Search Results (65)

The preparation of stable dispersions of MoS₂ by ultrasonic aqueous and/or organic media containing amphiphilic molecules is an attractive and widely applicable method to form MoS₂ fine particles while suppressing its aggregation. In this study, we developed a series of polymers with pendant sulfide moieties as a new dispersant, under the hypothesis that it would interact with sulfur atoms on MoS₂ surfaces. First, we designed a sulfide group-substituted methacrylate derivative (ESMA) with the hypothesis that it would interact with the MoS₂ surface through sulfur-sulfur interactions. Then, we synthesized well-defined polymers with pendant sulfide groups by living radical polymerization (ATRP). Next, 0.5 wt% MoS₂ was added to a DMSO solution containing 1 wt% of the obtained polymer (polyESMA), and the mixture was treated with a bath-type ultrasonicator for 3 h to obtain a MoS₂ dispersion. We found that stable dispersions of MoS₂ in a fine particle state, although not in the form of single-layer or few-layer nanosheets, could be readily formed in DMSO using polyESMA as a polymeric dispersant. Furthermore, we synthesized polymeric dispersants with different molecular weights and investigated the relationship between the structure of the dispersant and the dispersion stability. Full article

Two-dimensional transition metal dichalcogenides have attracted considerable attention in electrocatalytic hydrogen evolution due to their unique layered structures and tunable electronic properties. However, prior research has predominantly focused on the intrinsic catalytic activity of planar few-layer structures, which offer limited exposure of edge-active sites due to their restricted two-dimensional geometry. Moreover, van der Waals interactions between layers impose substantial barriers to electron transport, significantly hindering charge transfer efficiency. To overcome these limitations, this study presents the innovative synthesis of high-quality single-screw WS₂ with a 5° dislocation angle via physical vapor deposition. Second harmonic generation measurements revealed a pronounced asymmetric polarization response, while the selected area electron diffractionand atomic force microscopy elucidated the material’s distinctive screwed dislocation configuration. In contrast to planar monolayer WS₂, the conical/screw-structured WS₂—formed through screw-dislocation-mediated growth—exhibits a higher density of exposed edge-active catalytic sites and enhanced electron transport capabilities. Electrochemical performance tests revealed that in an alkaline medium, the screwed WS₂ nanosheets exhibited an overpotential of 310 mV at a current density of −10 mA/cm², with a Tafel slope of 204 mV/dec. Additionally, under a current density of 18 mA/cm², the screwed WS₂ can sustain this current density for at least 30 h. These findings offer valuable insights into the design of low-cost, high-efficiency, non-precious metal catalysts for hydrogen evolution reactions. Full article

A supercapacitor’s energy storage capability is greatly dependent on electrode materials. Layered double hydroxides (LDHs) were extensively studied as battery-type electrodes because of their 2D structure and quick intercalation/deintercalation of electrolyte ions. However, the energy storage capability for pristine LDHs is limited by their large aggregation tendency and poor electrical conductivity. Herein, a novel NiCoMn-LDH/SWCNTs (single-walled carbon nanotubes) composite electrode material, with ultrathin NiCoMn-LDH nanosheets dispersedly grown among the highly conductive networks of SWCNTs, was prepared via a facile zeolitic imidazolate framework-67 (ZIF-67)-derived in situ etching and deposition procedure. The NiCoMn-LDH/SWCNTs electrode demonstrates a specific capacitance as large as 1704.3 F g⁻¹ at 1 A g⁻¹, which is ascribed to its exposure of more active sites than NiCoMn-LDH. Moreover, the assembled NiCoMn-LDH/SWCNTs//BGA (boron-doped graphene aerogel) hybrid supercapacitor exhibits a superior capacitance of 167.9 F g⁻¹ at 1.0 A g⁻¹, an excellent energy density of 45.7 Wh kg⁻¹ with a power density of 700 W kg⁻¹, and an outstanding cyclic stability with 82.3% incipient capacitance maintained when subjected to 5000 charge and discharge cycles at the current density of 10 A g⁻¹, suggesting the significant potential of NiCoMn-LDH/SWCNTs as the electrode material applicable in supercapacitors. Full article

