Stable and Active Au Catalyst Supported on CeMnO3 Perovskite for Selective Oxidation of Glycerol.

The selective oxidation of glycerol holds promise to transform glycerol into value-added chemicals. However, it remains a big challenge to achieve satisfactory selectivity toward the specific product at high conversion due to the multiple reaction pathways. Here, we prepare a hybrid catalyst via supporting Au nanoparticles on CeMnO3 perovskite with a modest surface area, achieving promoted conversion of glycerol (90.1%) and selectivity of glyceric acid (78.5%), which are much higher than those of CeMnOx solid-solution-supported Au catalysts with larger surface area and other Ce-based or Mn-based Au catalysts. The strong interaction between Au and CeMnO3 perovskite facilitates the electron transfer from the B-site metal (Mn) in the CeMnO3 perovskite to Au and stabilizes Au nanoparticles, which results in the enhanced catalytic activity and stability for glycerol oxidation. Valence band photoemission spectral analysis reveals that the uplifted d-band center of Au/CeMnO3 promotes the adsorption of the glyceraldehyde intermediate on the catalyst surface, which benefits further oxidation of glyceraldehyde into glyceric acid. The flexibility of the perovskite support provides a promising strategy for the rational design of high-performance glycerol oxidation catalysts.

Highly selective electrodeposition of sub-10 nm crystalline noble metallic nanorods inside vertically aligned multiwall carbon nanotubes.

In this paper crystalline noble metallic nanorods including Au and Ag with sub-10 nm diameter, are encapsulated within prealigned and open-ended multiwall carbon nanotubes (MWCNTs) through an electrodeposition method. As the external surface of CNTs has been insulated by the epoxy the CNT channel becomes the only path for the mass transport as well as the nanoreactor for the metal deposition. Highly crystallized Au and Ag2O nanorods parallel to the radial direction of CNTs are confirmed by high-resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and x-ray powder diffraction spectroscopy. The Ag2O nanorods are formed by air oxidation on the Ag metals and show a single crystalline structure with (111) planes. The Au nanorods exhibit a complex crystalline structure including twin-crystal and lattice dislocation with (111) and (200) planes. These crystalline noble metallic nanostructures may have important applications for nanocatalysts for fuel cells as well as nanoelectronic and nanophotonic devices. This method is deemed to benefit the precise deposition of other crystalline nanostructures inside CNTs with a small diameter.

Fluorescent studies on the interaction of DNA and ternary lanthanide complexes with cinnamic acid-phenanthroline and antibacterial activities testing.

Twelve lanthanide complexes with cinnamate (cin(-) ) and 1,10-phenanthroline (phen) were synthesized and characterized. Their compositions were assumed to be RE(cin)3 phen (RE(3+) = La(3+) , Pr(3+) , Nd(3+) , Sm(3+) , Eu(3+) , Gd(3+) , Tb(3+) , Dy(3+) , Ho(3+) , Tm(3+) , Yb(3+) , Lu(3+) ). The interaction mode between the complexes and DNA was investigated by fluorescence quenching experiment. The results indicated the complexes could bind to DNA and the main binding mode is intercalative binding. The fluorescence quenching constants of the complexes increased from La(cin)3 phen to Lu(cin)3 phen. Additionally, the antibacterial activity testing showed that the complexes exhibited excellent antibacterial ability against Escherichia coli, and the changes of antibacterial ability are in agreement with that of the fluorescence quenching constants.

Synthesis, crystal structure and fluorescence properties of terbium complexes with phenoxyacetic acid and 2,4,6-tris-(2-pyridyl)-s-triazine.

