in the composite is denser than that in single-phase Ti₂AlC, which is the key to its excellent antioxidant performance. The addition of TiB₂ reduces the grain size of the material and increases the number of grain boundaries for short-circuit diffusion, which facilitates the selective oxidation of Al and accelerates the formation of Al₂O₃ protective layer. Additionally, B₂O₃ produced during the oxidation of TiB₂ can effectively fill the micropores and repair microcracks, thereby preventing the internal diffusion of O and further enhancing the antioxidant properties of the composites.

Silicon carbide ceramics are important engineering materials, but their application is limited by the inherent brittleness. Two-dimensional graphene, with its excellent properties, can be used as a second phase to improve the performance of silicon carbide ceramics. However, due to poor dispersion of graphene in the ceramic matrix, it is a challenge to fully exploit the modifying effect of graphene in composite materials. To address these challenges, SiC-based ceramic materials incorporating graphene nanosheets (GNPs) were synthesized using ceramic organic precursor polycarbosilane and industrial expandable graphite as starting materials. The precursor intercalation technique was employed to fabricate SiC/GNPs ceramic composites with GNPs volume fraction of 1%, 3%, and 5%. The GNPs were uniformly arranged in an array-like parallel fashion in the SiC ceramic matrix, showing excellent orientation. With the GNPs content increasing, the spacing between GNPs within the array decreased, indicating tunable microstructural topology. The addition of GNPs greatly enhanced the fracture toughness of SiC ceramics. When the GNPs content was 3%, the relative density of the samples reached 98.5%, the bending strength reached 445 MPa, and the fracture toughness (K_IC value) peaked at 5.67 MPa·m^1/2, surpassing pure SiC ceramics by 40%, which was primarily attributed to crack deflection and bridging induced by the GNPs. However, further increase in GNPs content led to a decrease in fracture toughness to 4.37 MPa·m^1/2. These SiC-based ceramic composites with a graphene array have potential application in design and development of novel “structure-function integration” SiC-based ceramic devices.

Development of electrode materials with high activity and stability is a key issue to achieve efficient degradation of sulfonamide pollutants by electro-Fenton (EF) system. In this work, FePc/MXene nanocomposites were prepared by using MXene material as carrier to load iron phthalocyanine (FePc) and employed as cathodic catalyst to construct EF system for the degradation of sulfadimethoxine (SDM). After loading FePc, the nanomaterials retained accordion-like lamellar structure with slightly roughened surface and narrowed interlayer spacing. Coordination number of FeN_x in FePc/MXene was about 4, in which the interaction between FePc and MXene was favorable to promote the electron transfer at the electrode surface. In the EF system, the FePc/MXene electrode achieved a 97.2% degradation rate of SDM within 50 min, showing excellent catalytic performance and stability over wide pH range. The significant improvement in degradation performance was mainly attributed to the enhanced activity of O₂ electrocatalytic reduction to H₂O₂ by the introduction of FeN₄ in the composites. Free radical (·OH and ·O₂^-) and non-radical (¹O₂) pathways were co-operative in the degradation of SDM by EF system. Frontier orbital theory and Fukui function theoretically elucidated the sites where SDM was attacked by different reactive oxygen species, primarily degrading through hydroxylation of the benzene ring, oxidation of the amino group on the benzene ring, and cleavage of C-S and S-N bonds. In addition, cycling and ion leaching experiments demonstrated the excellent stability of the prepared cathode catalysts.

