Bimetal Organic Framework–Ti3C2Tx MXene with Metalloporphyrin Electrocatalyst for Lithium–Oxygen Batteries

The gravest oxidation of MXenes has become a critical problem due to the formation of metal oxides, leading to the loss of their intrinsic properties. Herein, bimetallic cobalt–manganese organic framework (CMT) directly grown on a Ti₃C₂T_x MXene sheet via solvothermal treatment to obtain strong oxidation resistance in an open structured application and to enhance electrocatalytic properties for oxygen evolution and reduction reaction is reported. Inspired by ligand chemistry, the carboxyl acids in tetrakis(4–carboxyphenyl)porphyrin acting as an organic linker are grafted with the surface terminators of Ti₃C₂T_x MXene through the Fischer esterification and substitution reaction of fluorine, thereby greatly enhancing the antioxidation stability. Furthermore, the as-formed metalloporphyrin structure and unpaired electrons, produced between CMT and Ti₃C₂T_x MXene during solvothermal treatment, improve their electrocatalytic activity, durability, and electrical conductivity through an electron hopping mechanism. Consequently, the CMT@MXene demonstrates high stability as a bifunctional electrocatalyst at a fixed specific capacity of 1000 mAh g⁻¹ and a current density of 500 mA g⁻¹ for 247 cycles in lithium–oxygen (Li O₂) battery. This approach suggests new strategies for the synergistic coupling of MXenes and MOFs for future open structured applications.     

Balancing MXene Surface Termination and Interlayer Spacing Enables Superior Microwave Absorption

Surface chemistry and interlayer engineering determines the electrical properties of 2D MXene. However, it remains challenging to regulate the surface and interfacial chemistry of MXene simultaneously. Herein, simultaneous modulation of Ti₃C₂T_x MXene surface termination and layer spacing by alkali treatment are achieved. The electrical and electromagnetic properties of Ti₃C₂T_x are investigated in detail with respect to KOH and ammonia concentration dependence. A high concentration of KOH caused the Ti₃C₂T_x layer spacing to expand to 13.7 Å and the surface O/F ratio to increase to 33.84. Because of its weaker ionization effect, ammonia provides finer tuning compared to the drastic intercalation of KOH with a thorough sweeping of the F-containing groups. Ti₃C₂T_x is enriched with conductive -OH termination after ammonia treatment, which achieves an effective balance with the increased interlayer resistance. Therefore, NH₃H₂O-Ti₃C₂T_x achieves broad-band impedance matching and exhibits an efficient microwave loss of −49.1 dB at a low thickness of 1.7 mm, with an effective frequency bandwidth of 3.9 GHz. The results herein optimize the electrical properties of Ti₃C₂T_x using surface and interfacial chemistry to achieve broad microwave absorption, providing a framework for enhancing the electromagnetic wave loss of intrinsic MXene.     

A Self-Assembled Vertical-Gradient and Well-Dispersed MXene Structure for Flexible Large-Area Perovskite Modules

Advancing hole transport layers (HTL) to realize large-area, flexible, and high-performance perovskite solar cells (PSCs) is one of the most challenging issues for its commercialization. Here, a self-assembled gradient Ti₃C₂T_x MXene incorporated PEDOT:PSS HTL is demonstrated to achieve high-performance large-area PSCs by establishing half-caramelization-based glucose-induced MXene redistribution. Through this process, the Ti₃C₂T_x MXene nanosheets are spontaneously dispersed and redistributed at the top region of HTL to form the unique gradient distribution structure composed of MXene:Glucose:PEDOT:PSS (MG-PEDOT). These results show that the MG-PEDOT HTL not only offers favorable energy level alignment and efficient charge extraction, but also improves the film quality of perovskite layer featuring enlarged grain size, lower trap density, and longer carrier lifetime. Consequently, the power conversion efficiency (PCE) of the flexible device based on MG-PEDOT HTL is increased by 36% compared to that of pristine PEDOT:PSS HTL. Meanwhile, the flexible perovskite solar minimodule (15 cm² area) using MG-PEDOT HTL achieve a PCE of 17.06%. The encapsulated modules show remarkable long-term storage stability at 85 °C in ambient air (≈90% efficiency retention after 1200 h) and enhanced operational lifetime (≈90% efficiency retention after 200 h). This new approach shows a promising future of the self-assembled HTLs for developing optoelectronic devices.     

