Vertically aligned MoS2 nanosheets on monodisperse MXene as electrolyte-philic cathodes for zinc ion batteries with enhanced capacity.

Zinc ion batteries (ZIBs) have attracted extensive attention for their high safety and environmentally friendly nature, and considerable theoretical capacities. Due to its unique two-dimensional layered structure and high theoretical specific capacities, molybdenum disulfide (MoS2) presents as a promising cathode material for ZIBs. Nevertheless, the low electrical conductivity and poor hydrophilicity of MoS2 limits its wide application in ZIBs. In this work, MoS2/Ti3C2Tx composites are effectively constructed using a one-step hydrothermal method, where two-dimensional MoS2 nanosheets are vertically grown on monodisperse Ti3C2Tx MXene layers. Contributing to the high ionic conductivity and good hydrophilicity of Ti3C2Tx, MoS2/Ti3C2Tx composites possess improved electrolyte-philic and conductive properties, leading to a reduced volume expansion effect of MoS2 and accelerated Zn2+ reaction kinetics. As a result, MoS2/Ti3C2Tx composites exhibit high voltage (1.6 V) and excellent discharge specific capacity of 277.8 mA h g-1 at 0.1 A g-1, as well as cycle stability as cathode materials for ZIBs. This work provides an effective strategy for developing cathode materials with high specific capacity and stable structure.

Spherical Fe7S8@rGO nanoflowers as electrodes with high electrocatalytic performance in dye-sensitized solar cells.

Dye-sensitized solar cells (DSSCs) can directly convert solar energy into electricity, and have aroused great research interest from researchers. Here, the spherical Fe7S8@rGO nanocomposites were expediently fabricated by facile methods, and applied in DSSCs as counter electrodes (CEs). The morphological features show the porous structure of Fe7S8@rGO, and it is beneficial to enhance the permeability of ions. Reduced graphene oxide (rGO) has a large specific surface area and good electrical conductivity, shortening the electron transfer path. The presence of rGO promotes the catalytic reduction of I3- ions to I- ions and reduces the charge transfer resistance (Rct). The experimental findings show that the power conversion efficiency (PCE) of Fe7S8@rGO as CEs for DSSCs can reach 8.40% (20 wt% for rGO), significantly higher than Fe7S8 (7.60%) and Pt (7.69%). Therefore, Fe7S8@rGO nanocomposite is expected to be an efficient and cost-effective CE material for DSSCs.

Synthesis of Large-Area MXenes with High Yields through Power-Focused Delamination Utilizing Vortex Kinetic Energy.

Evaluating the delamination process in the synthesis of MXenes (2D transition metal carbides and nitrides) is critical for their development and applications. However, the preparation of large defect-free MXene flakes with high yields is challenging. Here, a power-focused delamination (PFD) strategy is demonstrated that can enhance both the delamination efficiency and yield of large Ti3 C2 Tx MXene nanosheets through repetitive precipitation and vortex shaking processes. Following this protocol, a colloidal concentration of 20.4 mg mL-1 of the Ti3 C2 Tx MXene can be achieved after five PFD cycles, and the yield of the basal-plane-defect-free Ti3 C2 Tx nanosheets reaches 61.2%, which is 6.4-fold higher than that obtained using the sonication-exfoliation method. Both nanometer-thin devices and self-supporting films exhibit excellent electrical conductivities (≈25 000 and 8260 S cm-1 for a 1.8 nm thick monolayer and 11 µm thick film, respectively). Hydrodynamic simulations reveal that the PFD method can efficiently concentrate the shear stress on the surface of the unexfoliated material, leading to the exfoliation of the nanosheets. The PFD-synthesized large MXene nanosheets exhibit superior electrical conductivities and electromagnetic shielding (shielding effectiveness per unit volume: 35 419 dB cm2 g-1 ). Therefore, the PFD strategy provides an efficient route for the preparation of high-performance single-layer MXene nanosheets with large areas and high yields.

