Ti3C2 Sheets Research Articles

Exploring the Electrochemical Superiority of V2O5/TiO2@Ti3C2-MXene Hybrid Nanostructures for Enhanced Lithium-Ion Battery Performance.

The use of vanadium(V)-based materials as electrode materials in electrochemical energy storage (EES) devices is promising due to their structural and chemical variety, abundance, and low cost. V-based materials with a layered structure and high multielectron transfer in the redox reaction have been actively explored for energy storage. Our current work presents the structural and electrochemical properties of a vanadium-based composite with TiO2@Ti3C2 MXene, referred to as VM. This composite is obtained through the in situ thermal decomposition of the VO2(OH)/Ti3C2mixture, which is achieved by solution mixing and drying. The material structure is confirmed using various characterization tools, which establish an orthorhombic V2O5 nanostructure compositing with nanocrystalline TiO2@Ti3C2. VM with 5 wt % MXene, referred to as VM5, can achieve 460 mAhg-1 at a current density of 0.1 Ag1- and 290 mAhg-1 at 1 Ag1-, with an average coulombic efficiency of 98.5%. The presence of the V2O5/TiO2 (nanocrystals) heterojunction attached with Ti3C2 sheets contributed to reduced charge transfer resistance. The cyclic stability shows a capacity retention of 62% over 500 cycles at 1 Ag1- (4C rate, where 1C equals 0.25 Ag1-) with a 0.22 capacity drop with each cycle. Dunn's approach to examining the charge storage mechanism demonstrates 72% contribution of the surface-dominant capacitive process and 28% of the diffusion-controlled intercalation process at 0.4 mVs-1, suggesting a potential high-performance pseudocapacitive hybrid electrode material for lithium-ion batteries.

Coating of ThO2 (111) surface with two–dimensional sheets for potential corrosion protection

ThO2 is an important nuclear fuel that could be used in molten salt reactors, and its corrosion behaviors and anticorrosion mechanisms should be in–depth understood. More emerging two–dimensional (2D) sheets show potentially great corrosion resistance in metal corrosion due to their barrier properties and poor conductivity. In this work, first-principle calculations were performed to assess the potential ability of a series of 2D sheets for the corrosion protection of nuclear material ThO2. The strong binding interaction is found for two MXenes (Mo2C and Ti3C2 sheets) with ThO2 (111) surface revealed by their fairly low binding energy. The high binding strength of Mo2C and Ti3C2 sheets with ThO2 (111) surface originates from the remarkable charge redistribution around the interfaces. The coatings of the semiconducting 2D sheets on the ThO2 surface weaken the interaction with H2O. The one–side passivated MXenes can be efficiently anchored on the ThO2 surface through metal side, and the passivated side shows low adsorption affinity to H2O molecule. Our current work provides the basic understanding of the interaction between 2D nanosheets and ThO2 surfaces.

Hierarchical Electrode Constructed by carbon-coated Metal-Organic Framework Derivatives Supported on two-dimensional Ti3C2 nanosheets for Hybrid Li-ion Capacitors

BackgroudMetal-organic frameworks (MOFs) (e.g., Co-MOF) had been a popular platform for synthesis electrode materials for lithium-ion capacitors (LICs) because of their high theoretical specific capacity and unique structural advantages. Recent researches have focused on the development of MOFs derivative-based composites with high specific surface area, high structural stability, and high electrical conductivity. Methods: Here a distinct Ti3C2/Co3O4@C heterostructure composite was prepared by a straightforward method via hydrogen bonding with carbon-coated Co-MOF derivative anchored on Mxene-Ti3C2 nanosheets. The carbon-coated hollow Co3O4 polyhedra could shorten Li+ diffusion paths, increase the specific surface area and mitigate structural changes during the Li+ storage process. Moreover, Ti3C2 sheets were acted as a conductive network, which could increase the Li+ transport rate and stability of the structure. SignificantServing as anode material, Ti3C2/Co3O4@C electrode showed a specific capacity of 1341 mAh/g at current density of 0.1 A/g, with 93% capacity maintenance at 2 A/g after 1000 cycles in the lithium-ion half cell. Furthermore, Ti3C2/Co3O4@C//AC LIC delivered a high energy of 106 Wh/kg at 7632 W/kg. The distinct heterostructure, straightforward, and excellent performance of the Ti3C2/Co3O4@C composite as anode could provide application prospects in LICs with high energy/power density.

