Hydrothermal Synthesis Technique Research Articles

Mo-doping induced edge-rich cobalt iron oxide ultrathin nanomeshes as efficient bifunctional electrocatalysts for overall water splitting

Exploring earth-abundant and extremely active bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential and challenging for practical application of overall water splitting. Enriching edge defects is proven a remarkably effective strategy to enhance the exposure of active sites and thus improve the electrocatalytic performance. This paper reports an edge-rich Mo-doping cobalt iron oxide nanomeshes (NMs) vertically supported on nickel foam (NF) by means of the straightforward hydrothermal synthesis technique. The synthesized Co1Fe1Mo1.8O NMs@NF exhibits an outstanding OER performance with super low overpotential of 210 mV and HER activity with low overpotential of 157 mV to reach the current density of 10 mA cm−2, as well as long-term cycle durability after 24 h. Significantly, as a bifunctional electrode, Co1Fe1Mo1.8O NMs@NF displays a low potential of 1.68 V to reach 10 mA cm−2 coupled with a long-term water splitting stability in an alkaline electrolyte. This work may pave the way to a rational design of prospective bifunctional electrocatalysts for practical applications of electrochemical process.

Direct synthesis of Cerium(Ⅳ)-Incorporated mesostructured cellular foam for immobilization of penicillin G acylase

Cerium-incorporated mesostructured cellular foams (Ce-MCF) as a novel support has been synthesized successfully for immobilizing penicillin G acylase (PGA) through a Lewis acid-base interaction. The PGA was firmly immobilized on Ce-MCF by interacting with the surface robust Lewis acid sites due to the incorporation of Ce, which is the essence of this immobilization method. The Ce-MCF support was synthesized through the direct hydrothermal synthesis technique with citric acid complexant and categorized by XRD, SAXS, nitrogen sorption, XPS, TEM , and pyridine-IR. The results showed that the Ce-MCF samples had ordered long-range structure, large pore diameter, large specific surface area, pore-volume, narrow pore diameter distribution and strong Lewis acid site. According to the results, the PGA/Ce-MCF has high enzymatic activity and improved operational stability greatly. The PGA/Ce-MCF's initial enzymatic activity remains 10,573 U/g to hydrolyze penicillin G potassium salt, similar with that of PGA/Si-MCF. In addition, the Ce-MCF samples have much higher operational stability than PGA/Si-MCF. Followed by recycling for 10 times, PGA/Ce-MCF preserves 90% of its primary enzymatic activity, which is much higher than 77% of PGA/Si-MCF. A novel immobilization method has been developed for penicillin G acylase (PGA) by a Lewis acid-base interaction. The essence of this method lies in utilization of a Ce-MCF (mesostructured cellular foam) nanoporous material. The cerium incorporated into the framework of MCF can significantly enhance the Lewis acidity of MCF. The high operational stability and enzymatic activity of PGA/Ce-MCF achieved during the hydrolysis of penicillin G potassium salt, suggesting that the enzymes can be firmly immobilized by the Lewis acid sites whilst retaining high activity. • PGA can be firmly immobilized on Ce-MCF by the Lewis acid sites whilst retaining high activity. • After recycled for 10 times, PGA/Ce-MCF retains 90% of its initial enzymatic activity, much higher than 77% of PGA/Si-MCF. • The cerium incorporated into the framework of MCF can significantly enhance the Lewis acidity of MCF. • The Ce-MCF support was synthesized by a pH-adjusting hydrothermal synthesis method with addition of citric acid.

Preparation and Evaluation of Nanocomposite Sodalite/α-Al2O3 Tubular Membranes for H2/CO2 Separation