Two complexes of Tb(3+), Gd(3+) /Tb(3+) and one heteronuclear crystal Gd(3+)/Tb(3+) with phenoxyacetic acid (HPOA) and 2,4,6-tris-(2-pyridyl)-s-triazine (TPTZ) have been synthesized. Elemental analysis, rare earth coordination titration, inductively coupled plasma atomic emission spectrometry (ICP-AES) and thermogravimetric analysis-differential scanning calorimetry (TG-DSC) analysis show that the two complexes are Tb2 (POA)6 (TPTZ)2 · 6H2O and TbGd(POA)6 (TPTZ)2 · 6H2O, respectively. The crystal structure of TbGd(POA)6 (TPTZ)2 · 2CH3OH was determined using single-crystal X-ray diffraction. The monocrystal belongs to the triclinic system with the P-1 space group. In particular, each metal ion is coordinately bonded to three nitrogen atoms of one TPTZ and seven oxygen atoms of three phenoxyacetic ions. Furthermore, there exist two coordinate forms between C6H5OCH2COO(-) and the metal ions in the crystal. One is a chelating bidentate, the other is chelating and bridge coordinating. Fluorescence determination shows that the two complexes possess strong fluorescence emissions. Furthermore, the fluorescence intensity of the Gd(3+)/Tb(3+) complex is much stronger than that of the undoped complex, which may result from a decrease in the concentration quench of Tb(3+) ions, and intramolecular energy transfer from the ligands coordinated with Gd(3+) ions to Tb(3+) ions.

Synthesis, characterization and luminescent properties of europium complexes with 2,4,6-tris-(2-pyridyl)-s-triazine as highly efficient sensitizers.

Using 2,4,6-tris-(2-pyridyl)-s-triazine (TPTZ) as a neutral ligand, and p-hydroxybenzoic acid, terephthalic acid and nitrate as anion ligands, five novel europium complexes have been synthesized. These complexes were characterized using elemental analysis, rare earth coordination titrations, UV/vis absorption spectroscopy and infrared spectroscopy. Luminescence spectra, luminescence lifetime and quantum efficiency were investigated and the mechanism discussed in depth. The results show that the complexes have excellent emission intensities, long emission lifetimes and high quantum efficiencies. The superior luminescent properties of the complexes may be because the triplet energy level of the ligands matches well with the lowest excitation state energy level of Eu(3+). Moreover, changing the ratio of the ligands and metal ions leads to different luminescent properties. Among the complexes, Eu2(TPTZ)2(C8H4O4)(NO3)4(C2H5OH)·H2O shows the strongest luminescence intensity, longest emission lifetime and highest quantum efficiency.

Nickel Nanoparticles Protruding from Molybdenum Carbide Micropillars with Carbon Layer-Protected Biphasic 0D/1D Heterostructures for Efficient Water Splitting.

It remains a tremendous challenge to achieve high-efficiency bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) for hydrogen production by water splitting. Herein, a novel hybrid of 0D nickel nanoparticles dispersed on the one-dimensional (1D) molybdenum carbide micropillars embedded in the carbon layers (Ni/Mo2C@C) was successfully prepared on nickel foam by a facile pyrolysis strategy. During the synthesis process, the nickel nanoparticles and molybdenum carbide were simultaneously generated under H2 and C2H2 mixed atmospheres and conformally encapsulated in the carbon layers. Benefiting from the distinctive 0D/1D heterostructure and the synergistic effect of the biphasic Mo2C and Ni together with the protective effect of the carbon layer, the reduced activation energy barriers and fast catalytic reaction kinetics can be achieved, resulting in a small overpotential of 96 mV for the HER and 266 mV for the OER at the current density of 10 mA cm-2 together with excellent durability in 1.0 M KOH electrolyte. In addition, using the developed Ni/Mo2C@C as both the cathode and anode, the constructed electrolyzer exhibits a small voltage of 1.55 V for the overall water splitting. The novel designed Ni/Mo2C@C may give inspiration for the development of efficient bifunctional catalysts with low-cost transition metal elements for water splitting.

HBOT has a better cognitive outcome than NBH for patients with mild traumatic brain injury: A randomized controlled clinical trial.

