Glycol Mixed Solvent Research Articles

Constructing thin BiOCl nanoplates for highly efficient photocatalytic peroxymonosulfate activation: In-depth understanding of the activation process

Photocatalytic peroxymonosulfate (PMS) activation on semiconductors is attractive for remediation of wastewaters containing refractory organic pollutants because of the synergies between photocatalysis and PMS activation. However, the PMS activation route and the main reactive species are unclear and seek of highly active and stable catalysts is desirable. In this work, for the first time, BiOCl semiconductors with different morphologies are utilized for photocatalytic activation of PMS under simulated solar light to degrade carbamazepine (CBZ). Thin BiOCl nanoplates synthesized in water/ethylene glycol mixed solvents exhibit superior performances with high activities, good applicability in a wide pH range and excellent stability. The addition of PMS can dramatically accelerate (2.5 times higher) the CBZ degradation rate compared with the photocatalysis on BiOCl. The possible activation routes are carefully discussed. PMS is predominantly activated by the photo-generated electrons, not the O2− and not the holes. Serving as an electron acceptor, PMS can effectively consume electrons to inhibit the recombination of electron-hole pairs, weaken the photo-etching of BiOCl and generate additional SO4−/HO to facilitate CBZ degradation. Rather than the SO4−/HO generated from PMS, O2− and holes produced from photocatalysis are the main reactive species to dominate the degradation. The main function of PMS is to improve the intrinsic photocatalytic performance of BiOCl. This work reveals the activation route of PMS and the realistic function of PMS in photocatalysis, which would be valuable for understanding the mechanism of photocatalytic PMS activation and for designing efficient catalysts.

Facile Hydrothermal Synthesis and Supercapacitor Performance of Mesoporous Necklace-Type ZnCo2O4 Nanowires

In this work, mesoporous ZnCo2O4 electrode material with necklace-type nanowires was synthesized by a simple hydrothermal method using water/ethylene glycol mixed solvent and subsequent calcination treatment. The ZnCo2O4 nanowires were assembled by several tiny building blocks of nanoparticles which led to the growth of necklace-type nanowires. The as-synthesized ZnCo2O4 nanowires had porous structures with a high surface area of 25.33 m2 g−1 and with an average mesopore of 23.13 nm. Due to the higher surface area and mesopores, the as-prepared necklace-type ZnCo2O4 nanowires delivered a high specific capacity of 439.6 C g−1 (1099 F g−1) at a current density of 1 A g−1, decent rate performance (47.31% retention at 20 A g−1), and good cyclic stability (84.82 % capacity retention after 5000 cycles). Moreover, a hybrid supercapacitor was fabricated with ZnCo2O4 nanowires as a positive electrode and activated carbon (AC) as a negative electrode (ZnCo2O4 nanowires//AC), which delivered an energy density of 41.87 Wh kg−1 at a power density of 800 W kg−1. The high electrochemical performance and excellent stability of the necklace-type ZnCo2O4 nanowires relate to their unique architecture, high surface area, mesoporous nature, and the synergistic effect between Zn and Co metals.

Assembly behaviour and thermodynamics of the mixture of cetyltrimethylammonium bromide and bovine serum albumin in aqueous and aqua-ethylene glycol mixed solvents media at several temperatures

The aggregation of the mixture of cetyltrimethylammonium bromide (CTAB) and bovine serum albumin (BSA) in aqueous and aq. ethylene glycol (EG) media has been carried out conductometrically at numerous temperatures. Conductivity values of CTAB have been changed with the concentration of CTAB and the values also experience a change with the presence of BSA, change of BSA concentration, variation of EG contents as well as the experimental temperatures. The critical micelle concentration (CMC) and the extent of micelle dissociation (α) were evaluated graphically plotting the specific conductivity against the CTAB concentration. The CTAB aggregation happens lately in the appearance of BSA. Also, the CMC values of CTAB + BSA experience an upsurge with the rise of BSA contents. The CMC values of the mixture of CTAB and BSA have been obtained to be higher in extents in aq. EG solution in contrast to water medium. In all of the circumstances inspected, the micellisation of the CTAB + BSA mixture is spontaneous (negative ΔG 0 m values). Depending on the ΔH0 m and ΔS0 m values for the CTAB + BSA mixture, the recommended forces between CTAB and BSA are electrostatic interaction (hydrogen bonding and ion-dipole interactions) and hydrophobic interactions.

