Ti3C2Tx MXene Research Articles

High-Performance Ideal Bandgap Sn-Pb Mixed Perovskite Solar Cells Achieved by MXene Passivation.

Ideal bandgap (1.3-1.4eV) Sn-Pb mixed perovskite solar cells (PSC) hold the maximum theoretical efficiency given by the Shockley-Queisser limit. However, achieving high efficiency and stable Sn-Pb mixed PSCs remains challenging. Here, piperazine-1,4-diium tetrafluoroborate (PDT) is introduced as spacer for bottom interface modification of ideal bandgap Sn-Pb mixed perovskite. This spacer enhances the quality of the upper perovskite layer and forms better energy band alignment, leading to enhanced charge extraction at the hole transport layer (HTL)/perovskite interface. Then, 2D Ti3C2Tx MXene is incorporated for surface treatment of perovskite, resulting in reduced surface trap density and enhanced interfacial electron transfer. The combinations of double-sided treatment afford the ideal bandgap PSC with a high efficiency of 20.45% along with improved environment stability. This work provides a feasible guideline to prepare high-performance and stable ideal-bandgap PSCs.

Tailoring surface terminals of Ti3C2Tx MXene microgels via interlayer domain-confined polyphosphate ammonium for flexible supercapacitor applications

The MXene material shows potential for flexible energy storage devices due to its high pseudocapacitance and mechanical flexibility. However, MXene nanosheet self-stacking and –F terminal functional groups can hinder active site and ion dynamics, thus affecting the energy storage performance. Herein, we present an interlayer domain-confined strategy that involves the introduction and crosslinking of ammonium polyphosphate (APP) confined to the interlayer of Ti3C2Tx MXene sheets, which induces gelation of the MXene to form a 3D network structure and enlarge their interlayer spacing. And then the cross-linked APP is converted into nitrogen and phosphorus terminals on Ti3C2Tx MXene via thermal treatment. The nitrogen terminals in the form of the pyrrole nitrogen and pyridine nitrogen, and phosphorus terminals of P–O bonds enhance the activity of the redox reaction and the dynamics of the ions, resulting in the boosted energy storage capacity of MXene. The density functional theory (DFT) calculations reveal that nitrogen-phosphorus co-doping modulates the surface electronic states of MXene and contributes to the increase of the electrical conductivity of Ti3C2Tx MXene. As a supercapacitor electrode, Ti3C2Tx MXene with N/P terminals exhibits a higher specific capacitance of 597.8 F/g (1777F cm−3) than the raw Ti3C2Tx MXene (384 F/g). In addition, the quasi-solid state flexible symmetric supercapacitor assembled by Ti3C2Tx MXene with N/P terminals can achieve an energy density of 12.5 Wh kg−1 at a power density of 250 W kg−1. Therefore, this work provides a new strategy for terminal modification of MXene and high-performance MXene supercapacitors.

Unveiled mechanism of prolonged stability of Zn anode coated with two‐dimensional nanomaterial protective layers toward high‐performance aqueous Zn ion batteries

AbstractRechargeable aqueous zinc (Zn) ion batteries (AZIBs) are gaining popularity in large‐scale energy storage due to their low cost, high safety, and environmental friendliness; however, dendrite growth and side reactions in Zn metal anodes limit their practical applications. Additionally, the difficulty of developing successful passivation of Zn anodes, combined with large‐area coating of protective layers, remains a major limitation to the commercialization of AZIBs. Here, we introduce two‐dimensional (2D) nanomaterials including MoS2, h‐BN, and Ti3C2Tx MXene as protective layers for Zn anodes, created on a Zn surface using a scalable, large‐area spray‐coating process. Examinations of electrochemical performance‐related material characterizations revealed that a specific type of 2D material with an optimal thickness prevents vertical growth of Zn dendrites, as well as side reactions including hydrogen evolution and corrosion, resulting in stable device operation with minimal overpotential and extended life, even under harsh measurement conditions. The highly stable MoS2@Zn anode allowed the MoS2@Zn//MnO2 full cell to achieve significantly more stable capacity retention, compared with the bare Zn//MnO2 cell. Our versatile and scalable solution‐based coating technique for easily forming large‐area 2D protective layers on Zn anodes offers new insights concerning improvements to AZIB reliability and performance.image

Structurally integrated Ti3C2Tx MXene/cotton fabric electrodes for supercapacitor applications