BACKGROUND: Normobaric hyperoxia (NBH) and hyperbaric oxygen therapy (HBOT) are effective treatment plan for traumatic brain injury (TBI). The aim of this study was to compare cognitive outcome after mild TBI between NBH and HBOT so as to provide a more suitable treatment strategy for patients with mild TBI. METHODS: A prospective research was conducted between October 2017 and March 2023, enrolling patients with mild TBI (Glasgow coma scale score: 13-15 points) within 24 hours of injury in Cangzhou Central Hospital. Patients were randomized into 3 groups: group control (C), group NBH and group HBOT. The patients in HBOT group received hyperbaric oxygen therapy in high pressure oxygen chamber and patients in NBH group received hyperbaric oxygen therapy. at 0 minute before NBH or HBOT (T1), 0 minute after NBH or HBOT (T2) and 30 days after NBH or HBOT (T3), level of S100ß, NSE, GFAP, HIF-1α, and MDA were determined by ELISA. At the same time, the detection was performed for MoCA and MMSE scores, along with rSO2. RESULTS: The results showed both NBH and HBOT could improve the score of MoCA and MMSE, as well as the decrease the level of S100ß, NSE, GFAP, HIF-1α, MDA, and rSO2 compared with group C. Furthermore, the patients in group HBOT have higher score of MoCA and MMSE and lower level of S100ß, NSE, GFAP, HIF-1α, MDA, and rSO2. CONCLUSION: Both NBH and HBOT can effectively improve cognitive outcome for patients with mild TBI by improving cerebral hypoxia and alleviating brain injury, while HBOT exert better effect than NBH.

SOx-modified porous carbon as a highly active electrocatalyst for efficient H2O2 generation.

A SOx-decorated porous carbon electrocatalyst that exhibits excellent 2e- oxygen reduction reaction activity is synthesized using UV-curing technology in combination with a pyrolysis process. The H2O2 selectivity using the SOx-porous C shows 95.1% at 0.4 V and delivers a H2O2 production rate of 604.2 mmol gcat-1 h-1. Density-functional theory calculations reveal the reasons for the improvement of catalytic performance.

Cd2+ and Zn2+ Complexes with 2,4,6-Tri(2-pyridyl)-s-Triazine and Terephthalate for Rapid, High-Capacity Adsorption of Congo Red.

Three crystal complexes were designed and synthesised through the solvothermal method, with Cu2+ , Zn2+ , and Cd2+ ions as the metal centres and 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ) and terephthalate (BDC2- ) as the ligands. Their compositions were determined to be Cd(TPTZ)Cl2 (Cd-MOF), {[Zn(TPTZ)(BDC)] ⋅ 3H2 O}n (Zn-MOF), and Cu2 (PCA)2 (BDC)(H2 O)2 (Cu-MOF) (PCA- =2-pyridinium amide), respectively. Cd-MOF can adsorb 90 % of Congo red (CR) in 10 s at room temperature and atmospheric pressure, and CR removal was complete at 20 s over a wide pH range. The adsorption capacity for CR reached 1440 mg g-1 in 5 min. Selective adsorption was demonstrated in mixed dyes. The adsorption kinetic data agree well with the pseudo-second-order kinetic model. The Temkin model was successfully used to evaluate the adsorption isotherms of CR on Cd-MOF at room temperature, suggesting that adsorption occurs through a hybrid of monolayer and multilayer mechanisms.

Gold Nanoparticles on Nanosheets Derived from Layered Rare-Earth Hydroxides for Catalytic Glycerol-to-Lactic Acid Conversion.

Layered rare-earth hydroxides (LREHs), as a series of special lamellar compounds having a similar structure to layered double hydroxides (LDHs), are becoming a new type of catalyst materials. In this study, we have prepared a series of uniform LREH (RE = Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Tm) nanosheets through a reverse-microemulsion method. After deposition-precipitation of HAuCl4 and calcination, supported Au catalysts (denoted as Au/LREO) were subsequently obtained. The catalytic properties of all the derived Au/LREO catalysts were evaluated by aerobic conversion of glycerol to lactic acid under mild conditions (90 °C, 1 atm). Among these catalysts, Au/LPrO displays the best performances, including the highest glycerol conversion, lactic acid, and C3 product selectivity. Both the catalytic activities and the characterizations of the structure of Au/LREO indicate that the kind of rare-earth ions plays a key role in determining the Au particle size and its valence state and reducibility, which are the important factors correlated with the catalytic activities in glycerol conversion. In fact, the three features of gold particles, the extra-small size (∼3 nm), high content of Au0 species, and high reducibility, are the essential prerequisites for achieving the superior catalytic performance of Au/LPrO.

Construction of a molybdenum and copper co-doped nickel phosphide with lattice distortion for highly efficient electrochemical water splitting.