SYNTHESIS OF CHALCOPYRITE CuInSe2 (CIS) NANOSHEETS USING VITAMIN C AS AN ADJUVANT AND PHOTOELECTRIC PROPERTIES OF CIS THIN FILMS

To prepare chalcopyrite-phase CuInSe2 (CIS) nanosheets, green reductants were screened by using them to reduce the valence state of copper sources using a N,N-dimethylformamide/triethylene glycol(DMF/TEG) mixed solvent. CuCl was used as the copper source, indium chloride as the indium source, selenium powder as the selenium source, TEG as the anionic solvent, DMF as the cationic solvent, and Vitamin C (Vc) as the reductant. The influences of reaction temperature, reaction time, and Vc amount on the phase and composition of synthetic CuInSe2 nanosheets were examined, and the results were used to propose a reaction mechanism. The optional reaction conditions were a reaction temperature of 260 oC, a reaction time of 16 h, and a Vc amount of 0.20 g. Chalcopyrite-phase CIS nanosheets were synthesized with particle sizes of 14 µm and a uniform particle size distribution. CuInSe2 thin films displayed good surface smoothness and compactness in a 5.5 µm spin-cast film. The thin film showed a bandgap of 1.08 eV, a carrier concentration of 5.26×1016 cm-3 , and a carrier mobility of 150.41 cm2 V -1 S -1 . The results showed that this strategy can be used to prepare chalcopyrite-phase CIS which could be used as a photosensitive layer for various optoelectronic devices.

Hierarchical Co–Mo–S nanoflowers as efficient electrocatalyst for hydrogen evolution reaction in neutral media

The development of hydrogen evolution reaction (HER) catalysts composed of inexpensive and abundant elements is an effective strategy to realize the hydrogen economy, particularly in neutral media. Herein, we report the design and synthesis of a series of hierarchical Co–Mo–S nanoarchitectures by a facile and efficient hydrothermal method in a water-ethylene glycol mixed solvent system. Such as-synthesized bimetallic sulfide samples as HER electrocatalysts exhibit good performance in phosphate buffer solution (1 M PBS), especially Co–Mo0.4-S nanocomposite (0.4 is the molar number of Na2MoO4·2H2O adding in the experimental section) shows the highest activity for HER. Co–Mo0.4-S only requires an overpotential of 213 mV to reach 10 mA cm−2 with 94 mV dec−1 of Tafel slope, which outperforms those of Co–S (455 mV) and Mo–S (>500 mV). The excellent HER performance of Co–Mo0.4-S electrocatalyst can be attributed to the strong electronic interactions of Co–S and Mo–S, the improvement electrical conductivity and the high specific surface. In addition, such a Co–Mo0.4-S nanoflower may be employed as a promising non-precious electrocatalyst for HER to substitute the Pt/C material in neutral media.

Uniform Li1.2Ni0.13Co0.13Mn0.54O2 hollow microspheres with improved electrochemical performance by a facile solvothermal method for lithium ion batteries

