Nanostructured Transition Research Articles

Bandgap tuning for transition metal oxides via PEGylation

Abstract Bandgap engineering is controlled manipulation of the bandgap of materials/meta-materials to achieve desired properties. The electrical and optical properties of materials are significantly affected by bandgap tuning; therefore, bandgap engineering is a powerful technique for designing electronic and optoelectronic devices. Compositional engineering, strain engineering, and nanoscience and technology are the three major fields associated with bandgap engineering. Any unique combination of this engineering can provide novel strategies to produce novel band-structured devices. In this method article, we have demonstrated how solvation energy can alter the bandgap energy, a fact that is generally ignored due to misconceptions about quantum/size confinement. Here, we prepare nanostructured transition metal oxides (Co3O4, CuO, and ZnO) with polyethylene glycol (PEG), and the method is termed PEGylation. We investigate the influence of PEGylation on the structural, electrochemical, and electronic nature of these oxides. It is observed that the bandgap tunability (7.33%) is maximum for ZnO. Our study suggests that band alteration is significantly correlated with the change in lattice parameters; however, it is orientation dependent as the correlation coefficient reduces to 0.85 from 1 for the change in lattice parameter b along the y-axis compared to the other two lattice parameters. Similarly, band alteration is also known to have some correlation with the electrochemical potential, but is surprisingly almost independent of size confinement.

Programmable Reconfiguration of Supramolecular Bottlebrush Block Copolymers: From Solution Self-Assembly to Co-Crystallization-Assistant Self-Assembly.

Achieving structural reconfiguration of supramolecular bottlebrush block copolymers toward topological engineering is of particular interest but challenging. Here, we address the creation of supramolecular architectures to discover how assembled topology influences the structured aggregates, combining hydrogen-bonded (H-bonded) bottlebrush block copolymers and electrostatic interaction induced polymer/inorganic eutectics. We first design H-bonding linear-brush block copolymer P(NBDAP-co-NBC)-b-P(NBPEO), bearing linear block P(NBDAP-co-NBC) (poly(norbornene-terminated diaminopyridine-co-norbornene-terminated hexane)) with pendant H-bonding DAP (diaminopyridine) motifs, and PEO (poly(ethylene oxide)) densely grafted P(NBPEO) brush block. Thanks to H-bonding association between DAP and thymine (Thy), incorporation of Thy-functionalized polystyrene (Thy-PS65) enables solution self-assembly and formation of H-bonded bottlebrush block copolymers, generating augmented nanospheres with increasing Thy-PS65 amount. Noteworthy that integration of inorganic cluster silicotungstic acid (STA) to P(NBC-co-NBDAP)-b-P(NBPEO), endows the formation of PEO/STA eutectic core. Therefore, co-crystallization-assistant self-assembly at the interfaces of polymeric, inorganic and supramolecular chemistry is realized, reflecting multi-stage morphology transformation from hexagonal platelets, needle-like, curved rod-like micelles, finally to end-to-end closed rings, by gradually increasing Thy-PS65 while fixing STA content. Interestingly, such solution self-assembly to co-crystallization-assistant self-assembly strategy not only endows unique nanostructure transition, also induce in-to-out reconfiguration of PS domains. These findings clearly provide unique methodology towards programmable fabrication of geometrical objects promising in smart materials.

Self-assembly and energy storage potentials of biphasic phase change azobenzene liquid crystalline block copolymers