MXenes with two-dimensional layered structure are widely used in the field of potassium ion supercapacitors because of their excellent electrical properties and adjustable surface functional groups, but their limited dual-capacitor storage capacity severely retards the application of MXenes materials in electrode materials. In this work, the strategy of “Lewis acid molten salt pre-etching + liquid phase etching + in situ hydrothermal recombination” was used to prepare the Ti₃C₂-based heterojunction with Ti₃C₂ as matrix and MnO₂ coated surface to improve the storage of potassium ions in electrode materials. The connection mode, electrical properties and the change of potassium adsorption law at Ti₃C₂-based heterojunction interfaces were studied by using the first principles calculation method based on density functional theory. The results show that the maximum adsorption capacity of potassium ions in the constructed Ti₃C₂-based heterojunction is about 3 times that of Ti₃C₂. The presence of Ti-O-H-O connecting channel increases the number of free electrons in MnO₂, causing Ti₃C₂-based heterojunction exhibiting excellent electrical properties. The electrochemical test results of the three-electrode system show that, at a current density of 1 A·g^-1, Ti₃C₂-based heterojunction can provide 431 F·g^-1 specific capacitance which is much higher than 128 F·g^-1 of bare Ti₃C₂. At a voltage sweep rate of 100 mV·s^-1, the contribution of pseudocapacitance is up to 89%. In addition, the Ti₃C₂-based heterojunction exhibits lower electrochemical impedance, which improves the potassium ion transport rate and electron transfer rate. Therefore, this study demonstrates that the electrochemical performance of Ti₃C₂ matrix can be improved by constructing Ti₃C₂-based heterojunction, and the corresponding energy storage mechanism can provide a theoretical basis for the design of other MXenes-based electrode materials.

The poor oxidation resistance and structural stability of Ti₃C₂(OH)₂ largely limit its wide applications. In this work, the surface adsorption behaviors of oxygen atoms on Ti₃C₂(OH)₂, polyaniline (PANI) and PANI/Ti₃C₂(OH)₂ composite were systematically studied and compared by first-principles calculation method. The simulation results suggest that the existence of -OH functional group can change the active sites on Ti₃C₂ matrix. Thereby the oxidation resistance and the structural stability of Ti₃C₂ matrix can be improved in some extent. Furthermore, after modifying Ti₃C₂(OH)₂ by PANI, the adsorption activity of PANI is much larger. Meanwhile, the adsorption energy of oxygen on the Ti₃C₂(OH)₂ end is significantly decreased, which is caused by the electron transfer from PANI to Ti₃C₂(OH)₂, as confirmed by the Bader charge calculation. Therefore, the oxidation resistance and the structural stability of the PANI modified Ti₃C₂(OH)₂ composite are improved by sacrificing PANI, since oxygen prefers to adsorb and attack PANI firstly. This work provides theoretical guidelines for the improvement of oxidation resistance, structural and chemical stability of MXene.

TiO₂ nanomaterials are widely used photocatalysts due to high photocatalytic activity, good chemical stability, low cost, and nontoxicity. However, its lower photon utilization efficiency is still limited by larger bandgap width and higher recombination rate between photon and hole. In this study, two-dimensional TiO₂ nanosheets were synthesized via microetching, which were then inserted by ruthenium atoms to form an efficient photocatalyst Ru@TiO₂ with sandwich structure. The surface morphology, electronic structure, photoelectric properties, and photocatalytic degradation performance of tetracycline hydrochloride of Ru@TiO₂ sandwich structure were investigated using different measurements. Results indicated that the material’s photoresponse range extended from UV to visible- near-infrared regions, improving photon absorption and carrier separation efficiency while enhancing photocatalytic activity. Under simulated sunlight irradiation (AM 1.5 G, 100 mW·cm^-2) for 80 min, sandwich structured Ru@TiO₂ efficient photocatalyst exhibited superior degradation performance on tetracycline hydrochloride with a degradation efficiency up to 91.91%. This work offers an effective way for the construction of efficient TiO₂ based photocatalysts.

Inspired by gene scissor concept in biological genetic engineering, chemical scissors, as important research tools, play an important role in the study of structure editing and application of materials. We aim to review the research progress of chemical scissors in structural editing and applications of materials. First of all, we introduce the basic concept and mechanism. Chemical scissors strategy refers to a methodology for material editing through which the main crystal structure is preserved but targeted atoms or structural units are knocked out, replaced, repaired or reconstructed in order to realize special functionality. Subsequently, the specific applications of chemical scissors in materials structure editing are discussed in depth, including the methods and functional designs for precise structure modulation of materials by chemical shearing, modification, synthesis, as well as etching and intercalation. Finally, the future research direction of chemical scissors in the field of material structure editing is envisioned, including developing new chemical scissors that are more intelligent and efficient, exploring more innovative strategies for material structure editing, understanding the underlying chemical mechanism, and further expanding the applicability of chemical scissors. Overall, we summarize the research progress and potential of material structural editing, which provides important theoretical and experimental support for further exploring and developing the application of chemical scissors in the field of materials.