Here, we designed a facile solvothermal method to prepare Li1.2Ni0.13Co0.13Mn0.54O2 hollow microspheres with considerable uniformity and monodispersity. In this method, lithium ions and transition metal carbonate have been simultaneously precipitated in the ethanol-polyethylene glycol mixed solvent system to form carbonate precursors, which subsequently transform into self-assembled hollow microspheres by a heat treatment. As cathode material for lithium ion batteries, its unique structure makes for sufficient contact between electrode and electrolyte to provide more reaction sites and shorter paths for Li+ transportation, contributing to remarkable cycling stability and excellent rate capability with improved electrochemical kinetics properties. Specifically, Li1.2Ni0.13Co0.13Mn0.54O2 hollow microspheres achieve a high initial discharge capacity of 287 mAh g−1 at 0.1 C and 234 mAh g−1 at 1 C, with capacity retentions of 85.7% and 81.3% after 100 cycles, respectively. Besides, it exhibits a high rate capacity of 150 mAh g−1 even at 5 C. Moreover, the present synthesis method could also provide an effective and promising strategy for the preparation of high energy density cathode materials for lithium ion batteries.

Microwave-assisted polyol synthesis of LiMnPO4/C and its use as a cathode material in lithium-ion batteries

We synthesized LiMnPO4/C with an ordered olivine structure by using a microwave-assisted polyol process in 2:15 (v/v) water–diethylene glycol mixed solvents at 130°C for 30min. We also studied how three surfactants—hexadecyltrimethylammonium bromide, polyvinylpyrrolidone k30 (PVPk30), and polyvinylpyrrolidone k90 (PVPk90)—affected the structure, morphology, and performance of the prepared samples, characterizing them by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, charge/discharge tests, and electrochemical impedance spectroscopy. All the samples prepared with or without surfactant had orthorhombic structures with the Pnmb space group. Surfactant molecules may have acted as crystal-face inhibitors to adjust the oriented growth, morphology, and particle size of LiMnPO4. The microwave effects could accelerate the reaction and nucleation rates of LiMnPO4 at a lower reaction temperature. The LiMnPO4/C sample prepared with PVPk30 exhibited a flaky structure coated with a carbon layer (∼2nm thick), and it delivered a discharge capacity of 126mAh/g with a capacity retention ratio of ∼99.9% after 50 cycles at 1C. Even at 5C, this sample still had a high discharge capacity of 110mAh/g, demonstrating good rate performance and cycle performance. The improved performance of LiMnPO4 likely came from its nanoflake structure and the thin carbon layer coating its LiMnPO4 particles. Compared with the conventional polyol method, the microwave-assisted polyol method had a much lower reaction time.

Template-free synthesis of In2O3 nanoparticles and their acetone sensing properties

Ordered In2O3 nanoparticles (In2O3 NPs) were successfully prepared via a template-free method. The synthesis was conducted in a water-glycerol-ethylene glycol mixed solvent without any templates, and the ultra-fine nanostructured In2O3 has a uniform size of about 20–30nm. The In2O3 nanoparticles exhibited improved sensitivity, fast response, and high selectivity to acetone. The enhanced acetone performance results from a large surface area with enough sensing active sites, and small particle size for effective electron depletion.

The fabrication of hollow magnetite microspheres with a nearly 100% morphological yield and their applications in lithium ion batteries

Abstract Hollow Fe 3 O 4 (H-Fe 3 O 4 ) microspheres were fabricated through a facile one-step solvothermal synthesis, which was performed in an ethylene glycol (EG)–diethylene glycol (DEG) mixed solvent using polyethylene glycol (PEG) as the stabilizer. The addition of DEG increased the viscosity of the system, which caused the Fe 3 O 4 primary crystal to aggregate slower and the morphological yield to approach nearly 100%. The as-prepared hollow Fe 3 O 4 microspheres show promise for application in lithium ion battery anodes and showed a reversible specific capacity of 453.3 mAh g −1 after 50 cycles at 100 mA g −1 .