Until now, no slow-release urea (SRU) fertilizer has been made using the screw press method and the powder of plant residues rich in polyphenols, which are considered eco-friendly materials due to some health benefits for agricultural soil. Therefore, the goal of this experiment was to synthesize a novel SRU fertilizer using “eco-friendly materials” and the “screw press method”. In order to achieve this goal, urea (U) was innovatively and highly intercalated between interlayers of impure montmorillonite (Mt) (bentonite) with the help of polyphenol-rich pomegranate peel powder (PPP) by a single-screw oil press machine. The experiment had five treatments, including a fixed ratio of U/Mt (4:1) with variable ratios of U/Mt/PPP (w/w), including 4:1:0 (F₁), 4:1:1 (F₂), 4:1:1.5 (F₃), and 4:1:2 (F₄). Control (U) and F₅ treatments (U/PPP at ratio of 4:1) were also included. These composites were fabricated using a single-screw oil press machine. The produced composites were characterized using FTIR, SEM, XRD, and TG analyses. The release pattern was studied using the White method. The XRD (low-angle) results revealed that the interlayer space of Mt increased from 12.3 Å in bentonite to 19.4 Å, 27.3 Å, 25.7 Å, and 0 Å in the F₁, F₂, F₃, and F₄ composites, respectively, which is an indicator of the high intercalation of U between the interlayers of Mt, especially in the F₂ treatment. The XRD (low- and normal-angle) analyses indicated that the two main reasons for the high intercalation in the F₂ treatment were, first, the complete conversion of urea from a crystalline to an amorphous state by PPP and, second, the increase in the interlayer space of Mt nano-sheets by PPP. It seems that PPP at a low concentration (F₂) can have a positive effect on the placement of U in the interlayer space, but at high concentrations (F₄), due to intensive pectin gelation, the space between the Mt layers grows until complete exfoliation. FTIR spectra and TG analysis also confirmed this hypothesis. SEM images revealed the formation of an intensive crosslink between U, Mt, and PPP. A release test in water revealed that only 10% of U in the F₂ treatment was released after 10 h, and 87% after 120 h, which indicates the satisfactory slow-release pattern of this composite. By comparing the results of the present study with the other SRUs reported in the literature, it can be concluded that the composite F₂, in addition to offering valuable polyphenol-rich plant materials, had an acceptable performance in the aspect of the U release pattern. Full article

Molybdenum disulfide (MoS₂) with single- and odd-numbered layers is a novel piezocatalyst, and its piezocatalytic molecular oxygen activation is considered a promising and low-cost strategy for environmental remediation. In this study, the odd-numbered layers of Co-doped MoS₂ ultrathin nanosheets were successfully fabricated, which decomposed tetracycline by 99.8% in 15 min through shaking vibration. Moreover, to verify the enhanced piezoelectric catalytic activity of MoS₂ via the doping effect, molecular oxygen activation properties were predicted through DFT calculation and monitored by generated reactive oxygen species (ROS) evolution. In addition, the primary reactive species responsible for the degradation of tetracycline pollutants were also investigated in detail. Full article

Potent synthetic drugs, as well as biomolecules extracted from plants, have been investigated for their selectivity toward cancer cells. The main limitation in cancer treatment is the ability to bring such molecules within each single cancer cell, which requires accumulation in the peritumoral region followed by homogeneous spreading within the entire tissue. In the last decades, nanotechnology has emerged as a powerful tool due to its ability to protect the drug during blood circulation and allow enhanced accumulation around the leaky regions of the tumor vasculature. However, the ideal size for accumulation of around 100 nm is too large for effective penetration into the dense collagen matrix. Therefore, we propose a multistage system based on graphene oxide nanosheet-based quantum dots (GOQDs) with dimensions that are 12 nm, functionalized with hyaluronic acid (GOQDs-HA), and deposited using the layer-by-layer technique onto an oil-in-water nanoemulsion (O/W NE) template that is around 100 nm in size, previously stabilized by a biodegradable polymer, chitosan. The choice of a biodegradable core for the nanocarrier is to degrade once inside the tumor, thus promoting the release of smaller compounds, GOQDs-HA, carrying the adsorbed anticancer compound, which in this work is represented by curcumin as a model bioactive anticancer molecule. Additionally, modification with HA aims to promote active targeting of stromal and cancer cells. Cell uptake experiments and preliminary penetration experiments in three-dimensional microtissues were performed to assess the proposed multistage nanocarrier. Full article