Tetrabutylammonium Bromide Functionalized Ti3C2Tx MXene as Versatile Cathode Buffer Layer for Efficient and Stable Inverted Perovskite Solar Cells

2D Ti₃C₂T_x MXene, possessing facile preparation, high electrical conductivity, flexibility, and solution processability, shows good application potential for enhancing device performance of perovskite solar cells (PVSCs). In this study, tetrabutylammonium bromide functionalized Ti₃C₂T_x (TBAB-Ti₃C₂T_x) is developed as cathode buffer layer (CBL) to regulate the PCBM/Ag cathode interfacial property for the first time. By virtue of the charge transfer from TBAB to Ti₃C₂T_x demonstrated by electron paramagnetic resonance and density functional theory, the TBAB-Ti₃C₂T_x CBL with high electrical conductivity exhibits significantly reduced work function of 3.9 eV, which enables optimization of energy level alignment and enhancement of charge extraction. Moreover, the TBAB-Ti₃C₂T_x CBL can effectively inhibit the migration of iodine ions from perovskite layer to Ag cathode, which synergistically suppresses defect states and reduce charge recombination. Consequently, utilizing MAPbI₃ perovskite without post-treatment, the TBAB-Ti₃C₂T_x based device exhibits a dramatically improved power conversion efficiency of 21.65% with significantly improved operational stability, which is one of the best efficiencies reported for the devices based on MAPbI₃/PCBM with different CBLs. These results indicate that TBAB-Ti₃C₂T_x shall be a promising CBL for high-performance inverted PVSCs and inspire the further applications of quaternary ammonium functionalized MXenes in PVSCs.     

Surface‐Modified Metallic Ti3C2Tx MXene as Electron Transport Layer for Planar Heterojunction Perovskite Solar Cells

MXenes are a large and rapidly expanding family of 2D materials that, owing to their unique optoelectronic properties and tunable surface termination, find a wide range of applications including energy storage and energy conversion. In this work, Ti₃C₂T_x MXene nanosheets are applied as a novel type of electron transport layer (ETL) in low‐temperature processed planar‐structured perovskite solar cells (PSCs). Interestingly, simple UV‐ozone treatment of the metallic Ti₃C₂T_x that increases the surface Ti? O bonds without any change in its bulk properties such as high electron mobility improves its suitability as an ETL. Improved electron transfer and suppressed recombination at the ETL/perovskite interface results in augmentation of the power conversion efficiency (PCE) from 5.00% in the case of Ti₃C₂T_x without UV‐ozone treatment to the champion PCE of 17.17%, achieved using the Ti₃C₂T_x film after 30 min of UV‐ozone treatment. As the first report on the use of pure MXene layer as an ETL in PSCs, this work shows the great potential of MXenes to be used in PSCs and displays their promise for applications in photovoltaic technology in general.     

MXene-Based Anode-Free Magnesium Metal Battery

Rechargeable magnesium batteries (RMBs) are promising next-generation low-cost and high-energy devices. Among all RMBs, anode-free magnesium metal batteries that use in situ magnesium-plated current collectors as negative electrodes can afford optimal energy densities. However, anode-free magnesium metal batteries have remained elusive so far, as their practical application is plagued by low Mg plating/stripping efficiency due to nonuniform Mg deposition on conventional anode current collectors. Herein, for the first time, an anode-free Mg-metal battery is developed by employing a 3D MXene (Ti₃C₂T_x) film with horizontal Mg electrodeposition. The magnesiophilic oxygen and reactive fluorine terminations in MXene enable an enriched local magnesium-ion concentration and a durable magnesium fluoride-rich solid electrolyte interphase on the Ti₃C₂T_x film surface. Meanwhile, Ti₃C₂T_x MXene exhibits a high lattice geometrical fit with Mg (≈96%) to guide the horizontal electrodeposition of Mg. Consequently, the developed Ti₃C₂T_x film achieves reversible Mg plating/stripping with high Coulombic efficiencies (>99.4%) at high-current-density (5.0 mA cm⁻²) and high-Mg-utilization (50%) conditions. When this Ti₃C₂T_x film is coupled with a pre-magnesized Mo₆S₈ cathode, the anode-free Mg-metal full-cell prototype exhibits a volumetric energy density five times higher than its standard Mg-metal counterpart. This work provides insights into the rational design of anode current collectors to guide horizontal Mg electrodeposition for anode-free Mg metal batteries.     