A facile controlled in-situ synthesis of monodisperse magnetic carbon nanotubes nanocomposites using water-ethylene glycol mixed solvents

Abstract In this paper, a facile and controllable method for in-situ synthesis of the magnetic carbon nanotubes nanocomposites (Fe/CNTs) in water-ethylene glycol (EG) mixed solvents is reported by the deposition–precipitation method following annealing. The effect of water/EG ratio on the physico-chemical properties of magnetic Fe/CNTs is investigated by X-ray diffraction, transmission electron microscope, scanning electron microscopy, thermogravimetric analysis and physical property measurement system. The results indicate that the iron particle size distribution and grain size can be well-tuned by adjusting the water/EG ratio. With the variation of EG fraction in the mixed solvent, the nucleation, growth and crystallization of magnetic iron oxides with a controllable morphologies and particle sizes attached on the exterior surface of CNTs can be achieved. The as-prepared Fe/CNTs nanocomposites display superparamagnetic property at room temperature and the water/EG ratio determines the magnetization of the sample. Possible formation mechanism for magnetic Fe/CNTs is proposed based on the characterization results.

One-Pot Synthesis of Copper Sulfide Nanowires/Reduced Graphene Oxide Nanocomposites with Excellent Lithium-Storage Properties as Anode Materials for Lithium-Ion Batteries.

Copper sulfide nanowires/reduced graphene oxide (CuSNWs/rGO) nanocompsites are successfully synthesized via a facile one-pot and template-free solution method in a dimethyl sulfoxide (DMSO)-ethyl glycol (EG) mixed solvent. It is noteworthy that the precursor plays a crucial role in the formation of the nanocomposites structure. SEM, TEM, XRD, IR and Raman spectroscopy are used to investigate the morphological and structural evolution of CuSNWs/rGO nanocomposites. The as-fabricated CuSNWs/rGO nanocompsites show remarkably improved Li-storage performance, excellent cycling stability as well as high-rate capability compared with pristine CuS nanowires. It obtains a reversible capacity of 620 mAh g(-1) at 0.5C (1C = 560 mA g(-1)) after 100 cycles and 320 mAh g(-1) at a high current rate of 4C even after 430 cycles. The excellent lithium storage performance is ascribed to the synergistic effect between CuS nanowires and rGO nanosheets. The as-formed CuSNWs/rGO nanocomposites can effectively accommodate large volume changes, supply a 2D conducting network and trap the polysulfides generated during the conversion reaction of CuS.

Enhanced electrochemical performance of LiMnPO4/C prepared by microwave-assisted solvothermal method

An LiMnPO4/C composite material with ordered olivine structure was synthesized by a microwave-assisted solvothermal process in 2:5 (v/v) water-diethylene glycol mixed solvents at 190°C for 5min. The sample was characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, charge/discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy. The prepared LiMnPO4/C particles exhibited an irregular flaky form coated with a uniform carbon layer (approximately 2–3nm thick). The prepared LiMnPO4/C composite exhibited a discharge capacity of 131.4 and 85.2 mAh·g−1 at 0.1C and 5C, respectively. It delivered a discharge capacity of 109.2 mAh·g−1 with a capacity retention ratio of approximately 99% after 50 cycles at 1C. Furthermore, this microwave-assisted solvothermal approach led to a significant decrease in the reaction time as compared to conventional hydrothermal/ solvothermal processes.

Facile, one-pot solvothermal method to synthesize ultrathin Sb2S3 nanosheets anchored on graphene.

Ultrathin, two-dimensional (2D) nanosheets of layered transition-metal chalcogenides are theoretically and technologically intriguing. However, it still remains a great challenge to synthesize ultrathin nanosheets because of the lack of an intrinsic driving force for the anisotropic growth of 2D superposed microstructures. Here we demonstrate, for the first time to our knowledge, the in situ synthesis of large-scale ultrathin Sb2S3 nanosheets on graphene sheets (G) by solvothermal method in a water-ethylene glycol mixed solvent. Owing to the synergetic chemical coupling effects between G and Sb2S3, Sb2S3-G hybrid nanosheets exhibit high catalytic performance for the degradation of methylene blue in the presence of H2O2. Moreover, it was found that the resulting Sb2S3-G shows good electrocatalytic activity towards hydrazine oxidation. This work not only offers a low-cost and high performance alternative technology for synthesizing sheet-like Sb2S3, but also opens the door toward the fabrication of varying types of metal sulfide-graphene nanomaterials that will have wide applications in catalysis, environmental, and new energy fields.