Nanocomposite sodalite/ceramic membranes supported on α-Al2O3 tubular support were prepared via the pore-plugging hydrothermal (PPH) synthesis protocol using one interruption and two interruption steps. In parallel, thin-film membranes were prepared via the direct hydrothermal synthesis technique. The as-synthesized membranes were evaluated for H2/CO2 separation in the context of pre-combustion CO2 capture. Scanning electron microscopy (SEM) was used to check the surface morphology while x-ray diffraction (XRD) was used to check the crystallinity of the sodalite crystals and as-synthesized membranes. Single gas permeation of H2, CO2, N2 and mixture gas H2/CO2 was used to probe the quality of the membranes. Gas permeation results revealed nanocomposite membrane prepared via the PPH synthesis protocols using two interruption steps displayed the best performance. This was attributed to the enhanced pore-plugging effect of sodalite crystals in the pores of the support after the second interruption step. The nanocomposite membrane displayed H2 permeance of 7.97 × 10−7 mol·s−1·m−2·Pa−1 at 100 °C and 0.48 MPa feed pressure with an ideal selectivity of 8.76. Regarding H2/CO2 mixture, the H2 permeance reduced from 8.03 × 10−7 mol·s−1·m−2·Pa−1 to 1.06 × 10−7 mol·s−1·m−2·Pa−1 at 25 °C and feed pressure of 0.18 MPa. In the presence of CO2, selectivity of the nanocomposite membrane reduced to 4.24.

Tunable luminescence from yttrium oxide flowers using asparagine as shape modifier

A series of Eu3+/Nd3+/Yb3+ co-doped Y2O3 flowers with different Nd3+ concentrations are synthesized using asparagine as a complexing ligand by low-temperature hydrothermal synthesis technique. The cubic crystal structure and flower like architecture morphology of the annealed co-doped Y2O3 phosphors at different synthesis temperatures have been confirmed from XRD and FESEM analysis. The photoluminescence study of the developed phosphors has been performed by using excitations at 220 nm, 808 nm and 980 nm, and the responsible mechanisms have been discussed in detail. Dipole-dipole interaction is found responsible for concentration quenching with inter-ionic separation ∼15.27 Å among the Nd3+ ions. Asymmetric ratio is calculated to be 3.01 with respective to Eu3+ ions in co-doped Y2O3 host lattice. The spectral characteristics have been described via nephelauxetic ratio and Judd–Ofelt parameters in co-doped Y2O3 under UV excitation. Two photon process dominates the upconversion luminescence on 808 nm irradiation. CIE color coordinates clearly indicates that co-doped Y2O3 phosphors can be further used for multi-color labeling applications. Moreover, because of the intrinsic magnetic moment of Nd3+ ions, the developed Eu3+/Nd3+/Yb3+ co-doped Y2O3 phosphors exhibit paramagnetic behavior with magnetization value 0.0064 emu/g at 300 K.

Cost-effective single-step synthesis of flower-like cerium-ruthenium-sulfide for the determination of antipsychotic drug trifluoperazine in human urine samples

Nanostructured binary metal sulfides are considered as a promising electrode material because of their excellent electron transfer and good sensing behavior rather than metal oxides. As a result, the binary metal sulfides were applied in energy and electrochemical sensor applications. Herein, we propose the electrochemical sensor method based on flower-like cerium-ruthenium sulfide nanostructure (Ce–Ru–S NS) for the electrochemical sensing of trifluoperazine (TFPZ). The Ce–Ru–S NS prepared using the cost-effective one-pot hydrothermal synthesis technique. Then, the resultant materials were characterized through suitable spectrophotometric techniques and the electrocatalytic properties of the fabricated sensor were investigated by EIS, CV, and amperometric (i–t) techniques. The Ce–Ru–S material has good electrocatalytic activity towards the electrochemical oxidation of TFPZ. Significantly, the fabricated sensor demonstrates the distinct amperometric response with the lowest limit of detection (LOD) of 0.322 nM (S/N = 3), high sensitivity 2.682 μA μM−1 cm−2 and lowest oxidation potential of +0.64 V (Ag/AgCl). Furthermore, the Ce–Ru–S NS displays excellent selectivity, good reproducibility, and long-term stability. The practicability of the TFPZ sensor tested in a human urine sample.