Multifunctional 0D@2D (Mox-Mn)Sy-NPs@MXene hybrid electrode with high rate-capability and ultra-long cycling life for Li-ion battery and all Molybdenum-MXene-based 1.9 (V) asymmetric supercapacitor

0D@2D heterostructures constituted by binary transition metal sulfides@transition metal carbides can illustrate the combined advantages of each material with their improved electrochemical performance for energy storage devices. 2D transition metal carbides (MXene ∼ Ti3C2) have presented themselves as the most appropriate candidates for the construction of lower-dimensional 0D ∼ like electroactive nanoparticles (NPs). Due to the high theoretical capacity values and versatile valence states, the molybdenum incorporated mixed metal sulfides ((Mox-Mn)Sy) nanoparticles decorated over 2D Ti3C2 sheets are reported for Li-ion battery and asymmetric supercapacitor. A uniquely designed (Mox-Mn)Sy-NPs@MXene hybrid material displays a high Li-ion storage capacity of up to 698 mA h g−1 at 50 mA g−1, and a commendable areal capacity performance (∼1.27 mA h cm−2 at 2 mA cm−2) for supercapacitor, along with outstanding capacity retention at higher current density and stable cycling performance. Furthermore, a 0D@2D (Mo-Fe7)Sx-NPs@MXene hybrid material is utilized as anode material to construct a coin cell-like (Mox-Mn)Sy-NPs@MXene//(Mo-Fe7)Sx-NPs@MXene asymmetric supercapacitor (ASC) device. A high-voltage (∼1.90 V) ASC device based on unique 0D@2D heterostructures displays an ultra-high energy density of 78.8 W h Kg−1 at a power density of 634.63 W Kg−1 along with maximum specific capacity retention and cycling stability performance. This study emphasizes the importance of 0D@2D based heterostructure materials for the development of efficient energy storage devices.

Understanding significantly reinforced polymethyl methacrylate composites induced by two‐dimensional Tin+1Cn from an atomistic perspective

AbstractMXenes, which have good reinforcing and toughening effects, can serve as excellent polymer additives. However, the mechanism whereby MXenes act has not been revealed. In this study, to understand the reinforcement effect of Tin+1Cn on polymethyl methacrylate (PMMA) from an atomistic perspective, we used molecular dynamics to conduct unidirectional tensile simulations of PMMA composites reinforced with monolayer Ti2C and Ti3C2 sheets. The results showed that Ti3C2 can more significantly improve the mechanical properties of the PMMA polymer than Ti2C, and the yield stress and Young's modulus of the Ti3C2/PMMA complexes were respectively 54.39% and 73.46% higher than the Ti2C/PMMA complexes. To further reveal the interaction mechanism between Tin+1Cn and PMMA, different separation speeds were used to simulate the pull‐out of Tin+1Cn from the PMMA matrix. The results showed that, in addition to the enhancement of interfacial strength by non‐bonding van der Waals forces, there were TiO and CTi bonds between Tin+1Cn and PMMA, which further increased the interfacial strength. Ti3C2 formed a denser interfacial region with PMMA, it could more effectively resist the formation and expansion of cracks. These findings may provide an important theoretical basis to design new type of MXene/polymer composites with excellent mechanical properties.Highlights MXene greatly improved the mechanical properties of the PMMA matrix. Formation of chemical bonds improved connection between the MXene and PMMA. The addition of MXene slows down the rate of crack propagation in PMMA.