High-Performance Ultraviolet Photodetectors Enabled by van der Waals Schottky Junction Based on TiO2 Nanorod Arrays/Au-Modulated Ti3C2Tx MXene

Two-dimensional transition metal carbides and nitrides (MXenes) show tremendous potential for optoelectronic devices due to their excellent electronic properties. Here, a high-performance ultraviolet photodetector based on TiO₂ nanorod arrays/Ti₃C₂T_x MXene van der Waals (vdW) Schottky junction by all-solution process technique is reported. The Ti₃C₂T_x MXene modulated by the Au electrode increases its work function from 4.41 to 5.14 eV to form a hole transport layer. Complemented by the dangling bond-free surface of Ti₃C₂T_x, the Fermi-level pinning effect is suppressed and the electric-field strength of the Schottky junction is enhanced, which promotes charge separation and transport. After applying a bias of −1.5 V, the photovoltaic effect is favorably reinforced, while the hole-trapping mechanism (between TiO₂ and oxygen) and reverse pyroelectric effect are largely eliminated. As a result, the responsivity and specific detectivity of the device with FTO/TiO₂ nanorod arrays/Ti₃C₂T_x/Au structure reach 1.95 × 10⁵ mA W⁻¹ and 4.3 × 10¹³ cm Hz^1/2 W⁻¹ (370 nm, 65 mW cm⁻²), respectively. This work provides an effective approach to enhance the performance of photodetectors by forming the vdW Schottky junction and choosing metal electrodes to modulate MXene as a suitable charge transport layer.     

Strategy Toward Semiconducting Ti3C2Tx-MXene: Phenylsulfonic Acid Groups Modified Ti3C2Tx as Photosensitive Material for Flexible Visual Sensory-Neuromorphic System

The excellent electronic and electrochemical properties make 2D MXenes suitable candidates for sensors, batteries, and supercapacitors. However, the metallic-like behavior of MXenes hinders their potential for optoelectronic devices such as photodetectors. In this study, the band gap of metalloid Ti₃C₂T_x MXene is successfully opened to 1.53 eV with phenylsulfonic acid groups and realized a transistor and high-performance near-infrared photodetector array for a flexible vision sensory-neuromorphic system. The phenylsulfonic acid groups modified Ti₃C₂T_x MXene (S-Ti₃C₂T_x)-based flexible photodetector has a maximum responsivity of 8.50×10² A W⁻¹ and a detectivity of 3.69×10¹¹ Jones under 1064 nm laser irradiation. Moreover, the fabricated flexible vision sensory-neuromorphic system for image recognition realizes a high recognition rate >0.99, leading to great potential in the field of biological visual simulation and biomimetic eye. Besides conventional devices with Au as the conductive electrodes, all Ti₃C₂T_x MXene-based devices are also fabricated with S-Ti₃C₂T_x as the photosensitive material and unmodified Ti₃C₂T_x as the conductive electrodes, exhibiting comparable optoelectronic performances.     