Fabrication of Porous Configurated Ni2P/Ni Foam Catalyst and its Boosted Properties for pH‐universal Hydrogen Evolution Reaction and Efficient Nitrate Reduction

AbstractNickel phosphide (Ni2P) has been widely explored toward hydrogen evolution reaction (HER) for desirable durability and high performance. Tuning the electronic structures and morphologies of Ni2P plays a pivotal role in the improvement of HER performance. In this work, three Ni2P catalysts were fabricated by different strategies and their HER properties were compared. It was found that the bicontinuous porous structured Ni2P on Ni foam (Ni2P /NF−EHP) prepared using coupled electroless nickel‐phosphorus (Ni−P) plating, hydrothermal synthesis and low temperature phosphorization techniques, exhibits the best catalytic activity and a wide pH adaptability. The overpotential at 10 mA cm−2 and Tafel slope are 78 mV and 33 mV dec−1 in 0.5 M H2SO4, those in 1 M PBS are 125 mV and 93 mV dec−1, and 101 mV and 76 mV dec−1 in 1 M KOH. Additionally, the Ni2P/NF−EHP‐catalyzed HER process is also applicable for nitrate reduction with a remarkable removal efficiency of 92.6 %. This catalyst also exhibits a desirable durability both in HER and nitrate reduction. This work offers an efficient strategy to exploit compatible pH‐universal HER catalysts, explores the engineering application of HER process in nitrate reduction.

Synthesis of Y<sub>2</sub>O<sub>3</sub>: Eu Nanosized Phosphor Using Hydrothermal Technique and Rapid Thermal Annealing (RTA)

The application of special nanomaterials is promising for the development of new methods for the diagnostics and treatment of cancer. Photodynamic therapy (PDT) is a well-known and recognized method of cancer treatment. This type of therapy is less carcinogenic and mutagenic compared to radiation and chemotherapy, since the applied photosensitizers do not bind to DNA of the cells. However, currently this technique is only applicable to skin cancer, while its extension to the treatment of abdominal tumors requires the creation of pharmacological drugs for PDT, which along with a photosensitizer include a colloidal solution of nanosized luminescent phosphor emitting visible light with the required wavelength under the influence of infrared, X-ray or γ-radiation, which easily penetrates the body tissues. Since photosensitizers are already available as commercial products, the most important goal is the development of nanosized phosphors providing the required radiation convertion. In this study, the effects of hydrothermal synthesis, duration and the conditions of rapid thermal annealing (RTA) on Y2O3:Eu phosphor particle size were studied. The hydrothermal synthesis technique was carried out in two ways: chloride (precipitation from a chloride solution using NaOH and NH4OH precipitators) and acetate (decomposition of mixed acetate either without a dispersant at 230° C for 24 hours, or using PEG-200 and PEG-2000 as dispersants at 230 °C for 12 hours). The rapid thermal annealing was performed either at 600 °C for 20 minutes, or at 800 °C for 5 minutes. The developed synthetic approaches afforded Y2O3:Eu nanosized phosphor samples with the particle size not exceeding 200 nm.

Multi-component nanocomposite infrared flare with superior infrared signature via synergism of nanothermite and reduced graphene oxide

Infrared-guided missiles caused 90% aircraft damage. Infrared decoy flares are effective counter measure against infrared missiles. Decoy flare thermal signature depends mainly on black body emission of carbonaceous combustion products. Thermite particles can offer substantial heat output to promote black body emission. Reduced graphene oxide (RGO) is a promising material for advanced infrared decoy flares. RGO could act as ideal black-body emitter with superior thermal properties and high interfacial surface area. This study is dedicated to investigate novel synergism between Fe2O3 and RGO; Fe2O3 NPs of 3.56 nm were fabricated using hydrothermal synthesis technique. RGO nano-sheets of 10 µm dimensions and 10 nm thickness were developed via the reduction of graphene oxide, developed by Hummer method. Complete reduction of GO to RGO was confirmed by Raman spectroscopy. Amorphous nano-sheets structure was observed using TEM; XRD diffractogram demonstrated tiny characteristic broad peak for amorphous RGO. Decoy flare formulation based on Fe2O3, RGO, reactive metal fuel (Mg), and fluorocarbon polymer (teflon) were developed. Thermal signature was evaluated using Arc-Optics IR spectrometer (1–6 µm). Multi-component MTV nanocomposite flare based on 6 wt % RGO and 2 wt % Fe2O3 demonstrated superior spectral and radiometric performance. It offered an increase in average intensity by 130% to reference MTV formulation; additionally it offered superior relative intensity Ɵ value of 0.76. While RGO could act as novel black body emitter; thermite reaction between Fe2O3 NPs and surplus magnesium fuel could provide substantial heat output; that could promote RGO black body emission.