Flexible polymeric materials with potentials in energy storage have attracted extensive attention in today's sustainable society. Here, we reported a series of crystalline-liquid crystalline biphasic phase change block copolymers, poly(ethylene oxide)-b-poly(11-(4-(4-cyanophenylazo)phenoxy)undecane methacrylate) (PEO-b-PMAAzo), and studied the UV and Li+ ions coordination-mediated self-assembly for the potentials in phase change energy storage and solid electrolytes. The PEO-b-PMAAzo BCPs possess both the solid-liquid phase transition of PEO and the photo-chemical-thermal energy transition of PMAAzo block. Meanwhile, PEO has the capability to coordinate with the Li+ for the ionic conductivity. We explored the binary phase change behaviors and thermal energy density of the BCPs with different lithium ion concentrations before and after UV irradiation. The addition of LiTFSI salts increases the interaction parameters (χ) of the BCPs leading to phase transition of the self-assembled nanostructures. The phase diagram covering LAM, HEX, GYR, Fddd and HPL nanostructures facilitating ion transport was demonstrated. The PMAAzo block enabled the solid feature of the BCPs and ensured the high energy density and high conductivity. This work demonstrates that the combination of the functional polymers in one BCP not only provides multiple morphology tunabilities but also enables multiple functionalities from energy conversation and storage to ionic conductive electrolytes.

Robust optical picometrology through data diversity

Topologically structured light contains deeply subwavelength features, such as phase singularities, and the scattering of such light can therefore be sensitive to the geometry or movement of scattering objects at such scales. Indeed, it has been shown recently that single-shot optical measurements can yield positional precision better than 100 pm (less than one five-thousandth of the wavelength λ) via a deep-learning-enabled analysis of scattering patterns. Measurement performance, and the extent to which it can be sustained, are constrained by the quality and depth of neural network training data and the stability of the experimental apparatus. Here, we show that a neural network can be trained through exposure to an extended envelope of instrumental/ambient noise conditions to robustly quantify picometric displacements of a target against orders-of-magnitude larger background fluctuations, to maintain precision and accuracy of 100–150 pm in optical measurements (at λ = 488 nm) of nanowire positional change. This capability opens up a range of application opportunities, for example in the optical study of nanostructural dynamics, stiction, material fatigue, and phase transitions.

Programmable Reconfiguration of Supramolecular Bottlebrush Block Copolymers: From Solution Self‐Assembly to Co‐Crystallization‐Assistant Self‐Assembly

Achieving structural reconfiguration of supramolecular bottlebrush block copolymers toward topological engineering is of particular interest but challenging. Here, we address the creation of supramolecular architectures to discover how assembled topology influences the structured aggregates, combining hydrogen‐bonded (H‐bonded) bottlebrush block copolymers and electrostatic interaction induced polymer/inorganic eutectics. We first design H‐bonding linear‐brush block copolymer P(NBDAP‐co‐NBC)‐b‐P(NBPEO), bearing linear block P(NBDAP‐co‐NBC) (poly(norbornene‐terminated diaminopyridine‐co‐norbornene‐terminated hexane)) with pendant H‐bonding DAP (diaminopyridine) motifs, and PEO (poly(ethylene oxide)) densely grafted P(NBPEO) brush block. Thanks to H‐bonding association between DAP and thymine (Thy), incorporation of Thy‐functionalized polystyrene (Thy‐PS) enables solution self‐assembly and formation of H‐bonded bottlebrush block copolymers, generating augmented nanospheres with increasing Thy‐PS amount. Noteworthy that integration of inorganic cluster silicotungstic acid (STA) to P(NBC‐co‐NBDAP)‐b‐P(NBPEO), endows the formation of PEO/STA eutectic core. Therefore, co‐crystallization‐assistant self‐assembly at the interfaces of polymeric, inorganic and supramolecular chemistry is realized, reflecting multi‐stage morphology transformation from hexagonal platelets, needle‐like, curved rod‐like micelles, finally to end‐to‐end closed rings, by gradually increasing Thy‐PS while fixing STA content. Interestingly, such solution self‐assembly to co‐crystallization‐assistant self‐assembly strategy not only endows unique nanostructure transition, also induce in‐to‐out switch of PS domains. These findings clearly provide unique methodology towards programmable fabrication of geometrical objects promising in smart materials.

Quantum phase transitions in one-dimensional nanostructures: a comparison between DFT and DMRG methodologies.