Developing novel low-dimensional materials for terahertz electromagnetic shielding and absorbing applications represents a critical research frontier. Their unique electrical, mechanical, and electromagnetic responses hold great potential in enabling more efficient solutions for electromagnetic shielding and absorbing. Two-dimensional transition metal carbides, nitrides, and carbonitride MXenes have already demonstrated excellent electromagnetic shielding and absorbing performance in the low-frequency spectrum. MXenes possess high conductivity, low density, and high flexibility, which are advantageous for future portability and integration of terahertz devices and systems. However, practical implementation of MXene-based terahertz electromagnetic shielding and absorption materials faces challenges in adhesion stability, environmental resilience, and high-temperature tolerance, hindering their suitability for aerospace and future next generation communication applications. Moreover, in terahertz frequency band, lacking more comprehensive and reliable electromagnetic scattering and absorbing measurement methods limits the development of THz shielding and absorbing materials. Extensive research efforts have targeted on these limitations, exploring fundamental architectural and theoretical aspects of prevalent electromagnetic materials. This review specifically highlights the terahertz electromagnetic shielding and absorption characteristics inherent in various MXenes and their compositions, such as Ti₃C₂T_x, Mo₂Ti₂C₃T_x, Mo₂TiC₂T_x, Nb₄C₃T_x, and Nb₂CT_x. Additionally, this review envisages the forthcoming challenges and prospects of MXenes as a pivotal electromagnetic shielding and absorbing material within the terahertz frequency band.

MAX phase ceramics, with their mixed covalent-metallic-ionic atomic bonds, can uniquely combine the advantages of both metals and ceramics, offering a series of distinctive characteristics. The particular layered atomic structure further endows them with decent fracture toughness, good damping capacity, and self-lubricating property. As such, MAX phase ceramics are more appealing to serve as reinforcements for metal matrix composites (MMCs) than conventional ceramic materials. Here, we foused on the development. To date, fabrication of MMCs reinforced by MAX phase ceramics still involves the use of stir casting, powder metallurgy, and melt infiltration techniques. The obtained composites made by different methods may display distinct differences in their structural characteristics, show notable enhancement in strength, hardness, and stiffness as compared to their metal matrices, and exhibit good wear resistance, high electrical conductivity and remarkable arc erosion resistance. Moreover, ultrafine MAX phase platelets can be preferentially oriented and aligned, e.g., by using vacuum filtration or ice templating techniques. By infiltrating metal melt into partially sintered porous ceramic scaffolds, bioinspired composites with nacre-like architectures can be obtained, thereby affording further improvement in strength and fracture toughness. Sufficient combinations of mechanical and functional properties enable the MMCs reinforced by MAX phase ceramics promising for a variety of applications, such as load-bearing structures, electrical contact materials. These composites can offer enhanced strength, stiffness, and wear resistance, making them ideal candidates for these applications.

Two-dimensional transition metal carbon/nitride MXenes show promising applications in various fields due to their remarkable electrical and mechanical properties. Recently, the research of high performance MXenes nanocomposites (including one-dimensional fibers, two-dimensional films and three-dimensional blocks) has made remarkable progress. However, the mechanical properties are still far lower than the intrinsic mechanical properties of MXenes nanosheets, mainly due to the key scientific problems of voids, misalignment of MXenes nanosheets and weak interfaces. In order to solve the above problems, the intrinsic mechanical properties of MXenes nanosheets are firstly discussed in this work, then the development of high performance MXenes nanocomposites are summarized, and the latest research progress of high performance MXenes nanocomposites is discussed in detail, including how to eliminate void, improve the orientation of MXene nanosheets and enhance the interface interaction. Meanwhile, the applications of high performance MXenes nanocomposites in the fields of electric heating, thermal camouflage, electromagnetic shielding, sensing and energy storage are introduced. Finally, the challenges and future development directions of high performance MXenes nanocomposites are proposed.