Synthesis of copper sulfide nanowire bundles in a mixed solvent as a cathode material for lithium-ion batteries

Novel copper sulfide (CuS) nanowire bundles with a diameter of about 6 nm and a length up to several micrometers are successfully synthesized by a template- and surfactant-free method in a dimethyl sulfoxide (DMSO)-ethyl glycol (EG) mixed solvent. The resulting CuS nanowire bundles are used as a cathode material in lithium-ion batteries and exhibit a large capacity and excellent cycling stability and rate capability. The unique structure of the CuS nanowire bundles is responsible for their excellent electrochemical performance.

High-surface-area F-doped amorphous MoOx with high-performance lithium storage properties

In this work, we report the feasibility to achieve high lithium storage performance of MoOx by controlling its microstructure including specific surface area, doping, and amorphous structure. High-surface-area F-doped amorphous MoOx (a-MoOx) is synthesized by hydrothermal hydrolysis of ammonium molybdate tetrahydrate in a water–ethylene glycol (H2O–EG) mixed solvent. The resultant a-MoOx has a surface area as high as 212.74 m2 g−1 and exhibits a hierarchically microporous–mesoporous structure. The electrochemical measurements demonstrate that the high-surface-area F-doped a-MoOx exhibits high capacity and excellent electrochemical stability when used as an anode material for lithium-ion batteries. Some synergistic factors including F-doping, high specific surface area, and porous structure, may be responsible for the good lithium-storage performance.

Impact of reaction temperature, stirring and cosolvent on the solvothermal synthesis of anatase TiO2 and TiO2/titanate hybrid nanostructures: Elucidating the growth mechanism

One-dimensional anatase TiO2 and hybrid TiO2/titanate nanostructures are synthesized by a simple low temperature solvothermal route followed by the Na+/H+ ion-exchange and final calcination process. We investigated the impact of reaction temperature, stirring conditions and cosolvent on the morphologies of the as-prepared nanostructures. Nanotubes and nanorods are formed in alkaline solution, while nanorods/nanowires and nanoporous nanoribbons are formed in alkaline water–ethanol and alkaline water–ethylene glycol mixed solvents, respectively. X-ray diffraction, Raman scattering and high-resolution transmission electron microscopy studies are employed to identify the structure and phase composition. The formation of different morphologies of the as-synthesized nanostructures is investigated by field emission scanning electron microscopy and transmission electron microscopy. The growth mechanism and reaction process of the as-prepared nanostructures are explained based on the experimental observations. The photoluminescence, optical absorption and the tuning of band gap of the prepared samples are also studied. This work will be valuable for understanding the growth mechanism of various nanostructured TiO2 and to explore the commercial applications of nanoporous nanoribbons of TiO2.

Preparation and Recognized Characteristic of Histamine Molecularly Imprinted Polymers

HA MIP was prepared in acetonitrile-ethylene glycol mixed solvent ( 20:1，v/v), HA was used as the template, methacrylic acid (MAA) as the functional monomer, azobisisobutyronitrile (AIBN) as the initiator and ethylene glycol dimethaerylate (EGDMA) as the cross-linker. The UV spectrophotometry was used to demonstrate the interaction between HA and MAA. The adsorption characteristics of MIP to HA have been studied by equilibrium binding experiment and Scatchard analysis. The data obtained show that MIP reached equilibrium within 6 h. It is found that within the studied concentration range one HA molecule is entrapped by two MAA molecules The Scatchard chart shows the apparent maximum binding capacity (Bmax) and the dissociation contents (KD) of MIP are 170.5 μmol/g and 0.18 mmol/L, respctively. The MIP synthesized by this method have better binding ability to histamine and can be applied on the separation and detection of histamine.