Gold Catalyst Anchored to Pre-Reduced Co3O4 Nanorods for the Hydrodeoxygenation of Vanillin Using Alcohols as Hydrogen Donors.

The preparation of highly dispersed metal catalysts with strong electronic metal-support interactions (EMSIs) is of great significance. In this study, oxygen vacancies (OVs) were generated on the surfaces of Co3O4 nanorods (NRs) through NaBH4 treatment, and then the generated surface OVs were used to anchor gold clusters. The resulting catalyst was used for the hydrodeoxygenation (HDO) of vanillin based on transfer hydrogenation with alcohol donors. The conversion of vanillin and the selectivity to 2-methoxy-4-methylphenol (MMP) both reached 99% under the optimized reaction conditions, and these values were significantly higher than those obtained for the gold catalyst supported on the untreated Co3O4 NRs. The obtained results were verified by theoretical calculations and experimental data and confirmed the existence of strong EMSIs between the OV-enriched Co3O4 NRs (Co3O4 NRs-OVs) and the gold clusters, which allows electron transfer from the Co3O4 NRs to gold. Increasing the number of electrons on the gold surface can promote the catalytic hydrogen transfer of alcohol, in addition to selectively adsorbing the C═O group in vanillin to improve the selectivity toward MMP. This strategy based on the OV-anchoring of metals onto the surface of a support can be extended to other metals, thereby providing a promising method for the design of advanced and highly efficient metal catalysts.

High Concentration of Ti3C2Tx MXene in Organic Solvent.

MXenes are currently one of the most widely studied two-dimensional materials due to their properties. However, obtaining highly dispersed MXene materials in organic solvent remains a significant challenge for current research. Here, we have developed a method called the tuned microenvironment method (TMM) to prepare a highly concentrated Ti3C2Tx organic solvent dispersion by tuning the microenvironment of Ti3C2Tx. The as-proposed TMM is a simple and efficient approach, as Ti3C2Tx can be dispersed in N,N-dimethylformamide and other solvents by stirring and shaking for a short time, without the need for a sonication step. The delaminated single-layer MXene yield can reach 90% or greater, and a large-scale synthesis has also been demonstrated with TMM by delaminating 30 g of multilayer Ti3C2Tx raw powder in a one-pot synthesis. The synthesized Ti3C2Tx nanosheets dispersed in an organic solvent possess a clean surface, uniform thickness, and large size. The Ti3C2Tx dispersed in an organic solvent exhibits excellent oxidation resistance even under aerobic conditions at room temperature. Through the experimental investigation, the successful preparation of a highly concentrated Ti3C2Tx organic solvent dispersion via TMM can be attributed to the following factors: (1) the intercalation of the cation can lead to the change in the hydrophobicity and surface functionalization of the material; (2) proper solvent properties are required in order to disperse MXene nanosheets well. To demonstrate the applicability of the highly concentrated Ti3C2Tx organic solvent dispersion, a composite fiber with excellent electrical conductivity is prepared via the wet-spinning of a Ti3C2Tx (dispersed in DMF) and polyacrylonitrile mixture. Finally, various types of MXenes, such as Nb2CTx, Nb4C3Tx, and Mo2Ti2C3Tx, can also be prepared as highly concentrated MXene organic solvent dispersions via TMM, which proves the universality of this method. Thus, it is expected that this work demonstrates promising potential in the research of the MXene material family.

In Situ One-Step Synthesis of Platinum Nanoparticles Supported on Metal-Organic Frameworks as an Effective and Stable Catalyst for Selective Hydrogenation of 5-Hydroxymethylfurfural.