2D Titanium Carbide (MXene) Based Films: Expanding the Frontier of Functional Film Materials

2D titanium carbide (Ti₃C₂T_x) MXene films, with their well-defined microstructures and chemical functionality, provide a macroscale use of nano-sized Ti₃C₂T_x flakes. Ti₃C₂T_x films have attractive physicochemical properties favorable for device design, such as high electrical conductivity (up to 20 000 S cm^–1), impressive volumetric capacitance (1500 F cm^–3), strong in-plane mechanical strength (up to 570 MPa), and a high degree of flexibility. Here, the appealing features of Ti₃C₂T_x-based films enabled by the layer-to-layer arrangement of nanosheets are reviewed. We devote attention to the key strategies for actualizing desirable characteristics in Ti₃C₂T_x-based functional films, such as high and tunable electrical conductivity, outstanding mechanical properties, enhanced oxidation-resistance and shelf life, hydrophilicity/hydrophobicity, adjustable porosity, and convenient processability. This review further discusses fundamental aspects and advances in the applications of Ti₃C₂T_x-based films with a focus on illuminating the relationship between the structural features and the resulting performances for target applications. Finally, the challenges and opportunities in terms of future research, development, and applications of Ti₃C₂T_x-based films are suggested. A comprehensive understanding of these competitive features and challenges shall provide guidelines and inspiration for the further development of Ti₃C₂T_x-based functional films, and contribute to the advances in MXene technology.     

Synergistic Effect of Photothermal Conversion in MXene/Au@Cu2−xS Hybrids for Efficient Solar Water Evaporation

A three-plasmon hybrid, in which core–shell Au@Cu_2−xS hybrids are bonded with ultrathin Ti₃C₂T_x MXene, is prepared for high-efficiency photothermal conversion and membrane-based solar water evaporation for the first time. The MXene/Au nanorod@Cu_2−xS hybrids display excellent photothermal conversion efficiency under irradiation of an 808 laser, causing by the three-plasmon-induced synergistic plasmonic absorption and heating effects as well as the multichannel charge transfer between the components. Then, Au nanosphere@Cu_2−xS and Au nanorod@Cu_2−xS hybrids are mixed and combined with MXene to serve as the membrane material, which shows excellent light absorption ranging from ultraviolet to near-infrared region. By transferring the membrane materials on a hydrophilic cotton piece, the as-prepared photothermal membrane displays a high evaporation rate of 2.023 kg m⁻² h⁻¹ and light-to-heat conversion efficiency of 96.1% under 1-sun irradiation due to the synergistic photothermal conversion and over 96% of solar light absorption efficiency. Furthermore, a home-made solar evaporation device enabling automatic inflow of untreated water and outflow of evaporated water is designed based on the principles of liquid pressure and connectors. The seawater desalination and sewage treatment experiments performed on the device and membrane indicate the great potential in solar-light-driven water purification and drinkable water generation.     

Engineering the Interlayer Spacing by Pre-Intercalation for High Performance Supercapacitor MXene Electrodes in Room Temperature Ionic Liquid

MXenes exhibit excellent capacitance at high scan rates in sulfuric acid aqueous electrolytes, but the narrow potential window of aqueous electrolytes limits the energy density. Organic electrolytes and room-temperature ionic liquids (RTILs) can provide higher potential windows, leading to higher energy density. The large cation size of RTIL hinders its intercalation in-between the layers of MXene limiting the specific capacitance in comparison to aqueous electrolytes. In this work, different chain lengths alkylammonium (AA) cations are intercalated into Ti₃C₂T_x, producing variation of MXene interlayer spacings (d-spacing). AA-cation-intercalated Ti₃C₂T_x (AA-Ti₃C₂), exhibits higher specific capacitances, and cycling stabilities than pristine Ti₃C₂T_x in 1 m 1-ethly-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMIMTFSI) in acetonitrile and neat EMIMTFSI RTIL electrolytes. Pre-intercalated MXene with an interlayer spacing of ≈2.2 nm, can deliver a large specific capacitance of 257 F g⁻¹ (1428 mF cm⁻² and 492 F cm⁻³) in neat EMIMTFSI electrolyte leading to high energy density. Quasi elastic neutron scattering and electrochemical impedance spectroscopy are used to study the dynamics of confined RTIL in pre-intercalated MXene. Molecular dynamics simulations suggest significant differences in the structures of RTIL ions and AA cations inside the Ti₃C₂T_x interlayer, providing insights into the differences in the observed electrochemical behavior.     