Nickel-catalyzed synthesis of nano-diamonds during the high-temperature chlorination of the layered structured bulk of Ti3C2 under atmospheric pressure

Due to the excellent properties of nanodiamonds (NDs), the synthesis of NDs under mild conditions is very attractive but still faces great challenges. In this work, we have developed a new strategy for synthesizing NDs under atmospheric pressure, which is realized by atmospheric chlorine-etching the Ti3C2/Ni composite, where the Ni catalyst is distributed among the Ti3C2 sheets in a high-stress state. The results have shown that when the prepared Ti3C2/Ni composite is chlorine-etched under atmospheric pressure, Ni has successfully catalyzed the synthesis of NDs, where various crystalline types of NDs can be observed. The Ni-catalytic synthesis of NDs is heavily dependent upon the pressing pressure, which is used in the preparation of Ti3C2/Ni composite, and a higher pressing pressure is beneficial to the NDs formation. Furthermore, the pressing pressure has also an important effect on the crystalline type of the catalytically synthesized NDs. This discovery may provide a new strategy for tailoring the type of NDs by the pressing pressure to meet specific application requirements in the future.

The interface charge transfer induced the expanding of effective electromagnetic wave absorption band in Ti3C2/FeNi3 composites

Ti3C2/NiFe2O4 and Ti3C2/FeNi3 composites were prepared by hydrothermal and hydrazine reduction process, respectively. Effects of components and surface functionalization on dielectric/magnetic polarization of samples were studied systematically. The results indicate that the surface charge states of Ti3C2 effectively modify the dielectric performance of the corresponding samples. In Ti3C2 sheets sample, the effective absorption bandwidth (EAB) is over 2.88 GHz at thickness of 0.93 mm. In Ti3C2/NiFe2O4 composite, the EAB is about 3.92 GHz at 1.92 mm thickness. In case of Ti3C2/FeNi3 composite, its EAB exceeds 5.68 GHz at 1.59 mm thickness. Such significantly improved wave absorption performance is attributed to the additional strong interface electromagnetic loss and the optimized impedance matching. In particularly, the additional polarization induced by the charge transfer between the heterogeneous interfaces in Ti3C2/FeNi3 composite has drastic positive effects on realizing multimode synergistic attenuation of the electromagnetic energy. This work demonstrates that Ti3C2/FeNi3 composite is a novel advanced absorbent with a promising application.

Realizing Highly Efficient Sonodynamic Bactericidal Capability through the Phonon-Electron Coupling Effect Using Two-Dimensional Catalytic Planar Defects.

Conferring catalytic defects in sonosensitizers is of paramount importance in reinforcing sonodynamic therapy. However, the formation of such 0D defects is governed by the Schottky defect principle. Herein, 2D catalytic planar defects are designed within Ti3 C2 sheets to address this challenge. These specific planar slip dislocations with abundant Ti3+ species (Ti3 C2 -SD(Ti3+ )) can yield surface-bound O due to the effective activation of O2 , thus resulting in a substantial amount of 1 O2 generation and the 99.72%±0.03% bactericidal capability subject to ultrasound (US) stimulation. It is discovered that the 2D catalytic planar defects can intervene in electron transfer through the phonon drag effect-a coupling effect between surface electrons and US-triggered phonons-that simultaneously contributes to a dramatic decrease in O2 activation energy from 1.65to 0.06eV. This design has achieved a qualitative leap in which the US catalytic site has transformed from 0D to 2D. Moreover, it is revealed that the electron origin, electron transfer, and visible O2 activation pathway triggered by US can be attributed to the phonon-electron coupling effect. After coating with neutrophil membrane (NM) proteins, the NM-Ti3 C2 -SD(Ti3+ ) sheets further demonstrate a 6-log10 reduction in methicillin-resistant Staphylococcus aureus burden in the infected bony tissue.

Tissue-like Conductive Ti3C2/Sodium Alginate Hybrid Hydrogel for Electrochemical Sensing.