In the realm of quantum chemistry, the accurate prediction of electronic structure and properties of nanostructures remains a formidable challenge. Density functional theory (DFT) and density matrix renormalization group (DMRG) have emerged as two powerful computational methods for addressing electronic correlation effects in diverse molecular systems. We compare ground-state energies ( ), density profiles ( ), and average entanglement entropies ( ) in metals, insulators and at the transition from metal to insulator, in homogeneous, superlattices, and harmonically confined chains described by the fermionic one-dimensional Hubbard model. While for the homogeneous systems, there is a clear hierarchy between the deviations, , and all the deviations decrease with the chain size; for superlattices and harmonic confinement, the relation among the deviations is less trivial and strongly dependent on the superlattice structure and the confinement strength considered. For the superlattices, in general, increasing the number of impurities in the unit cell represents lower precision in the DFT calculations. For the confined chains, DFT performs better for metallic phases, while the highest deviations appear for the Mott and band-insulator phases. This work provides a comprehensive comparative analysis of these methodologies, shedding light on their respective strengths, limitations, and applications. The DFT calculations were performed using the standard Kohn-Sham scheme within the BALDA approach. It integrated the numerical Bethe-Ansatz (BA) solution of the Hubbard model as the homogeneous density functional within a local-density approximation (LDA) for the exchange-correlation energy. The DMRG algorithms were implemented using the ITensor library, which is based on the matrix product states (MPS) ansatz. The calculations were performed until the energy reaches convergence of at least .

Nanostructured metallic enzymes mimic for electrochemical biosensing of glucose

In many domains, the creation of nonenzymatic glucose sensors with robust electrocatalytic activity and chemical stability is indispensable. However, the design of nanoarchitecture transition metals and their nanocomposites as sensing interfaces for nonenzymatic recognition groups remains a formidable challenge. This review discusses the engineered nanoarchitecture transition metals used as non-enzymatic glucose sensors, with a particular focus on their applications characterized by low cost, high sensitivity, and long-term durability. Central to our discussion is the imperative of crafting nanostructured transition materials with expansive specific surface areas and well-defined active sites to serve as electrochemical sensing platforms. Our objective is to shed light on the enhanced electrochemical behavior toward glucose without reliance on mediators or templates. Leveraging advancements in nanotechnology, this review seeks to elucidate strategies for refining conventional nanostructures to optimize enzyme-free glucose sensing applications. Additionally, we delve into the inherent challenges and potential applications of these sensors for detecting glucose and outline ways to develop better non-enzymatic electrochemical glucose sensors.

Lyotropic Liquid Crystalline Phase Nanostructure and Cholesterol Enhance Lipid Nanoparticle Mediated mRNA Transfection in Macrophages

AbstractMacrophages are unique immune cells attracting growing attention as a potential candidate for cell‐based therapy for infectious diseases and cancer. Strategies that can reprogramme or gene‐edit macrophages hold potential across a spectrum of acute and chronic conditions. Herein, lipid nanoparticles (LNPs) are developed containing the ionizable lipid SM‐102, helper lipid monoolein which is known for self‐assembly in aqueous solutions into the inverse cubic lyotropic liquid crystalline mesophase, and cholesterol as an mRNA nanocarrier. The immortalized alveolar macrophage cell line (MH‐S cells) is utilized to investigate how cholesterol concentration impacts on mRNA delivery which is further validated using primary mouse alveolar macrophages isolated from the bronchoalveolar compartment and human monocyte derived macrophages. By using high‐throughput synchrotron small angle X‐ray scattering (SAXS), an acidification‐induced non‐ordered to ordered internal nanostructure transition of the formulated LNPs is observed, following the transition sequence of inverse micellar to hexagonal to cubic mesophase in the pH range from 7 to 4. Cholesterol is identified as another crucial component for superior mRNA transfection in macrophages, contributing to nanostructure transition and protein corona variation. Successful ex vivo mRNA transfection is also achieved in primary macrophages, highlighting the prospectivity of reprogramming macrophages as a cell therapy for lung diseases.