This study investigates the electrochemical performance of Ti3C2Tx MXene-coated cotton fabric electrodes for supercapacitor applications. The sediment and supernatant parts of synthesized Ti3C2Tx MXene were applied onto cotton substrates through a drop-casting technique at various concentrations to explore the influence of MXene dispersion density on the structural, morphological, and electrochemical properties of the fabric electrodes. Findings indicate that the lower-concentration dispersions not only improve the structural integrity of the coatings but also enhance their electrochemical functionality. The fabric electrodes fabricated from MXene supernatant exhibited significantly lower electrical resistance (7.3 Ω sq−1) and higher specific capacitance, reaching 488 F g−1 at a current density of 0.5 A g−1. The study demonstrates the potential of MXene-coated fabrics as adaptable and efficient energy solutions for wearable technologies, highlighting that tuning the concentration and post-synthesis parameters of MXene dispersions can effectively alter their electrochemical properties.

Highly capacitive MXene film by incorporating poly(3,4-ethylenedioxythiophene) hollow spheres prepared through an interfacial oxidation polymerization

Sheets stacking of Ti3C2Tx MXene dramatically reduces the ion-accessible sites and brings a sluggish reaction kinetics. While introducing transitional metal oxides or polymers in the MXene films could partially alleviate such issue, their enhanced performances are realized at the expense of electrode conductivity or cycling stability. Herein, we report an alternative spacer of conductive poly(3,4-ethylenedioxythiophene) (PEDOT) hollow spheres (HSs) which are fabricated by a facile template-assisted interfacial polymerization. The Fe3+ ions electrostatically adsorbed on the –SO3H groups of the sulfonated polystyrene spheres (S-PS) initiate the polymerization of uniform PEDOT shell, yielding uniform PEDOT HSs after dissolving the S-PS core. Introducing these PEDOT HSs in the MXene film generates the highly flexible MXene-PEDOT (MP) films featuring hierarchically porous network and high conductivity (283 S cm−1). Consequently, specific capacitance of 218 F g−1 at 3 mV s–1, along with a forty-folds decrease in relaxation time constant (1.0 vs 39.8 s) has been achieved. Moreover, the MP film also exhibits nearly thickness-independent capacitive performances with film thickness in the range of 10–46 μm. A maximal energy density of 21.2 μWh cm−2 at 1015 μW cm−2 together with 92 % capacitance retention over 5000 cycles are achieved for the MP-based solid-state supercapacitor. The intrinsic high conductivity, excellent mechanical flexibility and good structure integrity are responsible for such outstanding electrochemical behaviors.

Point-of-care testing device platform for the determinationof creatinine on an enzyme@CS/PB/MXene@AuNP-based screen-printed carbon electrode.

Screen-printed carbon electrodes (SPCE) functionalized with MXene-based three-dimensional nanomaterials are reportedfor rapid determinationof creatinine. Ti3C2TX MXene with in situ reduced AuNPs (MXene@AuNP) were used as a coreactant accelerator for efficient immobilization of enzymes. Creatinine could be oxidized by chitosan-embedded creatinine amidohydrolase, creatine amidinohydrolase, or sarcosine oxidase to generate H2O2, which could be electrochemically detected enhanced by Prussian blue (PB). The enzyme@CS/PB/MXene@AuNP/SPCE detected creatinine within the range 0.03-4.0mM, with a limit of detection of 0.01mM, with anaverage recovery of 96.8-103.7%. This indicates that the proposed biosensor is capable of detecting creatinine in a short amount of time (4min) within a ± 5% percentage error, in contrast with the standard clinical colorimetric method. With this approach, reproducible and stable electrochemical responses could be achieved for determinationof creatinine in serum, urine, or saliva. These results demonstrated its potential for deployment in resource-limited settings for early diagnosis and tracking the progression of chronic kidney disease (CKD).