Recently, a smart strategy for two-dimensional (2D) materials synthesis has emerged, namely space-confined chemical vapor deposition (CVD). Its extreme case is the microreactor method, in which the growth substrate is face-to-face stacked on the source substrate. In order to grow 2D transition metal dichalcogenides by this method, transition metal oxides, dispersed in very small amounts on the source substrate, are used as source materials in most of the published reports. In this paper, a colloidal dispersion of MoS₂ in saline solution is used and MoS₂ nanosheets with various shapes, sizes (between 5 and 60 μm) and thicknesses (2–4 layers) have been synthesized. Small MoS₂ flakes (regular or defective) are present on the surface of the nanosheets. Catalytic sites, undercoordinated atoms located at the edges of MoS₂ flakes and nanosheets, are produced in a high number by a layer-plus-island (Stranski–Krastanov) growth mechanism. Several double-resonance Raman bands (at 147, 177, 187, 225, 247, 375 cm⁻¹) are assignable to single phonon processes in which the excited electron is elastically scattered on a defect. The narrow 247 cm⁻¹ peak is identified as a topological defect-activated peak. These findings highlight the potential of defect engineering in material property optimization, particularly for solar water splitting applications. Full article

In a recent breakthrough in the field of two-dimensional (2D) nanomaterials, the first synthesis of a single-atom-thick gold lattice of goldene has been reported through an innovative wet chemical removal of Ti₃C₂ from the layered Ti₃AuC₂. Inspired by this advancement, in this communication and for the first time, a comprehensive first-principles investigation using a combination of density functional theory (DFT) and machine learning interatomic potential (MLIP) calculations has been conducted to delve into the stability, electronic, mechanical and thermal properties of the single-layer and free-standing goldene. The presented results confirm thermal stability at 700 K as well as remarkable dynamical stability of the stress-free and strained goldene monolayer. At the ground state, the elastic modulus and tensile strength of the goldene monolayer are predicted to be over 226 and 12 GPa, respectively. Through validated MLIP-based molecular dynamics calculations, it is found that at room temperature, the goldene nanosheet can exhibit anisotropic tensile strength over 9 GPa and a low lattice thermal conductivity around 10 ± 2 W/(m.K), respectively. We finally show that the native metallic nature of the goldene monolayer stays intact under large tensile strains. The combined insights from DFT and MLIP-based results provide a comprehensive understanding of the stability, mechanical, thermal and electronic properties of goldene nanosheets. Full article

Developing microwave absorbers with superior low-frequency electromagnetic wave absorption properties is one of the foremost important factors driving the boom in 5G technology development. In this study, via a simple hydrothermal and pyrolysis strategy, randomly interleaved CoNiO₂ nanosheets and uniformly ultrafine CoNi nanocrystals are anchored onto both sides of a single-layered MXene. The absorption mechanism demonstrated that the hierarchical heterostructure prevents the aggregation of MXene nanoflakes and magnetic crystallites. In addition, the introduction of the double-magnetic phase of CoNiO₂/CoNi arrays can not only enhance the magnetic loss capacity but also generate larger void spaces and abundant heterogeneous interfaces, collectively promoting impedance-matching and furthering microwave attenuation capabilities at a low frequency. Hence, the reflection loss of the optimal absorber (M–MCNO) is −45.33 dB at 3.24 GHz, which corresponds to a matching thickness of 5.0 mm. Moreover, its EAB can entirely cover the S-band and C-band by tailoring the matching thickness from 2 to 7 mm. Satellite radar cross-section (RCS) simulations demonstrated that the M–MCNO can reduce the RCS value to below −10 dB m² over a multi-angle range. Thus, the proposed hybrid absorber is of great significance for the development of magnetized MXene composites with superior low-frequency microwave absorption properties. Full article