A facile in situ one-step route for the preparation of platinum nanoparticles supported on metal-organic frameworks (MOFs) without adding stabilizing agents was developed. The obtained 10% Pt@MOF-T3 material possessed a large surface area and high crystallinity. Meanwhile, uniform and well-dispersed platinum nanoparticles were formed inside the cavities of MOFs, which could be attributed to the efficient complexation and stabilization effect derived from the dipyridyl groups. The as-synthesized 10% Pt@MOF-T3 sample showed high activity and selectivity in the hydrogenation of 5-hydroxymethylfurfural (HMF). This excellent catalytic performance could be attributed to the synergistic effects of well-dispersed platinum nanoparticles and electron donation offered by MOFs. Meanwhile, the presence of bipyridine ligands in the MOF framework avoided the irreversible adsorption of the hydrocarbon compounds, leading to the enhanced catalytic efficiency. Besides, it was easily recycled and reused at least five times, showing good recyclability.

Ordered Mesoporous Ni-P Amorphous Alloy Nanowire Arrays: High-Efficiency Catalyst for Production of Polyol from Sugar.

Mesoporous metals have shown significant potential for use in catalysis; however, controllably synthesizing highly ordered mesoporous amorphous alloys is a serious challenge. In this paper, a synthesis strategy was developed for generating ordered amorphous alloy nanowire arrays from mesoporous Ni-P by combining mesoporous silica templating with electroless plating. Mesoporous silica is externally grafted with -CH3 and internally covered with -NH2 acting as an efficient template, ensuring the formation of Ni-P nanowires inside the pore channels and endowing the final product with an ordered mesoporous array structure. The resulting ordered mesoporous Ni-P amorphous alloy nanowire arrays were subjected to a liquid-phase sugar hydrogenation to polyols and exhibited a highly superior catalytic performance (97% glucose conversion and 94% maltose conversion) within 4 h at 4 MPa hydrogen pressure and 373 K relative to those reference catalysts, including conventionally prepared Ni-P amorphous alloy nanoparticles (87% glucose conversion and 86% maltose conversion), ordered mesoporous Ni nanowire arrays (90% glucose conversion and 87% maltose conversion), and the commercial Raney Ni catalyst (76% glucose conversion and 66% maltose conversion). According to a comparative study, the enhanced catalytic efficiencies can be ascribed to the integration of amorphous alloy properties and mesoporous material characteristics. The composition- and morphology-controllable synthesis presented here might supply a general synthetic methodology for rationally designing ordered mesoporous amorphous alloys for a broader range of applications.

An efficient defect engineering strategy to enhance catalytic performances of Co3O4 nanorods for CO oxidation.

Catalytic oxidation of CO at ambient temperature is an important reaction for many environmental applications. Here, we employed a defect engineering strategy to design an extraordinarily effective Sn-doped Co3O4 nanorods (NRs) catalyst for CO oxidation. Our combined theoretical and experimental data demonstrated that Co2+ in the lattice of Co3O4 were substituted by Sn4+. Based on a variety of characterizations and kinetic studies, this catalyst was found to combine the advantages of the nanorod-like morphology for largely exposing catalytically active Co3+ sites and the promotional effect of Sn dopant for adjusting the textural/redox properties. Additionally, the Sn-substituted Co3O4 NRs can be further activated via heat treatment to achieve low-temperature CO oxidation (T100 ∼ -100 °C) with excellent stability at ambient temperature. This study reveals the importance of Sn-substitution of inactive Co2+ in Co3O4 and provides an ultra-efficient catalyst for CO oxidation, making this robust material one of the most powerful catalysts available up to now.

Primary Amine-Functionalized Mesoporous Phenolic Resin-Supported Palladium Nanoparticles as an Effective and Stable Catalyst for Water-Medium Suzuki-Miyaura Coupling Reactions.