Endowed with a soft and conductive feature, hydrogels have been widely used as interface materials in bioelectronics to fulfill mechanical matching and bidirectional exchange between electronic platforms and living samples. Despite their ionic conductivity, the lack of electron mobility has limited their further applications in biosensing, especially in the field of electrochemical sensing. Here, we propose a Ti3C2/sodium alginate (SA) hybrid hydrogel with not only a tissue-like mechanical strength (down to 80 kPa) but also a combined exchange interface for ions and electrons, realizing both mechanical and electrical coupling toward biological tissues. Due to the shared gelation tendency with cations, the Ti3C2 sheets and SA chains can be easily in situ coassembled through a one-step electrogelation method, making the hybrid hydrogel a well-suited interface layer for device functionalization. In addition, the typical two-dimensional (2D) structure and the abundant active terminals of Ti3C2 have endowed the Ti3C2/SA with a massive loading capacity toward catalytic nanoparticles. For example, the Prussian Blue (PB)-loaded Ti3C2/SA hybrid hydrogel exhibited an excellent electrochemical performance (sensitivity: 600 nA μM-1 cm-2; LOD: 12 nM) toward hydrogen peroxide sensing in tissue fluids, illustrating a promising application potentiality of the hybrid hydrogel in biochemical detection at tissue interfaces.

Novel Electrochemical Aptasensor Based on Ordered Mesoporous Carbon/2D Ti3C2 MXene as Nanocarrier for Simultaneous Detection of Aminoglycoside Antibiotics in Milk.

Herein, a novel electrochemical aptasensor using a broad-spectrum aptamer as a biorecognition element was constructed based on a screen-printed carbon electrode (SPCE) for simultaneous detection of aminoglycoside antibiotics (AAs). The ordered mesoporous carbon (OMC) was firstly modified on 2D Ti3C2 MXene. The addition of OMC not only effectively improved the stability of the aptasensor, but also prevented the stacking of Ti3C2 sheets, which formed a good current passage for signal amplification. The prepared OMC@Ti3C2 MXene functioned as a nanocarrier to accommodate considerable aptamers. In the presence of AAs, the transport of electron charge on SPCE surface was influenced by the bio-chemical reactions of the aptamer and AAs, generating a significant decline in the differential pulse voltammetry (DPV) signals. The proposed aptasensor presented a wide linear range and the detection limit was 3.51 nM. Moreover, the aptasensor, with satisfactory stability, reproducibility and specificity, was successfully employed to detect the multi-residuals of AAs in milk. This work provided a novel strategy for monitoring AAs in milk.

Bovine serum albumin functionalized blue emitting Ti3C2 MXene quantum dots as a sensitive fluorescence probe for Fe3+ ion detection and its toxicity analysis

In the present work, an improved class of protein functionalized fluorescent 2D Ti3 C2 MXene quantum dots (MXene QDs) was prepared using a hydrothermal method. Exfoliated 2D Ti3 C2 sheets were used as the starting precursor and transport protein bovine serum albumin (BSA) was used to functionalize the MXene QDs. BSA-functionalized MXene QDs exhibited excellent photophysical property and stability at various physiological parameters. High-resolution transmission electron microscopy analysis showed that the BSA@MXene QDs were quasispherical in shape with a size of ~2 nm. The fluorescence intensity of BSA@MXene QDs was selectively quenched in the presence of Fe3+ ions. The mechanism of fluorescence quenching was further substantiated using time-resolved fluorescence and Stern-Volmer analysis. The sensing assay showed a linear response within the concentration range 0-150 μM of Fe3+ ions with excellent limit of detection. BSA@MXene QDs probe showed good selectivity toward ferric ions even in the presence of other potential interferences. The practical applicability of BSA@MXene QDs was further tested in real samples for Fe3+ ion quantification and the sensor had good recovery rates. The cytotoxicity studies of the BSA@MXene QDs toward the human glioblastoma cells revealed that BSA@MXene QDs are biocompatible at lower doses and showed significant cytotoxicity at higher dosages.