Enhancing oxygen evolution reaction through self-reconstruction of 2D nanoarrays on nickel foam

The synthesis of nanostructured transition metal compounds with adjustable components are often challenging due to the involvement of multiple synthetic procedures or complex manipulations. In this work, a one-step self-regulating acid-etching strategy is employed for nickel iron-layered double hydroxide (NiFe LDH). A two-dimensional (2D) NiFe LDH nanosheet is speedy and efficiently formed. This as-prepared NiFe LDH exhibits electrocatalytic activity for oxygen evolution reaction (OER). This approach avoids numerous structural design challenges and provides highly active sites and a robust interface between catalyst and support. As a result, 2D NiFe LDH electrodes demonstrate highly efficient OER performance with a low overpotential of 300 mV and a Tafel slope of 70.6 mV dec−1 at a current density of 100 mA cm−2.

Compressibility Studies of Copper Selenides Obtained by Cation Exchange Reaction Revealing the New CsCl Phase.

In this study, we conducted a high-pressure investigation of Cu2-xSe nanostructures with pyramid- and plate-like morphologies, created through cation exchange from zinc-blende CdSe nanocrystals and wurtzite CdSe nanoplatelets respectively. Using a diamond anvil cell setup at the APS synchrotron, we observed the phase transitions in the Cu2-xSe nanostructures up to 40 GPa, identifying a novel CsCl-type lattice with Pm3̅m symmetry above 4 GPa. This CsCl-type structure, previously unreported in copper selenides, was partially retained after decompression. Our results indicate that the initial crystalline structure of CdSe does not affect the stability of Cu2-xSe nanostructures formed via cation exchange. Both morphologies of Cu2-xSe sintered under compression, potentially contributing to the stabilization of the high-pressure phase through interfacial defects. These findings are significant for discovering new phases with potential applications in future technologies.

Design, synthesis, and pharmacological efficacy of sonication-irradiated nanostructured transition metal (II) designed macrocyclic complexes

The synthesis of transition metal (II) complexes from aspartic acid was accomplished by using sonication irradiation in this work. Sonication irradiation is a straightforward and efficient technique for synthesis. Physiological and spectroscopic studies were carried out to investigate the process of assembling nanostructured complexes. Using the serial dilution (2-fold) and free radical scavenging (DPPH) procedures, the antioxidant and antibacterial activity were assessed, respectively. Various bacteria, including Gram-positive and Gram-negative strains and fungi, were tested to determine the antimicrobial efficacies of the macrocyclic ligand and its accompanying metal complexes. The inhibitory results on microbes showed that metal complexes had more potent antibacterial effects than their Schiff base ligands. The findings demonstrated that the biological activity had a positive impact. Sonication irradiation of some complexes increased the movement of those complexes at concentrations ranging from 3.125 to 6.250 μg/ml (MIC). The Gaussian 09 software was utilized to simulate the three-dimensional structure of the complexes, the chemical reactivity of the produced macrocyclic ligand, and the binding energy of its complexes’ EHOMO and ELUMO energies using the B3LYP Density Functional Theory (DFT) method. This method is well-suited for pharmaceutical applications in the real world since it requires little effort to set up, produces a high yield, and requires a relatively small amount of solvent.

Beyond Nanoparticle-Based Intracellular Drug Delivery: Cytosol/Organelle-Targeted Drug Release and Therapeutic Synergism.

Nanoparticle (NP)-based drug delivery systems are conceived to solve poor water-solubility and chemical/physical instability, and their purpose expanded to target specific sites for maximizing therapeutic effects and minimizing unwanted events of payloads. Targeted sites are also narrowed from organs/tissues and cells to cytosol/organelles. Beyond specific site targeting, the particular release of payloads at the target sites is growing in importance. This review overviews various issues and their general strategies during multiple steps, from the preparation of drug-loaded NPs to their drug release at the target cytosol/organelles. In particular, this review focuses on current strategies for "first" delivery and "later" release of drugs to the cytosol or organelles of interest using specific stimuli in the target sites. Recognizing or distinguishing the presence/absence of stimuli or their differences in concentration/level/activity in one place from those in another is applied to stimuli-triggered release via bond cleavage or nanostructural transition. In addition, future directions on understanding the intracellular balance of stimuli and their counter-stimuli are demonstrated to synergize the therapeutic effects of payloads released from stimuli-sensitive NPs.