Metal nanoparticles have been recognized and widely explored as unique catalysts for carbon-carbon coupling reactions. However, due to their extreme tendency to agglomeration, the generation and stabilization of metal nanoparticles in a porous matrix is an important research field. Herein, novel mesoporous phenolic resin-supported palladium nanoparticles (Pd@NH2-MPRNs) were prepared via direct anionic exchange followed by gentle reduction by using primary amine-functionalized ordered mesoporous phenolic resin as the support. The obtained Pd@NH2-MPRN material still possessed large surface area and ordered two-dimensional hexagonal mesoporous structure. Meanwhile, uniform and well-dispersed palladium nanoparticles were formed in the mesoporous channels, which could be attributed to an efficient complexation and stabilization effect derived from the primary amine groups. As a result, it can promote Suzuki coupling of less activated aromatic bromides to various biaryls in water with high conversion and selectivity. This excellent performance was attributed to small particle sizes, ordered mesopores, and a hydrophobic pore surface, which resulted in the decreased diffusion limitation and the increased active site accessibility. It is noted that it is competitive with the best palladium catalysts known for water-medium Suzuki coupling reaction, and it can be reused at least seven times without significant reduction in the catalytic efficiency, showing a good recyclability. Therefore, this work provides a new potential platform for designing and fabricating robust ordered mesoporous-polymer-supported metal nanoparticles for various catalytic applications.

Synergistic Catalysis of Brønsted Acid and Lewis Acid Coexisted on Ordered Mesoporous Resin for One-Pot Conversion of Glucose to 5-Hydroxymethylfurfural.

A novel bifunctional ordered phenolic resin with Brønsted acid and Lewis acid sites (Yb(OTf)2/PhSO3H-MPR) was prepared for the first time by a two-step sulfonation and postgrafting protocol. The Brønsted acids (benzenesulfonic acids) were transformed from the phenyl groups that existed in the skeleton of ordered mesoporous phenolic resin. Meanwhile, the benzenesulfonic acids can coordinate with Yb(OTf)3 compound, resulting in the generation of Lewis acids in the pore channels of ordered phenolic resin. Yb(OTf)2/PhSO3H-MPR sample retained large specific surface and well-ordered hexagonal mesopores. As expected, it can promote one-pot cascade reaction by using glucose as the reactant to produce 5-hydroxymethylfurfural with good conversion and moderate selectivity. This synergistic catalytic performance could be attributed to its uniformly distributed Brønsted-Lewis acids. Meanwhile, the intrinsic hydrophobic pore surface can decrease the interference of water solvent, leading to enhanced catalytic efficiency. Besides, it was reused more than five times, showing good stability in water.

Delivery of Oridonin and Methotrexate via PEGylated Graphene Oxide.

Graphene oxide (GO) possessing plenty of hydroxyls and carboxyls is often used in the field of biomedicine. To improve its water solubility and biocompatibility, 6-armed poly(ethylene glycol) (PEG) was bonded on the surface of GO sheets via a facile amidation process to form the universal drug delivery platform (GO-PEG10K-6arm) with a 200 nm size in favor of the enhanced permeability and retention effect. Herein, we prepared the stable and biocompatible platform of GO-PEG10K-6arm under mild conditions and characterized the chemical structure and micromorphology via thermogravimetric analysis and atomic force microscopy. This nanosized GO-PEG10K-6arm was found to be of very low toxicity to human normal cells of 293T and tumor cells of CAL27, MG63, and HepG2. Moreover, oridonin and methotrexate (MTX), widely used hydrophobic cancer chemotherapy drugs, were compounded with GO-PEG10K-6arm via π-π stacking and hydrophobic interactions so as to afford nanocomplexes of oridonin@GO-PEG10K-6arm and MTX@GO-PEG10K-6arm, respectively. Both nanocomplexes could quickly enter into tumor cells, which was evidenced by inverted fluorescence microscopy using fluorescein isothiocyanate as a probe, and they both showed remarkably high cytotoxicity to the tumor cells of CAL27, MG63, and HepG2 within a broad range of concentration in comparison with free drugs. This kind of nanoscale drug delivery system based on GO-PEG10K-6arm may have potential applications in biomedicine, and GO-PEG10K-6arm would be a universal and available carrier for extensive hydrophobic anticarcinogens.