Highly-conductive Ti3C2 sheets in boosting sodium-ion storage performances of Sn2S3 anode

Sn2S3 is a promising anode candidate for sodium ion batteries (SIBs). Nevertheless, it is very hard for the Sn2S3 anode to reach its theoretical capacity even discharged at low current density. Besides, suffering from large volume expansion/shrinkage during discharge/charge processes, the utilization rate of Sn2S3 is very low and the capacity drop ratio is rather high. Enhancing the electronic conductivity and compounding with rigid second-phase material is an effective way to boost the reversible capacity and prolong the cycle life. In this contribution, super conductive and rigid Ti3C2 sheets was used to anchor the Sn2S3/Carbon (Sn2S3/C) particles. Theoretical calculation demonstrated that the negatively charged Ti3C2 sheets can efficiently boost Na + diffusion rate. Upon served the Sn2S3/C/Ti3C2 as anode of SIBs, the reversibility, rate capacity and cycle-life were all improved overwhelmingly compared to recent-reported Sn2S3-based anode. The electrochemical tests showed that Na + diffuse kinetics was enhanced by incorporating Ti3C2 sheets, which was also predicted by theoretical calculations. As expected, Sn2S3/C/Ti3C2 delivered about 920, 725, 560, 440, 330, 205 mA h g−1 at 0.1, 0.2, 0.5, 1, 2, 4 A g−1, respectively, and the utilization ratio of Sn2S3 at 0.1 A g−1 and 60th cycle surprisingly reached ∼90%. Considering the ease of operating strategy proposed in this work, it may trigger new enthusiasm for designing high-performance SIBs anode materials.

Rational fabrication of flower-like VS2-decorated Ti3C2 MXene heterojunction nanocomposites for supercapacitance performances

In this work, Ti3C2, was obtained by selective etching of Al in Ti3AlC2 by hydrofluoric and VS2 was modified on two-dimensional Ti3C2 by solvothermal process to prepare VS2/Ti3C2 composites. In the three-electrode system, the prepared VS2/Ti3C2 composites were compared with VS2 and Ti3C2, respectively, and it was found that the electrochemical properties of VS2/Ti3C2 composites were better. The intercalated VS2 nanosheets expanded the distance between Ti3C2 sheets, leading to a wide ion-accessible surface region and fast ionic/electric transport, resulting in the improved the electrochemical performance of the Ti3C2/VS2 composites. Density functional theory (DFT) analysis shows that the prepared VS2/Ti3C2 composite material has high electrical conductivity. Under the current density of 1 A∙g−1, the specific capacity of VS2/Ti3C2 composite is 191.3mAh∙g−1, which is much higher than that of VS2 and Ti3C2. The asymmetric supercapacitors were assembled with VS2/Ti3C2 composites as positive electrodes, and the electrochemical performance was tested when the power density was 1288 W·kg−1 and the energy density was 24 Wh·kg−1. The initial capacity retention is 82.2% after 5000 cycles of constant current charge and discharge at the current density of 2 A·g−1. In short, VS2/Ti3C2 composites show excellent supercapacitor performance in terms of capacity, stability, energy density and power density. It shows that VS2/Ti3C2 is a promising electrode material for supercapacitors.

The structural, magnetic, Raman and electrical transport properties of Mn intercalated Ti3C2 T X

The electronic and magnetic properties of the two-dimensional Ti3C2 MXenes have attracted a lot of interests due to its potential applications. In this paper, Ti3C2 T x MXenes and Mn-doped Ti3C2 T x MXenes are synthesized and investigated. The experimental data shows that Mn2+ ions are homogeneously and randomly intercalated between Ti3C2 sheets as function terminals, which increase the interlayer distance between Ti3C2 sheets and offer a mass of uncoupled magnetic moment. The temperature dependence of the electric resistivity of both samples show similar complex behavior although the resistivity increases dramatically as Mn doping. The inter-flake variable range hopping (VRH) dominates the low temperature electric transport behavior, while the inter-flake thermally activated hopping as well as the metallic intra-flake transport competing with the inter-flake VRH play important roles at high temperature. The increasing resistivity of the Mn-doped sample could be attributed to the increase of the interlayer distance and the enhancement of the localization of the transport electrons after Mn2+ ions intercalation.