Electrical and Optical Switching in Vanadium Dioxide Nanostructures Decorated with Gold Nanoparticles

The electrical parameters of the semiconductor-metal phase transition in vanadium dioxide nanostructures synthesized by chemical vapor deposition on a silicon substrate (100) and decorated with gold nanoparticles with a surface concentration from 3∙109 to 3∙1010 cm–2 are studied. X-ray phase analysis revealed that the synthesized nanostructures of vanadium dioxide contain a monoclinic M1 phase undergoing a phase transition at a temperature of about 68 °C. The morphology of the surface of vanadium dioxide nanostructures coated with gold nanoparticles was studied using a scanning electron microscope and an atomic force microscope. The characteristics of the temperature phase transition of the initial nanostructures and nanostructures decorated with gold nanoparticles are determined. The temperature dependence of the resistance near the phase transition point of the initial nanostructures showed that the resistance jump is about four orders of magnitude, which confirms their high quality. It is shown that an increase in the surface concentration of gold particles to a value of 3∙1010 cm–2 increases the conductivity of vanadium dioxide at room temperature by about two times, and shifts the phase transition temperature by 5 °C: from 68 °C to 63 °C. Optical switching in vanadium dioxide with an array of gold particles with a size of 9 nm is considered by numerical modeling methods. It is established that the response of the electromagnetic wave from the VO2 material during the phase transition is enhanced due to the excitation of localized plasmon resonance in gold nanoparticles and reaches a local maximum in the region of 600 nm. Additionally, this effect is enhanced at angles of incidence near the pseudo-Brewster angle for vanadium dioxide. The considered hybrid VO2–Au nanostructures are promising as basic nanoelements for next-generation computers, as well as for ultrafast and highly sensitive sensors.

FeNi alloys encapsulated with N-doped porous carbon nanotubes as highly efficient and durable CO2 reduction electrocatalyst

The development of highly efficient, cost-effective, and robustly stable electrocatalysts for CO2 reduction remains a significant challenge. In this study, a promising CO2 reduction electrocatalyst composed of nanostructured transition metal alloys (i.e., FeNi, FeCo, or CoNi) nanoparticles encapsulated on N-doped porous carbon material is reported. Among the different compositions, FeNi@N-CNTs-1100 exhibited the most efficient CO2ER activity and exceptional stability. It demonstrated a high CO Faradaic efficiency of over 90 % in a wide potential range (–0.47 to –0.97 V (vs. RHE)), with a CO partial current density of 20.18 mA cm−2 at –0.97 V (vs. RHE). Notably, it achieved a long-term stability of 35 h at –0.77 V (vs. RHE) in an H-cell with 0.5 M KHCO3 electrolyte. Various characterization techniques and designed experiments revealed that FeNi@N-CNTs-1100 exhibited enhanced intrinsic catalytic activity and CO selectivity due to optimized *COOH adsorption and *CO desorption compared to the other catalysts studied.