Interface engineering based NiCoMoO4/Ti3C2Tx MXene heterostructure for high-performance flexible supercapacitors

The advancement of interface engineering has demonstrated remarkable efficacy in overcoming the primary impediment associated with sluggish reaction kinetics in supercapacitor electrodes. In this investigation, we employed a facile co-precipitation method to synthesize NiCoMoO4/MXene heterostructures utilizing Ti3C2Tx MXene nanosheets as carriers. This heterostructure inhibits the restacking of MXene nanosheets and simultaneously enhances the exposure of electrochemically active sites in NiCoMoO4 nanorods, thereby mitigating the reduction in specific capacitance resulting from volumetric fluctuations. The NiCoMoO4/MXene electrode, possessing pseudo-capacitance properties, demonstrates an impressive level of specific capacitance, exceptional performance across various charging rates, and consistent behavior throughout repeated cycles. By optimizing the mass ratio, this electrode achieves a specific capacity of 1900 F/g under a current density of 1 A/g. Even after enduring 10,000 cycles at a significantly higher current density of 5 A/g, it still maintains an impressive retention rate of 94.73 %. Our density functional theory (DFT) calculations indicate that the enhanced electrochemical performance can be attributed to the improved electronic coupling within the NiCoMoO4/MXene heterostructure. The integration of NiCoMoO4/MXene cathode and activated carbon (AC) anode with an alkaline gel electrolyte containing potassium ferricyanide in flexible quasi-solid-state supercapacitors (FSSCs) results in exceptional electrochemical performance and flexibility. These FSSCs demonstrate a maximum energy density of 72.89 Wh kg−1 at a power density of 850 W kg−1, while maintaining an impressive power output of 16,780 W kg−1 with an energy density of 37.28 Wh kg−1. Based on these outstanding properties, it is evident that the NiCoMoO4/MXene heterojunction possesses significant advantages as electrode material for supercapacitors, and the fabricated FSSCs devices pave a new pathway for flexible electronic devices.

An electrochemical aptamer-sensing strategy based on a Ti3C2Tx MXene synergistic Ti-MOF amplification signal for highly sensitive detection of zearalenone

A refined electrochemical aptamer sensing technique using PEI@Ti-MOF@Ti3C2Tx-MXene was developed for the sensitive detection of ZEN in food samples. A titanium-based metal-organic skeleton (NH2-MIL-125) was synthesized in situ using 2-aminoterephthalic acid as the organic ligand and tetrabutyl titanate as the metal center, followed by the simultaneous hybridization of Ti3C2Tx-MXene to synthesize a Ti-MOF@Ti3C2Tx-MXene composite material. These composites were subsequently functionalized with PEI and covalently linked to form a sensing platform on gold electrodes. Integrating a metal-organic framework (MOF) with MXene materials not only improved the electrochemical properties compared to those of individual elements but also decreased the stacking effect and increased the number of binding sites for the aptamer. The limit of detection (LOD) of this sensor was 1.64 fg mL−1. Additionally, the sensor could efficaciously detect ZEN in cornmeal and beer samples, exhibiting outstanding stability, reproducibility, and selectivity. This highlighted its effectiveness in applications in quality supervision and food safety.

Elucidating the Interactions between Different Transition Metal Cations and Ti3C2Tx MXene through Intercalation Method for Electrochemical Applications

MXenes, are a family of two-dimensional (2D) transition metal carbides, nitrides and/ or carbonitrides.[1] The intercalation of different metal cations and organic molecules into MXene for tuning MXenes’ electronic and electrochemical properties have been widely reported.[2] [3] [4] However, transition metals (TMs) which have distinct electrochemical behaviors[5] [6] have not been explored in the literature of MXenes’ intercalation. Therefore, we herein compared the intercalation effects of different TM cations on Ti3C2Tx, for offering a general insight on the influences of multi-valent, redox-active TMs on MXenes. In particular, the changes on the physiochemical and electrochemical properties of MXenes were investigated using different in-situ and ex-situ methods, for a better understanding on the interfacial interactions of TM cations and MXenes in the confined environment of MXenes’ multilayer structures. This work serves as a foundation for the fine-tuning of MXenes’ properties by utilizing a variety of TM cations intercalation for different electrochemical systems.[1] B. Anasori, M. R. Lukatskaya, Y. Gogotsi, Nature Reviews Materials 2017, 2, 16098.[2] M. R. Lukatskaya, O. Mashtalir, E. Ren Chang, Y. Dall’Agnese, P. Rozier, L. Taberna Pierre, M. Naguib, P. Simon, M.W. Barsoum, Y. Gogotsi, Science 2013, 341, 1502-1505.[3] J. Li, H. Wang, X. Xiao, Energy & Environmental Materials 2020, 3, 306-322[4] M. Ghidiu, S. Kota, J. Halim, A. W. Sherwood, N. Nedfors, J. Rosen, V. N. Mochalin, M. W. Barsoum, Chemistry of Materials 2017, 29, 1099-1106.[5] D. Göhl, H. Rueß, M. Pander, A. R. Zeradjanin, K. J. J. Mayrhofer, J. M. Schneider, A. Erbe, M. Ledendecker, Journal of The Electrochemical Society 2020, 167, 021501.[6] M. Esmaeilirad, A. Baskin, A. Kondori, A. Sanz-Matias, J. Qian, B. Song, M. Tamadoni Saray, K. Kucuk, A. R. Belmonte, P. N. M. Delgado, J. Park, R. Azari, C. U. Segre, R. Shahbazian-Yassar, D. Prendergast, M. Asadi, Nature Communications 2021, 12, 5067.