A self-supported dual-cation (Mo,Cu) co-doped Ni2P@ nickel foam catalyst (Mo,Cu-Ni2P@NF) has been prepared, and the co-doped samples can distort the lattice and expose a larger specific surface area, which provides more reaction locations, and exhibit an efficient water splitting performance.

Decoration of gold nanoparticles on surface-grown single-walled carbon nanotubes for detection of every nanotube by surface-enhanced Raman spectroscopy.

An electroless deposition method comprised of seed formation and subsequent seeded growth is developed for the decoration of surface-grown single-walled carbon nanotubes (SWCNTs) with gold nanoparticles of controlled size and interparticle distance. The density of the gold nanoparticles is determined by the density of seeds. Gold seeds are used for the SWCNT arrays grown on SiO(x)/Si substrates. For the dense SWCNT arrays on quartz, palladium seeds are used because it is much easier to obtain higher quantities of seeds. Attributed to both the seed formation specified on SWCNTs and the succedent efficient seeded growth process, the gold nanoparticles deposit on SWCNTs with very high selectivity. This electroless method shows no selectivity on types, defects, and conductivity of the SWCNTs, and thus ensures the uniform decoration of all SWCNTs on the wafer. Most importantly, this method provides the possibility to realize the optimal configurations of gold nanoparticles on SWCNTs for obtaining maximal surface-enhanced effects and consequently surface-enhanced Raman spectrum (SERS) of each SWCNT. Thus, both the in situ Raman detection of every SWCNT including those nonresonant with laser energy and the observation of the radial breathing modes of SWCNTs originally undetectable with resonance Raman spectroscopy are achieved. Further investigations over the effect of the laser wavelength and the interparticle distance on the SERS enhancement factors of SWCNTs prove that the coupled surface plasmon resonance absorption of the high-density gold nanoparticles decorated on SWCNTs contributes most to the strong surface enhancement.

Seed-mediated growth of ZnO nanorods on multiwalled carbon nanotubes.

The heterostructures of ZnO nanorods on multiwalled carbon nanotubes (MWNTs) were fabricated by a seed-mediated growth method. First, the surfaces of the carbon nanotubes (CNTs) were coated in situ with mono-dispersed ZnO nanocrystals of about 7 nm by the reaction of zinc acetate and sodium hydroxide. These nanocrystals were then served as the seeds for further growth of ZnO nanorods. In the second step, ZnO nanorods were grown on MWNTs coated with ZnO nanocrystals in an aqueous solution of zinc nitrate and equimolar hexamethylenetetramine at 85 degrees C. Typically, the ZnO nanorods had the length of 300-600 nm and the diameter of 40-140 nm and took a random direction on the outside walls of MWNTs. The morphology of the ZnO nanorods was dependent on pH, reactant concentration, and growing time.

Effect of the Composition of Lanthanide Complexes on Their Luminescence Enhancement by Ag@SiO2 Core-Shell Nanoparticles.

Metal-enhanced luminescence of lanthanide complexes by noble metal nanoparticles has attracted much attention because of its high efficiency in improving the luminescent properties of lanthanide ions. Herein, nine kinds of europium and terbium complexes-RE(TPTZ)(ampca)3·3H2O, RE(TPTZ)(BA)3·3H2O, RE(phen)(ampca)3·3H2O, RE(phen)(PTA)1.5·3H2O (RE = Eu, Tb) and Eu(phen)(BA)3·3H2O (TPTZ = 2,4,6-tri(2-pyridyl)-s-triazine, ampca = 3-aminopyrazine-2-carboxylic acid, BA = benzoic acid, phen = 1,10-phenanthroline, PTA = phthalic acid)-have been synthesized. Meanwhile, seven kinds of core-shell Ag@SiO2 nanoparticles of two different core sizes (80-100 nm and 40-60 nm) and varied shell thicknesses (5, 12, 20, 30 and 40 nm) have been prepared. The combination of these nine types of lanthanide complexes and seven kinds of Ag@SiO2 nanoparticles provides an opportunity for a thorough investigation of the metal-enhanced luminescence effect. Luminescence spectra analysis showed that the luminescence enhancement factor not only depends on the size of the Ag@SiO2 nanoparticles, but also strongly relates to the composition of the lanthanide complexes. Terbium complexes typically possess higher enhancement factors than their corresponding europium complexes with the same ligands, which may result from better spectral overlap between the emission bands of Tb complexes and surface plasmon resonance (SPR) absorption bands of Ag@SiO2. For the complexes with the same lanthanide ion but varied ligands, the complexes with high enhancement factors are typically those with excitation wavelengths located nearby the SPR absorption bands of Ag@SiO2 nanoparticles. These findings suggest a combinatorial chemistry strategy is necessary to obtain an optimal metal-enhanced luminescence effect for lanthanide complexes.