The crystal structure and characterization of 2-D and 3-D indium phosphates synthesized from a water/ethylene glycol mixed-solvent system

Three indium phosphates [In16(HPO4)28(H2O)12](NH4)8(H2O)12 (1), [In2(OH)(HPO4)2(PO4)](H2O)(C6H18N2) (2) and [In3(HPO4)6](C2N2H10)(H3O)(H2O)2 (3) were solvothermally synthesized from water/ethylene glycol (EG) mixed solvent systems by using 1,3-propyldiamine (1,3-PDA), 2-methyl-pentamethylenediamine (MPMD) and diethylenetriamine (DETA) as structure directing agents (SDAs), respectively. Compound 1 consists of anionic layers of [In7(HPO4)14(H2O)6]7−, which are connected by InO6 octahedra to form an anionic three-dimensional (3-D) open framework with intersecting 12-membered rings channels. The channels are filled with charge-balancing ammonium cations and guest water molecules. Compound 2 possesses a 2-D layered structure consisting of anionic layers of [In2(OH)(HPO4)2(PO4)]2– formed by InO6 octahedra and PO4 tetrahedra, in which the protonated MPMD and water molecules lie between the layers. Compound 3 is constructed from a [3.3.3] propellane-like building unit made of strict alternation of InO6 octahedra and PO4H tetradedra, forming a 3-D open framework with intersecting 8- and 12-membered ring channels. The protonated water and ethylenediamine derived from the decomposition of DETA during the synthesis are located within the channels. The three compounds were characterized by powder X-ray diffraction (PXRD), single crystal X-ray diffraction, Fourier-transformed infrared (FT-IR) spectra, thermogravimetric analysis (TGA), inductively coupled plasma-atomic emission spectroscope (ICP-AES) and elemental analyses.

Solvothermal synthesis of Zn2GeO4:Mn2+ nanophosphor in water/diethylene glycol system

The influence of aging of the suspension containing the amorphous precusors on structural, compositional and photoluminescent properties is studied to understand the mechanism on the formation of Zn2GeO4:Mn2+ nanoparticles during the solvothermal reaction in the water/diethylene glycol mixed solvent. Aging at 200 °C for 20min forms the crystalline Zn2GeO4 nanorods and then they grow up to ∼ 50nm in mean length after aging for 240min. Their interplanar spacing of (410) increases with increasing the aging time. The photoluminescence intensity corresponding to the d–d transition of Mn2+ increases with increasing the aging time up to 120min, and then decreases after aging for 240min. The photoluminescence lifetime decreases with increasing the aging time, indicating the locally concentrated Mn2+ ions. These results reveal that Mn2+ ions gradually replace Zn2+ ions near surface through repeating dissolusion and precipitation processes during prolonged aging after the complete crystallization of Zn2GeO4.

Physicochemical Studies on the Interfacial and Micellization Behavior of CTAB in Aqueous Polyethylene Glycol Media

AbstractInterfacial and micellization behavior of cetyltrimethylammonium bromide (CTAB) have been studied in aqueous polyethylene glycol (PEG) mixed solvent systems of varying concentrations and molar mass. Interfacial behavior of CTAB was investigated by the equilibrium surface tension method. Conductance studies of surfactant solutions under different condition helped in determining the critical micelle concentration (CMC) and degree of dissociation of CTAB micelles. In addition, the limiting molar conductivity of surfactant and micellar species were evaluated from the differential plots. The CMC of CTAB was found to increase with increasing PEG concentration as well as its molar mass, although, the process of interfacial adsorption and micellization was found to be spontaneous, as evidenced by negative free energy change. The viscosity of CTAB micelles in aqueous‐PEG mixtures was found to increase with the increase in PEG concentration and molar mass. Dynamic light scattering measurements revealed a size enhancement effect contributed by the PEG oligomers. An increase in the CMC of CTAB and the subsequent presence of a higher number of ionic species in their dissociated form was further established by an overall increase in the zeta potential value in the presence of PEG oligomers. It is proposed that the PEG could wrap around the micelles through their conformational changes. Results also suggest that PEG oligomers could give solvophobic effect which enhances the CMC of CTAB compared to that in pure water.