MXene-Polydopamine-antiCEACAM1 Antibody Complex as a Strategy for Targeted Ablation of Melanoma.

Photothermal therapy (PTT) is a method for eradicating tumor tissues through the use of photothermal materials and photosensitizing agents that absorb light energy from laser sources and convert it into heat, which selectively targets and destroys cancer cells while sparing healthy tissue. MXenes have been intensively investigated as photosensitizing agents for PTT. However, achieving the selectivity of MXenes to the tumor cells remains a challenge. Specific antibodies (Ab) against tumor antigens can achieve homing of the photosensitizing agents toward tumor cells, but their immobilization on MXene received little attention. Here, we offer a strategy for the selective ablation of melanoma cells using MXene-polydopamine-antiCEACAM1 Ab complexes. We coated Ti3C2Tx MXene with polydopamine (PDA), a natural compound that attaches Ab to the MXene surface, followed by conjugation with an anti-CEACAM1 Ab. Our experiments confirm the biocompatibility of the Ti3C2Tx-PDA and Ti3C2Tx-PDA-antiCEACAM1 Ab complexes across various cell types. We also established a protocol for the selective ablation of CEACAM1-positive melanoma cells using near-infrared irradiation. The obtained complexes exhibit high selectivity and efficiency in targeting and eliminating CEACAM1-positive melanoma cells while sparing CEACAM1-negative cells. These results demonstrate the potential of MXene-PDA-Ab complexes for cancer therapy. They underline the critical role of targeted therapies in oncology, offering a promising avenue for the precise and safe treatment of melanoma and possibly other cancers characterized by specific biomarkers. Future research will aim to refine these complexes for clinical use, paving the way for new strategies for cancer treatment.

Harnessing the Power of Nano‐Ferroelectrics: BaTiO3/MXene (Ti3C2Tx) Composites for Enhanced Lithium Storage

Abstract2D Ti3C2Tx MXene is a desirable electrode material for advanced lithium‐ion batteries (LIBs) in the pursuit of high energy and power densities, owing to its extensive reactive area and surface‐induced pseudo‐capacitance. Here, a novel synergistic strategy for fortifying lithium storage capability is first proposed, by in‐situ anchoring BaTiO3 ferroelectric nanoparticles on few‐layered Ti3C2Tx nanosheets (BT/f‐Ti3C2Tx) using a hydrothermal method. The uniform BaTiO3 nanoparticles effectively prevent the restacking of Ti3C2Tx nanosheets, successfully deplete metastable Ti atoms, and intriguingly form a thin and well‐adhered solid electrolyte interface layer, enhancing the aggregation‐resistant, oxidation‐resistant, and electrochemical properties of Ti3C2Tx. Simultaneously, the internal electric fields, originating from the spontaneous polarization of BaTiO3 ferroelectric nanoparticles, can augment the adsorption of Li+, boosting the lithium storage capacity and reaction kinetics. The resulting composite electrode displays a remarkable charge capacity of 84 mAh g−1 at 10 A g−1, almost five times that of pristine Ti3C2Tx electrode. The excellent rate performance and cyclability make BT/f‐Ti3C2Tx composites highly attractive for LIBs. Furthermore, this synthetic approach presented here is scalable and can be extended to other Ti‐based materials. This strategy is expected to underscore the considerable potential of ferroelectric composites for integration into high‐performance LIBs.

