Recent advances in quantum dot catalysts for hydrogen evolution:Synthesis,characterization,and photocatalytic application

Photocatalytic water splitting is beneficial for the effective mitigation of global energy and environmental crises.Owing to multi-exciton generation,impressive light harvesting,and excellent photochemical properties,the quantum dot(QD)-based catalysts reveal a considerable potential in photocatalytic hydrogen(H_(2))production compared with bulk competitors.In this review,we summarize the recent advances in QDs for photocatalytic H_(2) production by enumerating different synthetic and characterization strategies for QDs.Various QDs-based photocatalysts are introduced and summarized in categories,and the role of different QDs in varied systems,as well as the mechanism and key factors that enhance the photocatalytic H_(2) generation performance,is discussed.Finally,conclusions and future perspectives in the exploration of highly efficient QDs-based photocatalysts for innovative applications are highlighted.

Synthesis and characterization of ε-VOPO_4 nanosheets for secondary lithium-ion battery cathode

Vanadium （III） phosphate monoclinic VPO4·H2O was synthesized hydrothermally. The ε-VOPO4 nanosheets, formed by the oxidative de-intercalation of protons from monoclinic VPO4·H2O, can reversibly react with more than 1 mol lithium atoms in two steps. Crystal XRD analysis revealed that the structure of the ε-VOPO4 nanosheets is monoclinic with lattice parameters of α=7.2588（4） A, b=6.8633（2） A and c=7.2667（4） A. The results show that the ε-VOPO4 nanosheets have a thickness of 200 nm and uniform crystallinity. Electrochemical characterization of the ε-VOPO4 monoclinic nanosheets reveals that they have good electrochemical properties at high current density, and deliver high initial capacity of 230.3 mA· h/g at a current density of 0.09 mA/cm2. Following the first charge cycle, reversible electrochemical lithium extraction/insertion at current density of 0.6 mA/cm2 affords a capacity retention rate of 73.6% （2.0？4.3 V window） that is stable for at least 1000 cycles.

Synthesis and characterization of ZnTiO_3 with high photocatalytic activity

Perovskite ZnTiO3 was prepared through a new method which contained a hydrothermal process for the preparation of titanate nanotubes and an ion-exchange process.The titanate nanotubes were inferred to be H2Ti3O7·3H2O.X-ray diffraction（XRD）result revealed the presence of cubic perovskite phase of ZnTiO3.The unique chain-like morphology of ZnTiO3 was observed by scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.UV-Vis diffusive reflection spectra of ZnTiO3indicated that the absorbance obviously increased in the visible light region.The degradation rate of methyl orange solution（15 mg/L）reached 95.3%over ZnTiO3（0.3 g/L） after 20 min xenon light irradiation,which was higher than that using the commercial catalyst P25 under the same reaction condition.The degradation kinetic results follow the first-order equation and the rate constant is 0.1020.

Synthesis and Characterization of Microcapsules with Chlorpyrifos Cores and Polyurea Walls

Microcapsules with chlorpyrifos cores and polyurea walls were synthesized with 2,4-tolylene diisocyanate as an oil-soluble monomer and ethylenediamine as a water-soluble monomer via an interracial polycondensation reaction. The products were characterized by means of Fourier transform infrared spectrometry, ^13C NMR spectrometry and ^31p NMR spectrometry. The morphology, the particle size and the particle size distribution, and the thermal properties were also evaluated. The prepared microcapsules exhibit clear and smooth surfaces and have a mean diameter of 28. 13 μm. These microcapsules also have a good thermal stability for long-term use, and have potential applications in minimizing the toxicity of chlorpyrifos through controlled release.

Synthesis,characterization and catalytic properties of Y-β zeolite composites

Y-β zeolite composites were hydrotherrnally synthesized by using high silica Y zeolite as the precursor and characterized by XRD, N2 adsorption, SEM and IR spectra of pyridine. The result showed that the N2 adsorption-desorption isotherm of the zeolite composites had a distinct hysteresis loop, and the SEM result showed that the zeolite composites had a different morphology from Y, β and the corresponding physical zeolite mixture. The acid catalytic performance of the zeolite composite catalysts was investigated in the hydrocracking and hydroisomerization of n-octane, and the results showed that the composite materials exhibited an excellent hydrocracking activity and good hydroisomerization performance. The yield of i-C4 over the zeolite composite catalyst was 4.45% higher than that on the corresponding zeolite mixture in the n-octane hydrocracking process at 553 K. The isomerization ability of n-octane over the composite catalyst was 3.6 fold that of the corresponding mixture at 503 K.

Synthesis and Characterization of Dual Acidic Ionic Liquids

Novel ionic liquids with dual acidity, of which the cation contains Brφnsted acidity and anions contain Lewis acidity were synthesized. These ionic liquids obtained were identified by NMR, FF-IR, SDT and FAB-MS. Their acidities were determined by pyridine probe on IR spectrography.