Direct Exfoliation of Natural SiO2-Containing Molybdenite in Isopropanol: A Cost Efficient Solution for Large-Scale Production of MoS2 Nanosheetes.

The cost-effective exfoliation of layered materials such as transition metal dichalcogenides into mono- or few- layers is of significant interest for various applications. This paper reports the preparation of few-layered MoS2 from natural SiO2-containing molybdenite by exfoliation in isopropanol (IPA) under mild ultrasonic conditions. One- to six-layer MoS2 nanosheets with dimensions in the range of 50-200 nm are obtained. By contrast, MoS2 quantum dots along with nanosheets are produced using N-methyl-pyrrolidone (NMP) and an aqueous solution of poly (ethylene glycol)-block-poly (propylene glycol)-block-poly (ethylene glycol) (P123) as exfoliation solutions. Compared with molybdenite, commercial bulk MoS2 cannot be exfoliated to nanosheets under the same experimental conditions. In the exfoliation process of the mineral, SiO2 associated in molybdenite plays the role of similar superfine ball milling, which significantly enhances the exfoliation efficiency. This work demonstrates that isopropanol can be used to exfoliate natural molybdenite under mild conditions to produce nanosheets, which facilitates the preparation of highly concentrated MoS2 dispersions or MoS2 in powder form due to the volatility of the solvent. Such exfoliated MoS2 nanosheets exhibit excellent photoconductivity under visible light. Hence, the direct mild exfoliation method of unrefined natural molybdenite provides a solution for low-cost and convenient production of few-layered MoS2 which is appealing for industrial applications.

Tuning the luminescence properties of lanthanide coordination polymers with Ag@SiO2 nanoparticles.

A series of core-shell Ag@SiO2 nanoparticles with different core diameters and shell thicknesses have been prepared by a modified-Stöber method. They provide a facile route to tune the luminescence intensities, lifetimes and quantum efficiencies of lanthanide coordination polymers in the solid powder state. The coordination polymers [Tb2(p-PTA)3(H2O)2]n, [Tb2(o-PTA)3(H2O)2]n, [Eu2(p-PTA)3(H2O)2]n and [Eu2(o-PTA)3(H2O)2]n (PTA = phthalic acid) are synthesized and subsequently bound to the surface of Ag@SiO2 nanoparticles. The luminescence intensities of the lanthanide complexes are enhanced as high as 10.8 times. The enhancement times depend on the core diameter and shell thickness of the Ag@SiO2 nanoparticles. Importantly, by simply controlling the ratios between the complexes and the nanoparticles, the luminescence intensities, lifetimes and quantum efficiencies of the lanthanide complexes can be tuned in wide ranges. Typically, the luminescence lifetime of [Eu2(p-PTA)3(H2O)2]n powder increases from 451 µs to 783 µs when 300 µL Ag@SiO2 solution is added. Meanwhile, the luminescence quantum efficiency of the complex increases from 32.1% to 40.9%. The change of the luminescence properties of the lanthanide coordination polymers can be ascribed to the surface plasmon resonance effect of the Ag@SiO2 nanoparticles as well as the decrease of the nonradiative decay rates of the complexes.

Creation of cadmium sulfide nanostructures using AFM dip-pen nanolithography.

A dip-pen nanolithography (DPN) process capable of depositing nanoscaled structures of semiconducting CdS materials was developed by careful control of the reaction speed between the precursors. The new development expanded the scope of the powerful DPN process and provided more insight in the deposition mechanism. Features ranging from several hundreds of nanometers to sub-50 nanometers were generated and characterized. The effects of the surface property of the substrate, the relative humidity, the translating rate, and the temperature were systematically investigated. X-ray photoelectron spectroscopy (XPS) was used to verify the chemical composition of the patterns. In principle, this simple and convenient method should be applicable to deposit various metal sulfides on suitable substrates.