Synergizing Electron and Ion Transports of Ti3C2TX MXene Fiber via Dot‐Sheet Heterostructure and Covalent Ti─C─Ti Cross‐Linking for Efficient Charge Storage and Thermal Management

AbstractTi3C2TX MXene with the merits of metallic conductivity, superhigh volumetric capacitance, and efficient absorption of the electromagnetic wave is considered a promising building block for fiber fabrication; nevertheless, the simultaneous improvement in electrochemical charge storage and electrical conductivity/thermal management is seldom achieved for MXene‐based fibers due to the contradictory in material design. Typically, aligned and densified packing of MXene fibers is highly desired for an enhanced intra‐/inter‐flake electron transport; however, the narrowed inter‐layer spacing restricts the kinetics of ion diffusion (the intercalation/de‐intercalation of electrolyte ions) and diminishes the accessible active sites for charge storage. Herein, the electron and ion transports of Ti3C2TX MXene fiber are synergized via a unique dot‐sheet heterostructure covalently bonded by Ti─C─Ti which provides the optimal inter‐layer spacing for rapid ion diffusion and enhances the intra‐/inter‐flake cross‐linking for fast electron transport. As a result, the obtained fiber offers an improved conductivity of 2405 S cm−1, a desirable capacitance of 1597 F cm−3, an impressive energy density of 19.8 mWh cm−3 for the assembled supercapacitor, superior Joule heating performance, and a photo‐thermal temperature. These remarkable attributes enable their practical applications in energy‐supply scenarios, such as powering LEDs and wearable thermal management.

2D/2D Heterojunction of Cobalt‐Iron Selenide Nanolamellas/MXene for Enhanced Electrocatalytic Hydrogen Evolution

AbstractElectrochemical water splitting is considered to be a green and flexible strategy for the mass production of hydrogen fuel, while the high cost and insufficent activity of current cathode catalysts severely suffocate the widespread thriving of hydrogen economy. Herein, we present a bottom‐up assembly strategy to the controllable construction of 2D/2D heterojunctions built from cobalt‐iron selenide nanolamellas and Ti3C2Tx MXene nanosheets. This unique architectural design gives the resulting CoyFe1‐ySe2/Ti3C2Tx catalysts a series of interesting structural advantages, such as 2D/2D heterostructure, large active surface areas, modulated electronic structure, uniform CoyFe1‐ySe2 dispersion, and good electron conductivity, thereby leading to strong synergistic coupling effects. As a consequence, the optimized Co0.7Fe0.3Se2/Ti3C2Tx electrocatalyst with an appropriate Co/Fe ratio possesses unusual hydrogen evolution properties in terms of a low overpotential of 69 mV at 10 mA cm−2, a small Tafel slope of 51 mV dec−1 and reliable long‐term durability, which are more competitive than those of bare Ti3C2Tx, FeSe2 and CoSe catalysts.

Fast Responsive and High-Strain Electro-Ionic Soft Actuator Based on the 3D-Structure MXene-EGaIn/MXene Bilayer Composite Electrode.

Electro-ionic soft actuators have garnered significant attention owing to their promising applications in flexible electronics, wearable devices, and soft robotics. However, achieving high actuation performance (large bending strain and fast response time) of these soft actuators under low voltage has been challenging due to issues related to ion diffusion and accumulation. In this study, an electro-ionic soft actuator is fabricated using Ti3C2Tx MXene and eutectic gallium-indium (EGaIn) composite material as the bilayer electrode and methylammonium formate/1-ethyl-3-methylimidazolium tetrafluoroborate/poly(vinylidene fluoride) (MAF-EMIMBF4/PVDF) as the ionic liquid-type electrolyte. The research results indicate that the prepared soft actuator exhibits excellent actuation performance with a peak-to-peak displacement of 35 mm and a bending strain of 0.69% (a peak-to-peak strain of 1.38%) under a low voltage (3 V). The electro-ionic soft actuator shows a wide frequency range (0.1-10 Hz), fast response time (0.35 s), and a rise time of 7.5 s. Furthermore, it demonstrates good cyclic durability, with a retention rate of 92.5% of its performance for 10 000 cycles. These excellent performances are attributed to the 3D structure of the Ti3C2Tx-EGaIn/Ti3C2Tx bilayer composite electrode, as well as the characteristics of the low viscosity, high conductivity, small ion volume, and larger volume difference between cations and anions in MAF ionic liquid. The high-performance electro-ionic soft actuator can be used in various fields such as artificial muscles, tactile devices, and soft robots.