MXene is a large family of two-dimensional transition metal carbides, nitrides or carbonitrides. Its characteristics (various compositions, two-dimensional atomic layer structures, metallic electrical conduction, active surfaces, etc.) render MXene unique interactions with electromagnetic waves at different frequencies (visible light, infrared, terahertz, microwave, etc.), deriving a variety of electromagnetic functional applications. In the infrared range, MXene has a wide range of infrared radiation properties, and its active surface endows tunable infrared absorption. These features have attracted researchers’ interest in exploring infrared properties of MXene and the corresponding applications in recent years. In this perspective, the intrinsic infrared characteristics and manipulation strategies of different MXenes are systematically summarized, and the research progress of representative infrared applications are briefly introduced, including infrared identification/camouflage, surface plasmon, photothermal conversion, and infrared photodetection. Particularly, the contribution and mechanism of MXene in these applications are discussed. Finally, the outlook for infrared functional applications with MXenes is proposed.

Atomic-thin transition metal carbonitrides (MXenes), as an emerging class of two-dimensional (2D) materials, become a highly active research topic. Since the discovery of graphene nearly 20 years ago, many 2D materials (graphene, transition metal dichalcogenides, and black phosphorus) have been extensively studied in the field of micro-nano electronics. However, research on MXenes-based micro-nano electronics has just begun. MXenes exhibit rich elemental compositions and unique physicochemical properties, such as hydrophilicity, tunable work function, adjustable functional groups, fast ion and electron transport, superconductivity, surface plasmons, photo- thermo-electricity, and electromagnetic absorption, and some MXenes even possess high conductivity. These characteristics make MXenes hold great potential for device applications at the microscale or even nanoscale. In recent years, the Alshareef research group has been dedicated to bringing MXenes into the field of micro-nano electronics and has defined the emerging academic field of MXene electronics, known as MXetronics, in 2019. This perspective briefly summarizes and evaluates representative research progress in this field, including the challenges in synthesis, processing, property investigation, and device applications at the microelectronic level. Furthermore, we will propose several key research directions and unexplored subfields in this area.

In recent years, pressure sensors have been widely applied in the fields of smart wearable textile, health detection, and electronic skin. The emergence of the two-dimensional nanomaterial MXene has brought a brand-new breakthrough for pressure sensing. Ti₃C₂T_x is the most popular studied MXene in the field of pressure sensing and shows good mechanical, electrical properties, excellent hydrophilicity, and extensive modifiability, enabling it an ideal material for pressure sensing. Hence, researchers have conducted a lot of explorations and studies on design and application of MXene in pressure sensors in recent years. Herein, the preparation technologies and antioxidant methods are summarized. Design of MXene-based microstructures is also introduced, including aerogels/porous structural materials, hydrogels, flexible substrates, and films, which are beneficial to improve the response range, sensitivity, and flexibility of pressure sensors, and promote the rapid development of pressure sensors. The mechanisms of MXene pressure sensors are further broached, including piezoresistive, capacitive, piezoelectric, triboelectric, battery typed and nanofluidic. MXene has been applied in a wide range of sensors for various mechanisms due to its excellent characteristics. Finally, the chance and challenge in the synthesis, properties, and pressure sensing performance of MXene materials are prospected.

Two-dimensional (2D) transition metal carbides/nitrides (MXenes), since their discovery in 2011, have attracted great attention in the fields of energy storage, catalysis, sensors, electromagnetic interference shielding and microwave absorption and so on, owing to their special 2D layered structure, excellent electrical conductivity and electrochemical properties. In recent years, with the deep understanding of MXenes, the research on the realm related to optoelectronic properties has been widely concerned. Unlike other application fields, optoelectronic devices based on MXenes focus on extending semiconductor properties, including tunable band gap of the MXenes via design of the surface functional groups and layer control, etc., so as to achieve their transformation from metal to semiconductor properties. This paper revolves around the photoelectric properties of MXenes, mainly introduce its application in flexible optoelectronic devices, and systematically describe their current status and trend in transparent electronic devices, photodetectors, image sensors, transistors, and artificial neural vision network systems. The challenges and future development prospects of MXenes-based flexible optoelectronic devices are also proposed.