Well-designed 2D/2D Ti3C2TA/R MXene coupled g-C3N4 heterojunction with in-situ growth of anatase/rutile TiO2 nucleates to boost photocatalytic dry-reforming of methane (DRM) for syngas production under visible light

Well-designed fabrication of 2D/2D g-C3N4/Ti3C2TA/R (CN/TCT) MXene heterojunction with in-situ growth of TiO2-nucleates for boosting photocatalytic dry reforming of methane (DRM) has been investigated. Samples were synthesized through controlled chemical etching process to construct a TiO2 (anatase/rutile) embedded Ti3C2 (TCT) with layer by layer construction of g-C3N4, resulting in higher visible light absorption and proficient charges separation. Etching Ti3AlC2 with HF (49 vol. %) produces more TiO2 compared with HF (39 vol. %), whereas, amount of TiO2 produced was dependent on reaction time. The CN/TCT composite exhibited H2 and CO rate of 51.24 and 73.31 μmole g-1 h-1, much higher than using CN and TCT. This reveals layered Ti3C2 sheets embedded anatase/rutile TiO2, enabling proficient charge carrier separation with light absorption. The effect of feed ratio (CO2/CH4) further confirmed efficient sorption process with good recyclability and would be beneficial to promote the conversion of CO2 and CH4 to syngas under visible light.

Cobalt phosphide nanoparticles grown on Ti3C2 nanosheet for enhanced lithium ions storage performances

MXene is widely used as electrode materials in lithium-ion batteries due to its unique morphology, which realizes rapid ion diffusion and provides more ion insertion channels, whereas transition metal phosphides show a promising lithium storage performance in the field of energy storage due to their high theoretical capacity. In the present paper, cobalt phosphide nanoparticles (NPs) were self-grown on Ti3C2 sheets via a low-temperature phosphating method, which showed good cycle stability as the anode in lithium-ion batteries (LIBs). After 1000 cycles, the specific capacity was maintained at 650 mAh g−1 with a high coulombic efficiency (98.8%) at 700 mA g−1, which was approximately 4 and 6 times higher than that of pristine CoP–Co2P and pure Ti3C2, respectively. The enhanced electrochemical performance was attributed to the large specific surface (61.2 m2 g−1), which offered sufficient active sites for the electrochemical reaction. Also, the outstanding redox reaction activity of cobalt phosphide effectively improved the electrochemical reaction efficiency during the charge-discharge process. The strategy proposed in this study could be extended to other two dimensional (2D) materials to achieve their full potential.

Macroscopic MXene ribbon with oriented sheet stacking for high‐performance flexible supercapacitors

AbstractFlexible and wearable fiber electrodes with high conductivity and acceptable electrochemical behavior are crucial for extending the application of next‐generation portable electronics, the development of which, however, is very challenging. Two‐dimensional sheets are known to be excellent units for assembling fiber entities, particularly when sheets are oriented in a stacking manner, which helps integrate their intrinsic in‐plane advantages, especially those related with mechanical and electronic performances. In this study, we developed a flexible macroscopic and continuous fiber in an unusual ribbon shape composed solely of Ti3C2 sheets, a typical member of the MXene family. The ribbon morphology was realized through highly ordered stacking of Ti3C2, which imparts fibers with favorable mechanical characteristics. Based on the intrinsic metallic conductivity of Ti3C2 sheets and the oriented stacking structure, the developed macroscopic ribbon exhibited excellent conductivity for both electrons (up to 2458 S/cm) and ions. A fiber‐shaped asymmetric supercapacitor using the developed macroscopic ribbon as a cathode coupled with reduced graphene oxide fibers as an anode delivered a competitive maximum volumetric energy density of 58.4 mWh/cm3 (20.0 Wh/kg) while maintaining a power level of 1679.0 mW/cm3 (581.0 W/kg) and excellent cycling stability (92.4% retention after 10 000 cycles at 10 A/g). This study highlights the excellent potential of MXene as a platform for macroscopic assembly and definitely broadens the applications of MXene materials in wearable electronics.