γ-Radiation-induced in-situ formation of TiC/MXene nanocomposites for superior electromagnetic wave absorption

The layered structure of two-dimensional transition metal carbides/nitrides (MXenes) is potentially conducive to efficient electromagnetic wave absorption (EWA). However, Ti3C2Tx MXene typically encounters challenges with a narrow effective absorption bandwidth (EAB) due to impedance mismatch caused by its inherent high conductivity. This study employed γ-radiation to induce the in-situ formation of TiC/MXene nanocomposites for EWA. The radiation preparation process is carried out under reducing conditions at ambient temperature and pressure, effectively minimizing the risk of MXene oxidation while preserving its original layered structure. The resultant intercalated structure, featuring in-situ formed TiC nanoparticles embedded within the Ti3C2Tx MXene layers, facilitates the integration of layered conductive networks with abundant spatial gaps and multiple heterojunction interfaces. Leveraging these structural and chemical advantages, the composite demonstrates enhanced EWA capabilities. At a 50 wt% irradiated MXene loading, the material achieves an EAB of 6.08 GHz at 1.55 mm thickness and a minimum reflection loss (RLmin) of −51.1 dB at 3.95 mm. Compared to conventional composite fabrication methods, γ-radiation offers a more environmentally sustainable, efficient, and scalable approach. This research opens up a new avenue for exploiting the MXene family in EWA applications.

Dielectric and thermal conductive properties of differently structured Ti3C2Tx MXene-integrated nanofibrillated cellulose films

The fabrication of nanocellulose-based substrates with high dielectric permittivity and anisotropic thermal conductivity to replace synthetic thermoplastics in flexible organic electronics remains a big challenge. Herein, films were prepared from native (CNF) and carboxylated (TCNF) cellulose nanofibrils, with and without the addition of thermally conductive multi-layered Ti3C2Tx MXene, to examine the impact of polar (− OH, − COOH) surface groups on the film morphological, moisturizing, dielectric, and thermal dissipation properties. The electrostatic repulsion and hydrogen bonding interaction between the hydrophilic surface/terminal groups on CNF/TCNF and MXene was shown to render their self-assembly distribution and organization into morphologically differently structured films, and, consequently, different properties. The pristine CNF film achieved high intrinsic dielectric permittivity (ε' ~ 9), which was further increased to almost ε' ~ 14 by increasing (50 wt%) the MXene content. The well-packed and aligned structure of thinner TCNF films enables the tuning of both the composite’s dielectric permittivity (ε' ~ 6) and through-plane thermal conductivity (K ~ 2.9 W/mK), which increased strongly (ε' ~ 17) at higher MXene loading giving in-plane thermal conductivity of ~ 6.3 W/mK. The air-absorbed moisture ability of the films contributes to heat dissipation by releasing it. The dielectric losses remained below 0.1 in all the composite films, showing their potential for application in electronics.Graphic abstract

Tunable interlayer spacings Ti3C2Tx MXene/Ni/C for enhanced electromagnetic microwave absorption

While two-dimensional lamellar materials, specifically Ti3C2Tx MXenes, have shown great promise as wave-absorbing materials, the precise design of interlayer spacing poses a persistent challenge. In this study, Ti3C2Tx MXene layers with adjustable interlayer spacings were crafted using a straightforward molecular welding technique. Through the incorporation of Ni nanoparticles onto the Ti3C2Tx MXene layers using a combination of simple mechanical stirring and carbonation reactions, we successfully developed Ti3C2Tx MXene/Ni/C composites featuring a distinct lamellar structure. A uniform dispersion of Ni nanoparticles on the surface of the Ti3C2Tx MXene nanosheets was found with some of the nanoparticles intercalated into the layers. The Ti3C2Tx MXene/Ni/C composites exhibited a maximum reflection loss (RL) value of −42.3 dB at 12.3 GHz, accompanied by an impressive effective absorption bandwidth (EAB) of 5.6 GHz. This outstanding absorption performance could be attributed to various factors, including the dielectric loss of the Ti3C2Tx MXene lamellae, reflections and scattering of multiphase heterostructures, the magnetic loss of the Ni nanoparticles, and their synergistic attenuation. Furthermore, Ni nanoparticles with high electrical conductivity induced vortex currents under the alternating influence of electromagnetic waves (EMWs), resulting in a substantial depletion. This study introduces an innovative approach for synthesizing Ti3C2Tx MXene/Ni/C composites with tunable interlayer spacing, showing their potential for applications in microwave absorption (MA).