High Linearity,Low Hysteresis Ti3C2Tx MXene/AgNW/Liquid Metal Self-Healing Strain Sensor Modulated by Dynamic Disulfide and Hydrogen Bonds

Flexible wearable strain sensors have received extensive attention in human–computer interaction, soft robotics, and human health monitoring. Despite significant efforts in developing stretchable electronic materials and structures, developing flexible strain sensors with stable interfaces and low hysteresis remains a challenge. Herein, Ti₃C₂T_x MXene/AgNWs/liquid metal strain sensors (MAL strain sensor) with self-healing function are developed by exploiting the strong interactions between Ti₃C₂T_x MXene/AgNWs/LM and the disulfide and hydrogen bonds inside the self-healing poly(dimethylsiloxane) elastomers. AgNWs lap the Ti₃C₂T_x MXene sheets, and the LM acts as a bridge to increase the lap between Ti₃C₂T_x MXene and AgNWs, thereby improving the interface interaction between them and reducing hysteresis. The MAL strain sensor can simultaneously achieve high sensitivity (gauge factor for up to 3.22), high linearity (R² = 0.98157), a wide range of detection (e.g., 1%–300%), a fast response time (145 ms), excellent repeatability, and stability.In addition, the MAL strain sensor before and after self-healing is combined with a small fish and an electrothermally driven soft robot, respectively, allowing real-time monitoring of the swinging tail of the small fish and the crawling of the soft robot by resistance changes.     

Flexible Ti3C2Tx@Al electrodes with Ultrahigh Areal Capacitance: In Situ Regulation of Interlayer Conductivity and Spacing

Although Ti₃C₂ MXene has shown great potential in energy storage field, poor conductivity and restacking between MXene flakes seriously hinders the maximization of its capacitance. Herein, a new strategy to solve the problems is developed. Gallery Al atoms in Ti₃AlC₂ are partially removed by simple hydrothermal etching to get Ti₃C₂T_x reserving appropriate Al interlayers (Ti₃C₂T_x@Al). Ti₃C₂T_x@Al keeps stable layered structure rather than isolated Ti₃C₂T_x flakes, which avoids flake restacking. The removal of partial Al frees up space for easy electrolyte infiltration while the reserved Al as “electron bridges” ensures high interlayer conductivity. As a result, the areal capacitance reaches up to 1087 mF cm^?2 at 1 mA cm^?2 and over 95% capacitance is maintained after 6000 cycles. The all‐solid‐state supercapacitor (ASSS) based on Ti₃C₂T_x@Al delivers a high capacitance of 242.3 mF cm^?2 at 1 mV s^?1 and exhibits stable performance at different bending states. Two ASSSs in tandem can light up a light‐emitting diode under the planar or wrapping around an arm. The established strategy provides a new avenue to improve capacitance performances of MXenes.     

Triple Interface Optimization of Ru-based Electrocatalyst with Enhanced Activity and Stability for Hydrogen Evolution Reaction

A challenging task is to promote Ru atom economy and simultaneously alleviate Ru dissolution during the hydrogen evolution reaction (HER) process. Herein, Ru nanograins (≈1.7 nm in size) uniformly grown on 1T-MoS₂ lace-decorated Ti₃C₂T_x MXene sheets (Ru@1T-MoS₂-MXene) are successfully synthesized with three types of interfaces (Ru/MoS₂, Ru/MXene, and MoS₂/MXene). It gives high mass activity of 0.79 mA µg_Ru⁻¹ at an overpotential of 100 mV, which is ≈36 times that of Ru NPs. It also has a much smaller Ru dissolution rate (9 ng h⁻¹), accounting for 22% of the rate for Ru NPs. Electrochemical tests, scanning electrochemical microscopy measurements combined with DFT calculations disclose the role of triple interface optimization in improved activity and stability. First, 2D MoS₂ and MXene can well disperse and stabilize Ru grains, giving larger electrochemical active area. Then, Ru/MoS₂ interfaces weakening H^* adsorption energy and Ru/MXene interfaces enhancing electrical conductivity, can efficiently improve the activity. Next, MoS₂/MXene interfaces can protect MXene sheet edges from oxidation and keep 1T-MoS₂ phase stability during the long-term catalytic process. Meanwhile, Ru@1T-MoS₂-MXene also displays superior activity and stability in neutral and alkaline media. This work provides a multiple-interface optimization route to develop high-efficiency and durable pH-universal Ru-based HER electrocatalysts.     