Fluorescence enhancement of europium complexes by core-shell Ag@SiO2 nanoparticles.

Three kinds of core-shell Ag@SiO2 nanoparticles with shell thickness of around 10, 15, and 25 nm, respectively, have been prepared by modified Stöber method and used for fluorescence enhancement. Six kinds of europium complexes with halobenzoic acid have been synthesized. Elemental analysis and lanthanide coordination titration show that the complexes have the compositions of Eu(p-XBA)3·H2O and Eu(o-XBA)3·2H2O (X=F, Cl, Br). The fluorescence spectra investigation indicates that the introduction of Ag@SiO2 nanoparticles into the europium complexes' solution can significantly enhance the fluorescence intensities of the complexes. The sequence of enhancement factors for halobenzoic acid complexes with different halogen atoms is F

Crystal structure and photoluminescence of two europium compounds with phenoxyacetic acid and 2,4,6-tri(2-pyridyl)-s-triazine.

Two novel crystal compounds of Eu(3+) and Gd(3+)/Eu(3+) with phenoxyacetic acid (HPOA) and 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ) have been synthesized. The two compounds are characterized by elemental analysis, rare earth coordination titrations, molar conductivity measurements, UV-vis absorption spectroscopy and IR spectroscopy. The crystal structures of compounds 1 Eu2(TPTZ)2(POA)6·2CH3OH and 2 EuGd(TPTZ)2(POA)6·2CH3OH were determined by single-crystal X-ray diffraction. The two monocrystals belong to the triclinic system and space group P1[combining macron] with the following unit cell parameters: a = 12.2448(10), 12.2476(6) Å; b = 13.2214(11), 13.2260(7) Å; c = 13.5248(12), 13.5210(7) Å; α = 74.8544(15), 74.8810(10)°; ß = 83.0605(16), 83.0465(8)°; γ = 87.1996(14), 87.2126(8)°; V = 2097.7(7), 2098.5(19) Å(3) and Z = 1, respectively. They are both dinuclear: one is homonuclear and the other is heteronuclear. Each metal ion is coordinately bonded to three nitrogen atoms of one TPTZ and seven oxygen atoms of three phenoxyacetate ions. Furthermore, there exist two coordinate forms between C6H5OCH2COO(-) and metal ions. One is chelating bidentate and the other is chelating and bridge coordinating. The triplet energy level of phenoxyacetic acid was measured, which is approximately 22,500 cm(-1), indicating that the lowest excitation state energy level of Eu(III) and the triplet state energy level of phenoxyacetic acid match well with each other. The luminescent emission intensity of both compounds was very strong. Besides, the results indicate that the luminescent emission intensity, luminescence lifetimes and the emission quantum efficiencies of Gd(3+)/Eu(3+) compound 2 are remarkably superior to those of compound 1, respectively. This phenomenon may mainly result from the decrease of the concentration quenching effect of Eu(3+) ions, and the intramolecular energy transfer from the ligands coordinated with Gd(3+) ions to Eu(3+) ions.

Preparation and electrochemical properties of MnO2 nanosheets attached to Au nanoparticles on carbon nanotubes.

A wet chemical route for the preparation of MnO(2) nanosheet/Au nanoparticle/MWNT hybrid materials is developed. The Au nanoparticles are prepared by reducing AuCl(4)(-) with citrate and attached to thiol-modified MWNTs. Owing to the reducing property and the binding ability to Mn-containing species of capping agents surrounded the Au nanoparticles, the MnO(2) nanosheets are formed on the surface of Au nanoparticles. The ternary nanocomposites of MnO(2)/Au/MWNT have been characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and FT-IR spectroscopy. The affiliation of MnO(2) nanosheets into the hybrids remarkably enhances the electrocatalytic performance of Au nanoparticle/MWNT towards the oxygen reduction reaction. The specific capacitance of the ternary hybrids is also increased dramatically comparing with that of Au/MWNT.