The hydrothermal synthesis and RTA conditions influence on the Y2O3:Eu nanosized phosphors microstructure

When developing new methods for the diagnosis and treatment of cancer, the use of nanomaterials may be promising. One of the ways to improve and expand the fields of application of radiation and photodynamic therapy of cancer is the use of drugs containing nanosized phosphors. The aim of the work was to study the effect of the duration of hydrothermal synthesis and the conditions of rapid thermal annealing (RTA) on the Y2O3:Eu nanosized phosphors microstructure. The hydrothermal synthesis technique was carried out in two ways: chloride (precipitation from a chloride solution using NaOH and NH4OH precipitators) and acetate (decomposition of mixed acetate without a dispersant, as well as with PEG-200 and PEG-2000 dispersants). Hydrothermal synthesis was carried out at a temperature of 230 °C for 6–24 hours. Rapid thermal annealing was carried out at a temperature of 600–800 °C for 5–20 minutes. As a result of our work, the Y2O3:Eu nanosized phosphors which particle size does not exceed 200 nm is synthesized.

Hydrothermal Synthesis of Polyoxometalate Containing Cobalt Ion, and Its Polyurethane Composites for Dielectric Material Applications

ABSTRACT Polyurethane (PU) composites were prepared with different diisocyanate and diol compounds by adding cobalt ion-based polyoxometalate (Co-POM) as reinforcement. For the determination of using potential in microelectronic applications, the dielectric behavior and dielectric constant of these PU composites were investigated and compared to pure polyurethane structures. For this aim, firstly, Co-POM with Keggin structure was obtained from ammonium heptamolybdate, 1,10-phenanthroline ligand and a cobalt (II) salt by hydrothermal synthesis technique. Then, polyurethane/Co-POM composites (PU/Co-POM) were prepared with ethylene glycol, nonaromatic diisocyanate and different amounts of Co-POM reinforcement (1%, 3%, 5% and 10%, w/w) by in situ polymerization and mix-blend technique. Obtained PU/Co-POM composites were characterized in detail by infrared spectroscopy, Elemental Mapping, Energy-dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD) spectroscopy. The surface structure, morphology and roughness of PU/Co-POM composites were investigated by SEM and AFM analysis. The elemental maps of the PU/Co-POM surface were examined by EDX elemental mapping analysis methods. Thermal stability, Tg values and thermal decomposition temperatures of PU/Co-POM structures were determined by different thermal analysis techniques. Thermal analysis results showed that the PU/Co-POM composites are thermally stable up to approximately 200°C and Tg values of synthesized PU composites are seen between 54.72°C and 75.15°C. The dielectric properties and dielectric constants of the PU/Co-POM composites were determined in the frequency range 1 Hz to 1000 kHz at room temperature using impedance analyzer. Dielectric constants of these composites were ranged from 5.50 to 9.26 according to their polarizability and H-bonding ability of PU matrix structure. According to the dielectric measurements, the dielectric constants of the PU/Co-POM structures were significantly decreased compared to the pure PU structures.

Synthesis and characterization of heterogeneous ZnO/CuO hierarchical nanostructures for photocatalytic degradation of organic pollutant

In the current study, ZnO, CuO and ZnO/CuO mixed metal oxide nano-composites with different molar ratio of Zn/Cu (10:1, 8:1, 6:1, 4:1, 2:1) were prepared via low temperature hydrothermal synthesis technique. The consequences of different synthesis conditions such as molar ratio, pH and processing temperature on physicochemical properties of ZnO/CuO nano-composites were also studied. The surface morphology, elemental composition, crystal structure, chemical states and optical characteristics of the prepared nano-composite materials were determined using various techniques such as field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), X-ray diffraction analysis (XRD), X-ray photo-electron spectroscopy (XPS) and UV–visible diffused reflectance spectra (UVDRS). A morphological change in bitter gourd structured ZnO as well as improved optical response of ZnO after incorporation of CuO was observed. The decreased recombination rate of charge carriers, effectual generation of photoinduced charge carriers, formation of hetero-junction system and unique morphology are the responsible factors for improved photodegradation characteristics of prepared ZnO/CuO nano-composites. Role of active species and pH of dye solution in degradation process was also studied.