Binary transition metal oxide complexes (BTMOCs) in three-dimensional (3D) layered structures show great promise as electrodes for supercapacitors (SCs) due to their diverse oxidation states, which contribute to high specific capacitance. However, the synthesis of BTMOCs with 3D structures remains challenging yet crucial for their application. In this study, we present a novel approach utilizing a single-step hydrothermal technique to fabricate flower-shaped microspheres composed of a NiCo-based complex. Each microsphere consists of nanosheets with a mesoporous structure, enhancing the specific surface area to 23.66 m² g⁻¹ and facilitating efficient redox reactions. When employed as the working electrode for supercapacitors, the composite exhibits remarkable specific capacitance, achieving 888.8 F g⁻¹ at 1 A g⁻¹. Furthermore, it demonstrates notable electrochemical stability, retaining 52.08% capacitance after 10,000 cycles, and offers a high-power density of 225 W·kg⁻¹, along with an energy density of 25 Wh·kg⁻¹, showcasing its potential for energy storage applications. Additionally, an aqueous asymmetric supercapacitor (ASC) was assembled using NiCo microspheres-based complex and activated carbon (AC). Remarkably, the NiCo microspheres complex/AC configuration delivers a high specific capacitance of 250 F g⁻¹ at 1 A g⁻¹, with a high energy density of 88 Wh kg⁻¹, for a power density of 800 W kg⁻¹. The ASC also exhibits excellent long-term cyclability with 69% retention over 10,000 charge–discharge cycles. Furthermore, a series of two ASC devices demonstrated the capability to power commercial blue LEDs for a duration of at least 40 s. The simplicity of the synthesis process and the exceptional performance exhibited by the developed electrode materials hold considerable promise for applications in energy storage. Full article

In this work, we synthesize hierarchical In₂S₃/NiFe-layered double hydroxide (In₂S₃/NiFe-LDH) nanoarrays on an F-doped SnO₂ glass substrate via a two-step method, which the In₂S₃ electrode film was firstly prepared using chemical bath deposition on F-doped SnO₂ glass substrate, and then the layered NiFe-LDH was deposited on In₂S₃ electrode film by hydrothermal synthesis. The two-component photoanode In₂S₃/NiFe-LDH exhibits significantly enhanced photoelectrochemical properties compared with the In₂S₃ single-component; due to that, the NiFe-LDH nanosheets depositing on the surface of In₂S₃ nanocrystal can reduce the accumulation of photogenic holes, facilitate the separation of photogenerated charge carriers, and enhance the light response and absorption. After being decorated with the NiFe-LDH nanosheets, the In₂S₃/NiFe-LDH photoanode displays a lower onset potential of 0.06 V and an enhanced photocurrent density as high as 0.30 mA·cm⁻² at the potential of 1.0 V (vs. RHE). Furthermore, it also displays a 90% degradation rate of xylose oxidizing into xylose acid in 3 h under UV light. This work provides a promising approach for designing new heterojunctions applied to biomass degradation. Full article

Graphene-based nanomaterials (GBNs) consist of a single or few layers of graphene sheets or modified graphene including pristine graphene, graphene nanosheets (GNS), graphene oxide (GO), reduced graphene oxide (rGO), as well as graphene modified with various functional groups or chemicals (e.g., hydroxyl, carboxyl, and polyethylene glycol), which are frequently used in industrial and biomedical applications owing to their exceptional physicochemical properties. Given the widespread production and extensive application of GBNs, they can be disseminated in a wide range of environmental mediums, such as air, water, food, and soil. GBNs can enter the human body through various routes such as inhalation, ingestion, dermal penetration, injection, and implantation in biomedical applications, and the majority of GBNs tend to accumulate in the respiratory system. GBNs inhaled and substantially deposited in the human respiratory tract may impair lung defenses and clearance, resulting in the formation of granulomas and pulmonary fibrosis. However, the specific toxicity of the respiratory system caused by different GBNs, their influencing factors, and the underlying mechanisms remain relatively scarce. This review summarizes recent advances in the exposure, metabolism, toxicity and potential mechanisms, current limitations, and future perspectives of various GBNs in the respiratory system. Full article