A strategy for effective electrochemical detection of hydroquinone and catechol: Decoration of alkalization-intercalated Ti3C2 with MOF-derived N-doped porous carbon

The functional groups on the surface of Ti3C2 can be tailored by alkalization treatment to design novel electrode materials. However, the restacking of Ti3C2 greatly hinders its practical application. To address this limitation, a facile self-assembling method was developed to engineer a novel type of heterostructure (Ti3C2/MOF). The structure alk-Ti3C2/N-PC was prepared by combining MOF-5-NH2-derived nitrogen-doped porous carbon (N-PC) with alk-Ti3C2 prepared by the acid etching and alkaline intercalation treatment of Ti3C2. This strategy could effectively prevent Ti3C2 sheets from restacking and enable the sensing of benzenediol through hydrogen-bond interaction, brought about by the abundant OH functional groups on the alk-Ti3C2 and numerous CN bonds on NPC. Because of the advantages of the excellent electrical conductivity of alk-Ti3C2 and the large surface area of NPC, hydroquinone (HQ) and catechol (CT) could be detected on the basis of their benzenediol/benzoquinone redox reactions. Under optimized conditions, a wide linear range of 0.5―150 μM with low detection limits of 4.8 nM (S/N = 3) and 3.1 nM (S/N = 3) for HQ and CT, respectively, were obtained. The alk-Ti3C2/NPC electrochemical sensor was applied to detect HQ and CT in industrial wastewater, and acceptable recoveries were achieved. Hence, the decoration of alk-Ti3C2 with NPC is an innovative method to engineer various alk-Ti3C2-based composites for the detection of phenolic isomers and environmental analyses.

Self-assembly of secondary-formed multilayer La/e-Ti3C2 as high performance supercapacitive material with excellent cycle stability and high rate capability

MXenes are a new class of two-dimensional (2D) materials and have been considered as promising energy storage materials due to their high conductivity and unique layered structure. To improve the charge storage performance of these materials, it is crucial to prevent self-stacking and expand the interlayer spacing of MXenes since this will increase the transfer channels and accessible active sites for electrolyte ions and improve the dynamics of charge storage. This paper presents an effective approach to preventing self-stacking and expanding the interlayer spacing of Ti3C2 using electrostatic reassembly between lanthanum ions and exfoliated Ti3C2 sheets to obtain a secondary-formed multilayer-structured Ti3C2 (La/e-Ti3C2). An increased interlayer spacing and greater specific surface area were achieved and capacitive performance was improved compared with that of pure multilayer Ti3C2. The specific capacitance of La/e-Ti3C2 was found to be 233.3 F g−1 at a current density of 0.5 A g−1 and the capacitance retention under 2 A g−1 was as high as 94.3% after 10,000 cycles. An interesting result is presented, namely that a large interlayer spacing is beneficial for improving the rate capability of Ti3C2 at different current densities. The study paves the way for controllable tuning of the interlayer spacing, specific surface area, and pseudocapacitive performance of two-dimensional materials.

Sonochemical self-growth of functionalized titanium carbide nanorods on Ti3C2 nanosheets for high capacity anode for lithium-ion batteries

Two-dimensional (2D) transition metal carbides (MXenes) have been considered a promising electrode material in energy storage devices due to their outstanding electrical conductivity, excellent electrochemical performance and unique surface terminations. Herein, with inspiration from the interesting functional structure of layered MXene, we report an efficient and facile sonochemical method to synthesize an anode material; functionally activated titanium carbide nanorods grown on Ti3C2 MXene nanosheets (FTCN-MXene) in deionized water and dimethylformamide mixture. In a striking contrast to pristine Ti3C2Tx MXene, FTCN-MXene exhibits outstanding specific anode capacity of 1,034 mAh/g, high coulombic efficiency (98.78%) after 250 cycles, and excellent reversible cyclic stability (retention of 96.05%). Functionalized nanorods grown on metallic conducting Ti3C2 sheets create more active sites and surface area, improving Li ion insertion/extraction capability. This study opens new avenues for developing functionalized MXene-based electrode materials with enhanced performance for electrochemical energy storage devices and systems.