Construction of scaffold-like Au@MoS2/Bi2S3 networks with superior electro-catalytic performance

Abstract In order to improve the electrocatalytic hydrogen evolution reaction (HER), semiconductor heterojunctions must be further developed. In the present investigation, three-dimensional scaffold-like networks, consisting of gold (Au), bismuth sulfide (Bi2S3), and molybdenum disulfide (MoS2), have been developed and constructed. The main purpose was to improve the HER performances of a MoS2-based material. A MoS2/Bi2S3 heterostructure was, at first, prepared by using a hydrothermal synthesis technique and a Bi2WO6 precursor. The resulting MoS2/Bi2S3 network was found to exhibit a disk-like morphology with a homogeneous scaffold structure. The Au@MoS2/Bi2S3 ternary composite structure was, thereafter, synthesized by depositing Au nanoparticles on the MoS2/Bi2S3 heterostructure. As a result of the following HER measurement, the onset overpotential of Au@MoS2/Bi2S3 was observed to decrease to 72 mV, and the Tafel slope decreased to 40 mV/dec. The three different materials (within Au@MoS2/Bi2S3) were found to contribute to these positive results. The Bi2S3 structure promoted the electronic charge transport, while the dispersed MoS2 structure exposed more active sites. Furthermore, the deposited Au nanoparticles promoted the conduction of electrons from the nanoparticles to the hydrogen carriers and were also found to accelerate the complete HER process (by reducing the activation energy of HER). Owing to these excellent catalytic performances, the here presented results will aid in the construction of a composite semiconducting material with improved electrocatalytic performances.

Template-free microwave-assisted hydrothermal synthesis of manganese zinc ferrite as a nanofertilizer for squash plant (Cucurbita pepo L)

Manganese, zinc, and iron are the most essential micronutrients required for plant growth and applied as foliar fertilizers. Herein, a simple template-free microwave-assisted hydrothermal green synthesis technique was adapted to produce manganese zinc ferrite nanoparticles (Mn0.5Zn0.5Fe2O4 NPs) at different temperatures (100, 120, 140, 160 and 180 °C). The prepared nanomaterials were employed at different concentrations (0, 10, 20, and 30 ppm) as foliar nanofertilizers during the squash (Cucurbita pepo L) planting process. X-ray diffraction patterns of the prepared nanomaterials confirmed successful production of the nanoferrite material. The prepared nanofertilizers showed type IV adsorption isotherm characteristic for mesoporous materials. FE-SEM and HR-TEM imaging showed that the nanoparticles were cubic shaped and increased in particle size with the increase in microwave temperature during production. The impact of application of the synthesized ferrite nanoparticles on vegetative growth, proximate analysis, minerals content and the yield of squash plant was investigated for two consecutive successful planting seasons. The nanoferrite synthesized at 160 °C and applied to the growing plants at a concentration of 10 ppm gave the highest increase in % yield (49.3 and 52.9%) compared to the untreated squash for the two consecutive seasons, whereas the maximum organic matter content (73.0 and 72.5%) and total energy (260 and 258.3 kcal/g) in squash leaves were obtained in plants treated with 30 ppm ferrite nanoparticles synthesized at 180 °C. On the other hand, the maximum organic matter content (76.6 and 76.3%) and total energy (253.6 and 250.3 kcal/g) in squash fruits were attained with plants supplied by 20 ppm ferrite nanoparticles synthesized at 160 °C. These results indicate that the simple template-free microwave-assisted hydrothermal green synthesis technique for the production of manganese zinc ferrite nanoparticles yields nanoparticles appropriate for use as fertilizer for Cucurbita pepo L.

Facile one-step hydrothermal synthesis and room-temperature NO2 sensing application of α-Fe2O3 sensor