MOF-74 (metal–organic framework) is utilized as a filler in mixed-matrix membranes (MMMs) to improve gas selectivity due to its unique one-dimensional hexagonal channels and high-density open metal sites (OMSs), which exhibit a strong affinity for CO₂ molecules. Reducing the agglomeration of nanoparticles and improving the compatibility with the matrix can effectively avoid the existence of non-selective voids to improve the gas separation efficiency. We propose a novel, layer-by-layer modification strategy for MOF-74 with graphene oxide. Two-dimensional graphene oxide nanosheets as a supporting skeleton creatively improve the dispersion uniformity of MOFs in MMMs, enhance their interfacial compatibility, and thus optimize the selective gas permeability. Additionally, they extended the gas diffusion paths, thereby augmenting the dissolution selectivity. Compared with doping with a single component, the use of a GO skeleton to disperse MOF-74 into Pebax^®1657 (Polyether Block Amide) achieved a significant improvement in terms of the gas separation effect. The CO₂/N₂ selectivity of Pebax^®1657-MOF-74 (Ni)@GO membrane with a filler concentration of 10 wt% was 76.96, 197.2% higher than the pristine commercial membrane Pebax^®1657. Our results highlight an effective way to improve the selective gas separation performance of MMMs by functionalizing the MOF supported by layered GO. As an efficient strategy for developing porous MOF-based gas separation membranes, this method holds particular promise for manufacturing advanced carbon dioxide separation membranes and also concentrates on improving CO₂ capture with new membrane technologies, a key step in reducing greenhouse gas emissions through carbon capture and storage. Full article

In response to the trend of drug−resistant and super bacteria, the existing single antibacterial methods are not sufficient to kill bacteria, and the development of multifunctional antibacterial nanomaterials is urgent. Our study aims to construct copper−doped polydopamine−coated Ti₃C₂T_x (CuPDA@Ti₃C₂T_x) with an enhanced photothermal property and Fenton−like activity. The nanocomposite hydrogel consisting of CuPDA@Ti₃C₂T_x and alginate can improve the antioxidant activity of two−dimensional MXene nanosheets by coating them with a thin layer of PDA nanofilm. Meanwhile, Cu ions are adsorbed through the coordination of PDA−rich oxygen−containing functional groups and amino groups. Calcium ions were further used to crosslink sodium alginate to obtain antibacterial hydrogel materials with combined chemotherapy and photothermal therapy properties. The photothermal conversion efficiency of CuPDA@Ti₃C₂T_x is as high as 57.7% and the antibacterial rate of Escherichia coli reaches 96.12%. The photothermal effect leads to oxidative stress in bacteria, increases cell membrane permeability, and a high amount of ROS and copper ions enter the interior of the bacteria, causing protein denaturation and DNA damage, synergistically leading to bacterial death. Our study involves a multifunctional synergistic antibacterial nanodrug platform, which is conducive to the development of high−performance antibacterial agents and provides important research ideas for solving the problem of drug−resistant bacteria. Full article

Black phosphorus (BP), as a direct band gap semiconductor material with a two-dimensional layered structure, has a good application potential in many aspects, but the surface state of it is extremely unstable, especially that of single-layer black phosphorus. In this study, BP crystals and two-dimensional black phosphorus (2D BP) are prepared by a mechanical ball-milling–liquid-phase exfoliation method. The X-ray diffraction (XRD) spectrum and high-resolution transmission electron microscopy (HRTEM) results showed that red phosphorus (RP) successfully turned to BP by the mechanical ball-milling method. The spectrophotometric analysis has detected absorption peaks at 780 nm, 915 nm, and 1016 nm, corresponding to single, double, and three-layer BP bandgap emission. A simple solvothermal strategy is designed to synthesize in-plane BP/P-rich transition metal phosphide (TMP) heterostructures (BP/NiP₃) by defect/edge-selective growth of NiP₃ on the BP nanosheets. HRTEM analysis indicates that the metal ions are preferentially deposited on the defects of 2D BP such as edges and unsaturated sites, forming a 2D BP/NiP₃ in-plane heterojunction. Full article