Advanced ink printing techniques, such as printing and coating, have overcome the limitations of traditional manufacturing methods, allowing for rapid prototyping of films and electronic devices with sophisticated structures and specific functions. These techniques hold enormous potential in wearable smart identification, energy storage, electromagnetic shielding and absorption, touch display, and so on. The key to printing advanced energy and electronic devices lies in the development of cutting-edge functional inks and their corresponding printing technologies. MXene, a family of two-dimensional compounds composed of transition metal carbides, nitrides, or carbonitrides, was discovered in 2011. MXene exhibits remarkable physical and chemical properties, including high conductivity, pronounced hydrophilicity, and diverse surface chemistry, which has garnered significant attention within the research community and made it particularly suitable as inks in printing applications. Conducting research on the printing behavior and mechanisms of MXene inks is crucial not only for achieving high-precision patterns but also for establishing a solid foundation for manufacturing techniques that can precisely create multiscale, multimaterial and multifunctional films, and electronic devices. This article begins with a brief discussion of MXene flakes’ synthesis and colloidal stability, followed by a detailed examination of its rheological characteristics, printable ink formulation, and printing methods. Additional, special attention is given to the latest advances of MXene ink in energy, health, and sensing applications. The perspective concludes with a summary of current research challenges and future directions in this area, offering new perspectives and insights for researchers.

Rechargeable zinc-ion batteries (ZIBs) have captured significant attention as promising solutions for large-scale energy storage. They offer advantages such as low cost, inherent safety, high specific energy, and eco-friendliness. Though numerous breakthroughs have been achieved in the development of cathodes, anodes and electrolytes, ZIBs are still far behind for practical application due to the lack of advanced materials. In the realm of ZIBs, two-dimensional (2D) MXenes have emerged as a fascinating candidate, leveraging their exceptional properties such as high richness, customizability, and unique physiochemical attributes. This review aims to provide a concise overview of advancements in MXene application for ZIBs, encompassing multiple synthesis routes, properties, morphological and structural characteristics, as well as various chemistries employed. Furthermore, detailed elucidation is provided on the recent progress in MXene-based cathodes, anodes, and electrolytes/separators for ZIBs, indicating the great potential of MXenes for achieving high-performance ZIBs. Strategies to enhance the performance of MXene-based ZIBs are also highlighted, including ion-intercalation adjustment, surface modification, heteroatoms doping, and layer spacing widening. Lastly, the review discusses the current challenges and future prospects for MXene-based ZIBs, paving the way for further research and development in this exciting field.

As renewable and sustainable clean energy, solar energy has the potential to address current energy shortage and reduce environmental pollution caused by fossil fuels consumption. In recent years, the third-generation thin-film solar cells, such as dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs), have attracted widespread attention due to their low cost, abundant materials, and high photoelectric performance. However, these devices still face challenges in terms of charge transfer efficiency and operational stability for their commercialization. Two-dimensional (2D) MXene materials have emerged as promising candidates for improving the performance of thin-film solar cells due to their unique properties, including high specific surface area, rich surface functional groups, high conductivity, tunable work function, and hydrophilicity. This review summarizes the recent research progress of 2D MXene materials applied in new thin-film solar cells, focusing on the reaction mechanism that enhances the photoelectric performance of solar cells. Strategies such as using 2D MXene materials as additives for the perovskite layer and charge transport layer in PSCs, modifying the photoanode in DSSCs, and preparing varous electrodes, can effectively improve light absorption efficiency, carrier mobility, and charge extraction capability of the devices by adjusting band alignment, reducing work function, broadening the light absorption range, and creating a “pillar support effect”. As a result, the photoelectric performance and stability of the devices are enhanced. In conclusion, the perspectives highlights the current research progress and challenge faced by 2D MXene materials in novel thin-film solar cells.