An alpha-iron oxide (α-Fe2O3) film-sensor prepared by a simple one-step hydrothermal synthesis technique demonstrates a high selectivity and sensitivity toward NO2 at room-temperature (27 °C). The XRD pattern of the as-synthesized sensor endows polycrystalline nature and hematite crystal structure. The gas sensing properties of α-Fe2O3 sensor are investigated against various target gases viz. hydrogen (H2), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon dioxide (CO2), liquefied petroleum gas (LPG), and carbon monoxide (CO). Due to a high specific surface area, special structure, and high electron contributing power over other tested gases, α-Fe2O3 sensor exhibits a high response, with good response/recovery time for NO2 gas. The α-Fe2O3 sensor shows 86% response for 100 ppm concentration of NO2 gas with excellent response/recovery time (31/32 s) and reported. The α-Fe2O3 sensor performance is measured for various concentration levels of NO2 gas. The theoretically proposed gas sensing mechanism also suggests a better response of the α-Fe2O3 sensor to NO2 gas over other gases. The room-temperature sensing operation, high selectivity, moderate repeatability and short response/recovery time with cost-effectiveness followed scalable synthesis of α-Fe2O3 sensor would decidedly useful for social and commercial benefits.

Supercapacitor like behavior in nano-sized, amorphous mixed poly-anion cathode materials for high power density lithium and other alkali-metal ion batteries

In this manuscript, we report a new mixed poly-anionic framework based material as a cathode for lithium-ion batteries which is having an amorphous structure as compared to traditional crystalline nature of cathode materials, with a chemical formula of Na2Fe(PO4) (CO3). The amorphous mixed poly-anion cathode is synthesized using one-pot microwave hydrothermal synthesis technique, which is a faster and cheaper technique as compared to the traditional techniques of forming amorphous structures. The particle size of the material lies in the nano-regime, with a particle size distribution in the range of 10–80 nm. The amorphous structure, combined with the small particle size, shows excellent electrochemical properties as lithium-ion battery cathode. The half-cells are able to charge at constant specific current of 1 A g-1 (∼10C rate), and deliver an energy density of ∼150Whkg−1 at a specific discharge current of 50 mAg−1, consistently without fading. The cell is able to charge to ∼85% of its theoretical capacity in under 7 min with CC-CV charging scheme, and deliver the capacity at 50 mAg−1 specific discharge current (∼0.5C) with an efficiency >97% for ∼150 cycles, with ∼100% capacity retention. The high energy density and the anomalous charge-discharge profile of the material make it extremely suitable for next-generation supercapacitors as well.

Regulation of specific surface area of 3D flower-like WO3 hierarchical structures for gas sensing application

The 3D flower-like WO3 nanoparticles with hierarchical structures were synthesized via a hydrothermal synthesis technique by using NaHSO4 as a capping agent. It demonstrates that surface area of the synthesized WO3 products can be manipulated via adjusting concentration of the capping agent NaHSO4 alone. The contribution of alcohol is to construct hierarchical structures with large specific surface areas, while the effect of SO42− is to inhibit the growth rate in the thickness direction of nanosheets which are self-assembled as well to form hierarchical structures. In addition, the gas-sensing property of sensors fabricated by 3D flower-like hierarchical structured WO3 nanoparticles were carried out by detecting different volatile gases with a lower concentration. All the samples are sensitive to ethanol gas and the WO3 3D flowers synthesized by 12 g NaHSO4 exhibit the excellent gas-sensitive property due to the highest surface area, the sensitivity as high as 96 under the concentration of 35 ppm at the optimal temperature of 350 °C, which implies that this 3D hierarchical structured WO3 nanoparticles could be used as a high-efficiency sensor candidate materials for selective detection of ethanol.

A direct Z-scheme Bi2WO6/NH2-UiO-66 nanocomposite as an efficient visible-light-driven photocatalyst for NO removal.

To explore an efficient photocatalyst for NO pollution, a direct Z-scheme photocatalytic system is successfully fabricated by coupling Bi2WO6 with NH2-UiO-66 via a simple hydrothermal synthesis technique. The Z-scheme system promotes the NO photocatalytic oxidation activity with an optimum NO removal rate of 79%, which is 2.7 and 1.2 times that obtained by using only pristine Bi2WO6 and NH2-UiO-66, respectively. Simultaneously, superior selectivity for converting NO to NO3−/NO2− is observed. The enhanced photocatalytic performance of the Bi2WO6/NH2-UiO-66 hybrids is attributed to the following two aspects: (i) large specific area of NH2-UiO-66, which exposes more active sites and is beneficial to the adsorption and activation of NO; (ii) outstanding Z-scheme structure constructed between BiWO6 and NH2-UiO-66, which can improve the efficiency of the separation of electron–hole pairs and preserves the strong oxidation ability of hybrids. ESR analysis shows that ·O2− and ·OH contribute to NO removal. A possible photocatalytic mechanism of NO oxidation on the direct Z-scheme photocatalyst (BWO/2NU) under visible light irradiation is proposed. This work displays the BWO/2NU hybrid's potential for treating low-concentration air pollutants, and the proposed Z-scheme photocatalyst design and promotion mechanism may inspire more rational synthesis of highly efficient photocatalysts for NO removal.