Stamping of Flexible,Coplanar Micro‐Supercapacitors Using MXene Inks

The fast growth of portable smart electronics and internet of things have greatly stimulated the demand for miniaturized energy storage devices. Micro‐supercapacitors (MSCs), which can provide high power density and a long lifetime, are ideal stand‐alone power sources for smart microelectronics. However, relatively few MSCs exhibit both high areal and volumetric capacitance. Here rapid production of flexible MSCs is demonstrated through a scalable, low‐cost stamping strategy. Combining 3D‐printed stamps with arbitrary shapes and 2D titanium carbide or carbonitride inks (Ti₃C₂T_x and Ti₃CNT_x, respectively, known as MXenes), flexible all‐MXene MSCs with controlled architectures are produced. The interdigitated Ti₃C₂T_x MSC exhibits high areal capacitance: 61 mF cm^?2 at 25 µA cm^?2 and 50 mF cm^?2 as the current density increases by 32 fold. The Ti₃C₂T_x MSCs also showcase capacitive charge storage properties, good cycling lifetime, high energy and power densities, etc. The production of such high‐performance Ti₃C₂T_x MSCs can be easily scaled up by designing pad or cylindrical stamps, followed by a cold rolling process. Collectively, the rapid, efficient production of flexible all‐MXene MSCs with state‐of‐the‐art performance opens new exciting opportunities for future applications in wearable and portable electronics.     

Pristine Titanium Carbide MXene Films with Environmentally Stable Conductivity and Superior Mechanical Strength

2D titanium carbide (Ti₃C₂T_x MXene) has potential application in flexible/transparent conductors because of its metallic conductivity and solution processability. However, solution‐processed Ti₃C₂T_x films suffer from poor hydration stability and mechanical performance that stem from the presence of intercalants, which are unavoidably introduced during the preparation of Ti₃C₂T_x suspension. A proton acid colloidal processing approach is developed to remove the extrinsic intercalants in Ti₃C₂T_x film materials, producing pristine Ti₃C₂T_x films with significantly enhanced conductivity, mechanical strength, and environmental stability. Typically, pristine Ti₃C₂T_x films show more than twofold higher conductivity (10 400 S cm^?1 vs 4620 S cm^?1) and up to 11‐ and 32‐times higher strength and strain energy at failure (112 MPa, 1,480 kJ m^?3, vs 10 MPa, 45 kJ m^?3) than films prepared without proton acid processing. Simultaneously, the conductivity and mechanical integrity of pristine films are also largely retained during the long‐term storage in H₂O/O₂ environment. The improvement in mechanical performance and conductivity is originated from the intrinsic strong interaction between Ti₃C₂T_x layers, and the absence of extrinsic intercalants makes pristine Ti₃C₂T_x films stable in humidity by blocking the intercalation of H₂O/O₂. This method makes the material more competitive for real‐world applications such as electromagnetic interference shielding.     

Substitutionally Dispersed High-Oxidation CoOx Clusters in the Lattice of Rutile TiO2 Triggering Efficient Co?Ti Cooperative Catalytic Centers for Oxygen Evolution Reactions