Ti3C2Tx MXene-mediating near- and long-range electronic effect on atomically dispersed Co for efficient lithium-sulfur batteries

Sluggish sulfur conversion kinetics pose an ongoing challenge in lithium-sulfur batteries (LSBs). Here, we present a solution through far-reaching long-range electronic regulation (LRER) on single-atom active sites. N-doped carbons (Co-NC) are implanted with densely-distributed Co single atoms, and supported on Ti3C2Tx MXene substrates to assemble 3D Co-NC/MXene catalyst. MXene effectively mediates interlayer charge transfer (∼0.70 |e|) contrasted with popular carbon materials (∼0.06 |e|) to produce LRER through surrounding carbon atoms. The synergy of LRER with near-range electronic regulation (NRER) tunes electronic structures, and enhances heterostructural stability, thus provoking desirous catalytic kinetics of Co single atoms in sulfur reduction. Thereby, the Co-NC/MXene/S cathodes exhibit impressive rate performance and excellent cycling stability (only 0.015% capacity decay per cycle over 600 cycles at 4 C) in LSBs, surpassing state-of-the-art sulfur cathodes. This work reveals the importance of LRER for improved catalysis, and provides new guidance to tailor heterostructures to achieve high-efficient catalysts in various process.

Fast Reduction of 4-Nitrophenol and Photoelectrochemical Hydrogen Production by Self-Reduced Bi/Ti3C2Tx/Bi2S3 Nanocomposite: A Combined Experimental and Theoretical Study.

The distinctive properties of 2D MXenes have garnered significant interest across various fields, including wastewater treatment and photo/electro-catalysis. The integration of inexpensive semiconductor nanostructures with 2D MXenes offers a promising strategy for applications such as wastewater treatment and photoelectrochemical hydrogen production. In this study, we employed an in situ hydrothermal method to immobilize 1D Bi2S3 nanorods and self-reduced metallic bismuth nanoparticles (Bi NPs) onto Ti3C2Tx MXene nanosheets, resulting in the formation of a Bi/Bi2S3/Ti3C2Tx (0D/1D/2D) composite catalyst, which demonstrates an outstanding efficacy in both the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) and photoelectrochemical hydrogen production. Remarkably, a 4-NP reduction efficiency of 100% was achieved only in 4 min with a reduction rate of 1.14 min-1, which is outstanding, and it is ∼3.8 times faster than pristine Bi2S3 nanorods (0.3 min-1). Furthermore, the photoelectrochemical assessment reveals that the Bi/Bi2S3/Ti3C2Tx catalyst displays remarkable hydrogen evolution reaction (HER) efficiency in an alkaline electrolyte. It exhibits a significantly lower overpotential and Tafel slope of 73 mV and 84 mV/dec, respectively, compared to pristine Bi2S3 nanorods, which are found to be 129 mV and 145 mV/dec under light illumination. The superior reduction performance of 4-NP and charge transfer mechanism is further investigated through density functional theory (DFT) calculations, alongside validation using various microscopic and spectroscopic techniques. Interestingly, the DFT analysis revealed modifications in the partial density of states of Bi2S3 within the band gap region due to the successful anchoring of Ti3C2Tx nanosheets and metallic Bi NPs, facilitating efficient charge transport and separation across the local junctions. Ultraviolet photoelectron spectroscopy provided insights into band alignment and interfacial charge transfer across the Bi/Bi2S3/Ti3C2Tx junction on a microscopic scale. This work is significant for the development of MXene-based hybrid catalysts, and it provides a deeper understanding of the reduction mechanism of organic pollutants and superior charge transport in the hybrid system for photoelectrochemical hydrogen production.

Electrochemical real-time sensor for the detection of Pb(II) ions based on Ti3C2Tx MXene

Lead ions are especially harmful to human health, causing significant developmental and behavioral abnormalities even at small concentrations. In real-life samples, lead ions are present in mixtures with other metal ions, creating a challenge to detect it selectively at low quantities. To address these challenges, we prepared an electrochemical sensor based on delaminated Ti3C2Tx MXene, which can selectively detect low concentrations of Pb2+ in a solution containing other common metal ions. Cyclic voltammetry was applied as an electrochemical detection method. The proposed reaction mechanism involves a reversible transition between Pb2+ ions and PbO at the MXene-based layer. The sensitivity of the sensor towards Pb2+ ions and a limit of detection were determined. The sensor, as prepared, had a linear response range within 0.15–1.0 μM, with a sensitivity of 26.7 μA/μM and LOD value of 48.7 nM, which meets the requirements set by the World Health Organization.