Photoluminescent Investigation of the Doping Site of Eu3+-Doped [Zn3(BTC)2∙12H2O] Metal-Organic Framework Prepared by Microwave-Assisted Hydrothermal Synthesis

The [Zn3(BTC)2·12H2O] (BTC = 1,3,5-tricarboxylate) metal-organic framework (MOF) was successfully synthesized using a microwave-assisted hydrothermal synthesis technique, which allowed for significantly decreased reaction time compared to the production of the same compound via conventional heating. In situ doping with Eu3+ ions at concentrations ranging from 1.0 to 5.0 mol% produced doped materials whose emission ranged from blue to red color. The Eu3+ spectroscopic properties were used to study the incorporation of the dopant into the structure of [Zn3(BTC)2·12H2O], even at very low concentrations. These experiments confirmed the usefulness of this ion as a luminescent probe, as it permitted the identification of small variations in structure not perceptible by X-ray diffraction. The variation in the coordination environment induced by increases in doping percentage was analyzed by evaluating changes in the characteristic Eu3+ excitation and emission profiles, using them to calculate luminescence lifetimes, experimental intensity parameters Ωλ (λ: 2 and 4) as well as the intrinsic quantum yield (QEu+3Eu+3) of the 5D0 emitting level of each doped MOF. The excitation and luminescence spectra show that intramolecular energy transfer from the BTC linker to Eu3+ ion, and we could observe the emission color tuning originated from the emissions of the BTC ligand and Eu3+ ion.

Cytotoxic Effects of Granulated Hydroxyapatite with Various Particle Size Distribution

Hydroxyapatite-based materials show promise in such applications as reconstructive surgery, stomatology and cosmetology, they can also be used as components of toothpaste, disinfectant products and dietary supplements (DS). However, cytotoxicity of hydroxyapatite powders synthesized via various methods towards a variety of biological cells requires a thorough study.Cytotoxicity of hydroxyapatite powder samples with spherical particles in three size ranges: 5-25 μm, 25-45 μm and 40-125 μm, synthesized by hydrothermal synthesis with further ultrasonic and spray-drying treatment, was studied on human blood cells and on gram-negative bacteria E.coli.The examined hydroxyapatite samples have no toxic effect on human blood leukocytes (in concentration 40 mg per 1 ml H2O or normal saline) and on gram-negative bacteria E.coli. (in concentration 40 mg per 1 ml H2O or normal saline) regardless of the contact time and particle size. The obtained data demonstrate safety of the examined materials and absence of toxic effects towards the test objects. This allows us to regard the studied hydroxyapatite samples as biocompatible.The present study results could be used to develop products and medicinal drugs based on hydroxyapatite granules synthesized by means of hydrothermal synthesis technique with further sonication and spray drying.

Enhancing the specific capacity and rate performance of MoS2 nanomaterials via introducing subgrains at a hydrothermal temperature 160 °C

Reversible specific capacity and rate performance are required for MoS2 nanomaterials as lithium-ion batteries (LIBs) anodes. Here we reported a novel MoS2 structure with nano-size subgrain microstructure and thus enhanced electrochemical performance produced by a low-temperature hydrothermal synthesis technique. Ammonia solution treatment was proved feasible to remove the S22− and MoO3 impurities from the composite produces. After purification of the MoS2 prepared at a temperature of 160 °C, the (002) interlayer spacing was ~0.69 nm. In addition, the MoS2 sheets consisted of nano-size subgrains, with Mo enrichment at grain boundaries. As a result, a reversible specific capacity of 826 mAh g−1 at a current density of 0.1 A g−1 and rate performance of 700 mAh g−1 at 1 A g−1 were achieved. This shows that high purity MoS2 nanomaterials prepared via ammonia solution may act as promising materials for high performance anodes.