Promoting the activity of Ni3S2-x/Ni2P fuzzy-like nanorods as a bifunctional electrocatalyst for efficient overall water splitting through dealloying and active site design strategy

High-efficiency bifunctional electrocatalysts can reduce the hydrogen and oxygen evolution reaction (HER/OER) overpotential, which is of great significance for hydrogen production by water splitting. However, issues remain with large-scale preparation and a bottleneck for design separation. In this work, we reported on a facile method using a nanostructured transition metal sulfide (TMS) Ni3S2-Vs-Ps nanorod (NSVP NR) bifunctional catalyst material, which was prepared by dealloying and doping to obtain novel fuzzy-like NRs with heterostructures in triphasic points. The experimental results and first-principles calculations both revealed that the P-dopants changed the coordination environment between the inner S-vacancy Ni3S2-x NRs and outer Ni2P nanoparticles in the heterojunctions of the triphasic points, which as active sites could accelerate the movement of electron charges in the metal catalyst. The NVSP NRs showed excellent adsorption energy results, which on the Ni site were ΔGH* at 0.12 eV for HER and ΔGmax at 0.48 eV for OER. The optimized NSVP NRs demonstrated a current density of 100 mA/cm2 at the lowest overpotential of only 148 mV for HER and 311 mV for OER. Moreover, a cell voltage of 1.565 V could achieve 10 mA/cm2 when assembled in 1 M KOH solution for overall water splitting (OWS). Therefore, these findings provide a novel route from traditional dealloying corrosion for creating nanostructures and for producing new energy, offering insight into bifunctional catalyst design and application.

Transition Metal Catalysts for Atmospheric Heavy Metal Removal: A Review of Current Innovations and Advances.

Atmospheric heavy metal pollution presents a severe threat to public health and environmental stability. Transition metal catalysts have emerged as a potent solution for the selective capture and removal of these pollutants. This review provides a comprehensive summary of current advancements in the field, emphasizing the efficiency and specificity of nanostructured transition metals, including manganese, iron, cobalt, nickel, copper, and zinc. Looking forward, we delve into the prospective trajectory of catalyst development, underscoring the need for materials with enhanced stability, regenerability, and environmental compatibility. We project that advancements in computational materials science, nanotechnology, and green chemistry will be pivotal in discovering innovative catalysts that are economically and environmentally sustainable. The integration of smart technologies for real-time monitoring and adaptive control is anticipated to revolutionize heavy metal remediation, ensuring efficient and responsive pollution abatement strategies in the face of evolving industrial scenarios and regulatory landscapes.

ТЕРМОДИНАМИЧЕСКИЙ АНАЛИЗ ПРОЦЕССА ФОРМИРОВАНИЯ НАНОСТРУКТУРНОГО ПОЛИКРИСТАЛЛИЧЕСКОГО МАТЕРИАЛА НА ОСНОВЕ НАНОАЛМАЗОВ, МОДИФИЦИРОВАННЫХ НЕАЛМАЗНЫМ УГЛЕРОДОМ (ЧАСТЬ 1)

The influence of the size of carbon particles on the parameters of the graphite–diamond phase transformation is considered. It is shown that the surface energy of carbon nanoparticles of various shapes (spherical, columnar) makes a significant contribution to their total thermodynamic potential, which leads to a shift in the diamond–graphite equilibrium curve to the low pressure region and an expansion of the diamond phase stability region. At the same time, the change in the chemical potential (Gibbs free energy) during the direct (not catalytic) transition of thin-film graphite-like nanostructures into diamond will be higher than for “massive” graphite, which leads to an increase in the pressure of phase transformation into diamond. To reduce the parameters of diamond formation and obtain nanostructured diamond polycrystals, it is proposed to use nanodiamond particles with a nanometer surface layer of non-diamond (graphitelike) carbon as the starting material. In this case, the nanodiamond surface will influence the transition of a nanometer layer of graphite (graphite-like carbon) into diamond under more favorable thermodynamic parameters.