Zr₂SB, Hf₂SB, Zr₂SeB, Hf₂SeB, and Hf₂TeB are all recently discovered S-group elements containing MAX-phase borides, which attract much attention since the MAX phase borides are significantly unlike the typical MAX phases. Here, the phase stability, mechanical properties and thermal properties of MAX phase borides (M = Zr, Hf, A = S, Se, Te) were studied by using first principles and "linear optimization method", bond stiffness model and quasi-simple harmonic approximation. The results of the theoretical analysis were consistent with the currently available experimental results. Only M₂AB was found to be stable after thermodynamic and intrinsic stability analysis. The shorter M−A bond and M−B bond lengths cause bond stiffness of Hf lineage higher than that of Zr, which also leads to the higher hardness of Hf lineage compound than that of Zr. the A site element goes from S to Se and to Te, the bond lengths of M−B and M−A are gradually increased, which lead to decrease in the elastic modulus. Moreover, the bulk modulus of these compounds is determined by their average chemical bond stiffness. Importantly, the high k_min/k_max (stiffness ratio of the weakest and the strongest bonds) shows that these MAX phases are inherently brittle, different from conventional MAX phase. Including the contribution of lattice vibration (phonon) and electron excitation, the isobaric heat capacity and heat expansion coefficient of M₂AB increase rapidly with increasing the temperature below 300 K and then the rise rate gradually decreases, similar to other MAX phases. Lower bond stiffness results in an overall higher TEC of MAX phase borides in the Zr lineage than in the Hf lineage. The TEC values of these compounds in the 300−1300 K interval are consistent with most of the MAX and MAB phases.

Two-dimensional (2D) perovskite displays great potential in optoelectronic applications due to its inherent quantum well structure, large exciton binding energy and good stability. However, facile preparation of high-quality 2D perovskite films with low cost remains a huge challenge. In this work, high-quality two-dimensional perovskite (PEA)₂PbI₄ films were prepared by solution method at low annealing temperature(80 ℃) without other special treatments, and further applied in the field of photodetectors. The results show that this photodetector possessed a low dark current (10^-11 A), good responsiveness illuminated at a wavelength of 450 nm (107 mA·W^-1), high detection rate (2.05×10¹² Jones) and fast response time (250 μs/330 μs). After 1200 s continuous illumination, the device maintains 95% initial photocurrent. In addition, the photocurrent remains almost unchanged after storage for 30 d. This work provides promising strategy to develop stable and high-performance optoelectronic devices.

Excessive emission of greenhouse gases has serious adverse effects on global climate. How to reduce carbon emissions has become a global problem. Supercapacitors have advantages of long cycle life, high power density and relatively low carbon emissions. Developing supercapacitor energy storage is an effective measure to build the reliable future energy system. In recent years, MXene materials have achievedgreat popularity in the field of supercapacitor energy storage applications due to their excellent hydrophilicity, electrical conductivity, high electrochemical stability, and surface chemical tunability. However, the serious self-stacking problem of MXene limits its performance in energy storage. Developing advanced MXene materials is critical for next generation high-performance electrochemical energy storage devices. This paper reviews the research progress of MXene material in the field of supercapacitor energy storage. Firstly, the structure and energy storage properties of MXene are introduced, followed by analysis of the energy storage mechanism of MXene. Secondly, nanoengineering of structure design to improve the performance of MXene electrode is depicted. Thirdly, structure-performance relationship of MXene composite materials and its latest research progress in application of supercapacitor are summarized. Finally, research and development trends of MXene as an electrode for supercapacitor are broadly prospected.

Ti₃C₂T_x MXene is a potential adsorbent of heavy metal ions due to its two-dimensional layered structure and abundant surface functional groups. However, it has disadvantages of limited layer spacing and poor stability in aqueous solution. Here, the modification strategy of Ti₃C₂T_x was explored to improve its chemical stability and ion adsorption capacity among which Fe₃O₄-Ti₃C₂T_x(FeMX) adsorbent with different doping amounts of Fe₃O₄ were prepared by one-step hydrothermal method. The results showed that the maximum theoretical Pb(II) adsorption capacity of FeMX adsorbent could reach 210.54 mg/g. Its adsorption mechanism was further revealed that Fe₃O₄ nanoparticles were evenly dispersed and intercalated between Ti₃C₂T_x nanosheets, which effectively increased specific surface area and layer spacing of Ti₃C₂T_x nanosheets, leading to improving Pb(II) removal ability. Therefore, this study provides a promising route for developing MXene matrix composites with excellent heavy metal ion adsorption properties.