Production of transgenic dairy goat expressing human α-lactalbumin by somatic cell nuclear transfer.

Production of human α-lactalbumin (hα-LA) transgenic cloned dairy goats has great potential in improving the nutritional value and perhaps increasing the yield of dairy goat milk. Here, a mammary-specific expression vector 5A, harboring goat ß-lactoglobulin (ßLG) promoter, the hα-LA gene, neo(r) and EGFP dual markers, was constructed. Then, it was effectively transfected into goat mammary epithelial cells (GMECs) and the expression of hα-LA was investigated. Both the hα-LA transcript and protein were detected in the transfected GMECs after the induction of hormonal signals. In addition, the 5A vector was introduced into dairy goat fetal fibroblasts (transfection efficiency ≈60-70%) to prepare competent transgenic donor cells. A total of 121 transgenic fibroblast clones were isolated by 96-well cell culture plates and screened with nested-PCR amplification and EGFP fluorescence. After being frozen for 8 months, the transgenic cells still showed high viabilities, verifying their ability as donor cells. Dairy goat cloned embryos were produced from these hα-LA transgenic donor cells by somatic cell nuclear transfer (SCNT), and the rates of fusion, cleavage, and the development to blastocyst stages were 81.8, 84.4, and 20.0%, respectively. A total of 726 reconstructed embryos derived from the transgenic cells were transferred to 74 recipients and pregnancy was confirmed at 90 days in 12 goats. Of six female kids born, two carried hα-LA and the hα-LA protein was detected in their milk. This study provides an effective system to prepare SCNT donor cells and transgenic animals for human recombinant proteins.

[Analysis of the infection status and the drug resistance of mycoplasma and chlamydiae in genitourinary tracts of children with suspected nongonococcal urethritis].

OBJECTIVE: To investigate the infection and the drug resistance status of mycoplasma and chlamydiae in genitourinary tracts of children with suspected nongonococcal urethritis (NGU) and provide information for clinical rational administration of antimicrobial agents. METHODS: Samples of genitourinary tract secretion from 146 children who were suspected of having nongonococcal urethritis or colpitis were collected and tested for mycoplasma via culture and for chlamydia with antigen detection. Meanwhile, susceptibility test was carried out on the samples which were positive in mycoplasma cultivation. Chlamydia antigen was detected by the polymer conjugate-enhanced (PCE) indirect enzyme immunoassay (EIA) (IDEIA PCE Chlamydia; DAKO). The mycoplasma culture medium was produced by Nanjing Liming Biological Products Co,. Ltd. Antibiotics used for susceptibility test were erythromycin, roxithromycin, josamycin, leucomycin, meleumycin, rovamycin, azithromycin, clarithromycin, cycloate erythromycin, and clindamycin. RESULTS: Fifteen samples were positive for Chlamydia trachomatis (Ct) by antigen detection (10.3%), 82 samples were positive in mycoplasma cultivation (56.2%), and among the 82 samples, 58 were positive for Ureaplasma urealyticum (Uu, 39.7%), 9 were positive for Mycoplasma hominis (Mh, 6.2%), and 15 were positive for Uu and Mh (10.3%). Of all the samples, 4 were positive for both Uu and Ct (2.7%). The rates of drug resistance of the 10 commonly used antibiotics were as follows: erythromycin 32.9%, roxithromycin 41.5%, josamycin 19.5%, leucomycin 22.0%, meleumycin 28.0%, rovamycin 30.5%, azithromycin 37.8%, clarithromycin 26.8%, davercin 24.4%, and clindamycin 26.8%, respectively. The results indicated that drug resistance rates of josamycin and leucomycin were the lowest, and the rates of roxithromycin and azithromycin were the highest. CONCLUSIONS: The infection rates of mycoplasma and chlamydia in children suspected NGU were high. Mycoplasma showed drug resistance to a different degree to 10 common antibiotics. The results of chemosensitivity showed that josamycin had the highest susceptibility rate.