Pd-doped flower like magnetic MnFe2O4 spinel ferrit nanoparticles: Synthesis, structural characterization and catalytic performance in the hydrazine-borane methanolysis

MnFe2O4 nanoparticles, an important member of nanostructured transition metal oxides, also known as spinel ferrites, find wide use in many applications, especially medicine and catalysis, due to their fascinating properties. In this research article, MnFe2O4 and MnFe2O4 supported Pd0 nanoparticles were primarily prepared by solvothermal and impregnation/reduction methods, respectively. After the structural and morphological examination of the MnFe2O4 decorated Pd0 nanoparticles (Pd@MnFe2O4), their catalytic activity was tested in the release of hydrogen from the methanolysis of hydrazine-borane. The morphological characterizations of Pd@MnFe2O4 catalyst show that Pd0 nanoparticles were successfully decorated (average particle size ∼2.83 nm) on the flower-like MnFe2O4 spinel ferrite nanoparticles. The Pd@MnFe2O4 catalyst presented high catalytic performance in the H2 production via the methanolysis of hydrazine-borane, and the turn-over frequency value at 298 K was 47.2 min−1, which is the highest catalytic systems in the literature for this purpose. The Pd@MnFe2O4 catalyst displaying good activity in ten consecutive catalytic runs can be considered a good heterogeneous catalyst for the hydrogen production from the methanolysis of hydrazine-borane.

Temperature-Induced Nanostructure Transition for Supramolecular Gelation in Water.

Thermogel is an injectable biomaterial that functions at body temperatures due to the ease of the sol-to-gel transition. However, most conventional physically cross-linked thermogels generally have relatively low stiffness, which limits various biomedical applications, particularly for stem-cell-based studies. While chemical cross-linking through double-network (DN) structures can increase the stiffness of the hydrogel, they generally lack injectable and thermoresponsive properties due to strong covalent bonds between molecules. To address this challenge, we have developed a temperature-induced nanostructure transition (TINT) system for preparing physical DN supramolecular hydrogels. These hydrogels possess injectable, thermoreversible characteristics and relatively high storage modulus (G'), which increases ∼14-fold from 20 to 37 °C (body temperature). Our bottom-up strategy is based on the co-assembly of aromatic peptide (Ben-FF) and poly(ethylene glycol) (PEG) to form a thermogel at 37 °C through a nanofiber dissociation pathway that differs from the well-known micelle aggregation or polymer shrinkage mechanisms. Peptide molecules form helical packing and weak, noncovalent interactions with PEG, resulting in co-assembled metastable nanofibers. Thermal perturbation initiates lateral dissociation of nanofibers into extensively cross-linked DN nanostructures and subsequent hydrogelation (ΔG = -13.32 kJ/mol). The TINT hydrogel is nontoxic to human mesenchymal stem cells and supports enhanced cell adhesion, suggesting the potential of this strategy in the applications of tissue engineering and regenerative medicine.

A Highly Conductive and Supercapacitive MXene/N-CNT Electrode Material Derived from a MXene-Co-Melamine Precursor

MXene is a two-dimensional nanostructured transition metal carbon/nitride and carbon nanotubes (CNTs) are a one-dimensional graphitized carbon material, which are widely exploited for their large specific surface and excellent electrical conductivity, but the easy aggregation limits their performance. In this work, a MXene-Co-melamine precursor is elaborately assembled by coordination bonds and a highly dispersed MXene/N-CNT composite material is ultimately constructed via a segmental pyrolysis of the MXene-Co-melamine precursor. This strategy synchronously relieves the self-restacking problem of MXene and N-CNTs. The optimal 0.60-MXene/N-CNT is composed of abundant and homogeneous CNTs with a high nitrogen dosage of 5.879 wt %. And it has a large BJH adsorption average pore size of 11.5 nm, a high microporous–mesoporous distribution of 1.94% micropores and 61.67% mesopores, and a well-matched hierarchical pore structure. Due to the orderly assembled porous structure of MXene and N-CNTs, the 0.60-MXene/N-CNT exhibits a high specific capacitance of 167.2 F g–1 at 0.5 A g–1. The assembled 0.60-MXene/N-CNT//AC asymmetric supercapacitor maintains a high capacitance retention of 73.2% after 10,000 cycles at 5 A g–1 current density and a high Coulomb efficiency of 97.5%. Its energy density also can reach 12.1 Wh kg–1 at a power density of 195.4 W kg–1.