The development of economical, highly active, and robust electrocatalysts for oxygen evolution reaction (OER) is one of the major obstacles for producing affordable water splitting systems and metal-air batteries. Herein, it is reported that the subnanometric CoO_x clusters with high oxidation state substitutionally dispersed in the lattice of rutile TiO₂ support (Co-TiO₂) can be prepared by a thermally induced phase segregation process. Owing to the strong interaction of CoO_x clusters and TiO₂ support, Co-TiO₂ exhibits both excellent intrinsic activity and durability for OER. The turnover frequency of Co-TiO₂ is up to 3.250 s⁻¹ at overpotentials of 350 mV; this value is one of the highest in terms of OER performance among the current Co-based active materials under similar testing conditions; moreover, the OER current density loss is only 6.5% at a constant overpotential of 400 mV for 30 000 s, which is superior to the benchmark Co₃O₄ and RuO₂ catalysts. Mechanism analysis demonstrates that charge transfer occurs between Co sites and their neighboring Ti atoms, triggering the efficient Co Ti cooperative catalytic centers, in which OH* and O* are preferred to be adsorbed on the bridging sites of Co and Ti with favorable adsorption energy, inducing a lower energy barrier for O₂ generation.     

Advanced High Entropy Perovskite Oxide Electrocatalyst for Oxygen Evolution Reaction

A new type of lanthanum-based high entropy perovskite oxide (HEPO) electrocatalyst for the oxygen evolution reaction is reported. The B-site lattices in the HEPO consist of five consecutive first-row transition metals, including Cr, Mn, Fe, Co, and Ni. Equimolar and five non-equimolar HEPO electrocatalysts are studied for their OER electrocatalytic performance. In the five non-equimolar HEPOs, the concentration of one of the five transition metals is doubled in individual samples. The performances of all the HEPOs outperform the single perovskite oxides. The optimized La(CrMnFeCo₂Ni)O₃ HEPO exhibits an outstanding OER overpotential of 325 mV at a current density of 10 mA cm⁻² and excellent electrochemical stability after 50 h of testing.     

Nonoxidized MXene Quantum Dots Prepared by Microexplosion Method for Cancer Catalytic Therapy

Nanocatalysts based on Fenton or Fenton‐like reactions for amplification of intracellular oxidative stress has become a frontier research area of tumor precise therapy. However, the major translational challenges are low catalytic efficiency, poor biocompatibility, and even potential toxicities. Here, a Ti‐based material with excellent biocompatibility is proposed for cancer treatment. The nonoxidized MXene‐Ti₃C₂T_x quantum dots (NMQDs‐Ti₃C₂T_x) are successfully prepared by a self‐designed microexplosion method. Surprisingly, it has an apparent inhibitory and killing effect on cancer cells, and excellent biocompatibility with normal cells. Moreover, the suppression rate of NMQDs‐Ti₃C₂T_x on xenograft tumor models can reach 91.9% without damaging normal tissues. Mechanistically, the Ti³⁺ of NMQDs‐Ti₃C₂T_x can react with H₂O₂ in the tumor microenvironment and high‐efficiently produce excessive toxic hydroxyl radicals to increase tumor microvascular permeability to synergistically kill cancer cells. This work should pave the way for tumor catalytic therapy applications of Ti‐based material as a promising and safer route.     

Constructing Flexible Film Electrode with Porous Layered Structure by MXene/SWCNTs/PANI Ternary Composite for Efficient Low-Grade Thermal Energy Harvest

Thermal energy, constituting the majority of the energy lost through various inefficiencies, is abundant and ubiquitous. With thermogalvanic effect, thermocells (TECs) can directly convert thermal energy into electricity without producing vibration, noise or other waste emissions. This work presents a rational design of flexible film electrodes constructed on a ternary composite of Ti₃C₂T_x MXene (T_x represents surface terminations), polyaniline (PANI) and single-wall carbon nanotubes for TECs, which exhibit notably enhanced thermoelectrochemical performance compared to the widely adopted noble platinum electrodes. The ternary composite electrodes form a porous layered structure with a large electrochemical-active surface area. Experiment and simulation results reveal that synergistic effects of Ti₃C₂T_x and PANI are induced for promoting both mass and charge transport at the electrolyte-electrode interface, resulting in a TEC with an output power of 13.15 µW cm⁻² at the ΔT of 40 K. The TEC also shows a rapid response to the small temperature difference between the human body and the ambient, demonstrating high potential in harvesting low-grade heat to power small electronics.