Synthesis and Characterization of Y-Doped Mesoporous CeO_2 Using A Chemical Precipitation Method

Using cetyltrimethylammonium bromide （CTAB） as the template agent, cerium nitrate as the cerium resource, yttrium nitrate as the yttrium resource, and ammonium carbonate as the precipitating agent, mesoporous CeO2 powders doped with different yttrium contents were successfully synthesized using a chemical precipitation method, under an alkalescent condition. Properties of the obtained samples were characterized and analyzed with X-ray diffraction （XRD）, energy dispersive analysis of X-rays （EDAX）, transmission electron microscopy （TEM）, infrared （IR） absorbance, and the BET method. For the prepared samples with 20% （molar ratio） Y-doped content, a BET specific surface area of 106. 6 m^2 · g^- 1, with an average pore size of3~27 nm were obtained. XRD patterns showed that the doped samples were with a cubic fluorite structure. TEM micrographs revealed that the doped samples showed a spherical morphology with a diameter ranging from 20 to 30 nm and a round pore shape. IR results indicated that the Ce-O-Ce vibration intensity decreased as the Y-doped content increased. N2 adsorption-desorption isotherms showed that the samples possessed typical mesopore characteristics. The average pore size of the samples decreased alter mesoporous CeO2 was doped with yttrium, and the average pore size decreased largely as the Y-doped content increased.

Synthesis and Characterization of CdSe Nanocrystals Capped by CdS

CdSe semiconductor nanocrystals capped by CdS were synthesized in the aqueous solution with 2 mercaptoethanol as the stabilizer. The CdS capping with a higher band gap than that of the core crystallite has successfully eliminated the surface traps. Optical absorption and fluorescence emission spectra were used to probe the effect of CdS passivation on the electronic structure of the nanocrystals. The composite CdSe/CdS nanocrystals exhibit strong, narrow(FWHM≤40 nm) and stable band edge photoluminescence. X ray powder diffraction, transmission electron microscopy and X ray photoelectron spectroscopy were used to analyze the composite nanocrystals and determine their average size, size distribution, shape, internal structure and elemental composition.

Preliminary Synthesis and Characterization of Mesoporous Nanocrystalline Zirconia

A novel method to prepare mesoporous nano-zirconia was developed. Thesynthesis was carried out in the presence of PEO surfactants via a solid-state reaction. Thematerials exhibit a strong diffraction peak at low 2θ angle and their nitrogenadsorption/desorption isotherms are typical of type IV with H1 hysteresis loops. The pore structureimaged by TEM can be described as wormhole domains. The tetragonal zirconia nanocrystals are uniformin size (around 1.5 nm) and their mesopores focus on around 4.6 nm. The zirconia nanocrystal growthis tentatively postulated to be the result of an aggregation mechanism. This study also revealsthat the PEO surfactants can interact with the Zr-O-Zr framework to reinforce the thermal stabilityof zirconia. The ratio of NaOH to ZrOCl_2, crystallization and calcination temperature play animportant role in the synthesis of mesoporous nano-zirconia.

Synthesis, Characterization and Formation Mechanism of Friedel's Salt(FS:3CaO·A1_2O_3·CaCl_2·10H_2O) by the Reaction of Calcium Chloride with Sodium Aluminate

The synthesis of Friedel＇s salt （FS： 3CaO·Al2O3·CaCl2·10H2O） by the reaction of calcium chloride with sodium aluminate was investigated. Factors affecting the preparation of Friedel＇s salt, such as reaction temperature, initial concentration, titration speed, aging time and molar Ca/Al ratio were studied in detail. XRD, SEM images and particle size distribution show that the reaction temperature, aging time and molar Ca/Al ratio have significant effect on the composition, crystal morphology, and average particle size of the obtained samples. In addition, the initial CaCl2 concentration and NaAlO2 titration speed do not significantly influence the morphology and particle size distribution of Friedel＇s salt. With the optimization of the operating conditions, the crystals can grow up to a average size of about 28 μm, showing flat hexagonal （or pseudo- hexagonal） crystal morphology. Moreover, two potential mechanisms of Friedel＇s salt formation including adsorption mechanism and anion-exchange mechanism were discussed. In the adsorption mechanism, Friedel＇s salt forms due to the adsorption of the bulk C1- ions present in the solution into the interlayers of the principal layers, [Ca2Al（OH-）6·2H2O]＋, in order to balance the charge. In the anion-exchange mechanism, the freechloride ions bind with the AFro （a family of hydrated compounds found in cement） hydrates to form Friedel＇s salt by anion-exchange with the ions present in the interlayers of the principal layer, [Ca2Al（OH-）6. 2H2O]＋- OH-.

Synthesis, Characterization and Antioxidative Activity of Lanthanide Complexes with Genistein

Six genistein lanthanide complexes, LnL_2 (OAc)·nH_2O [Ln=La(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), (Tb(Ⅲ),) Dy(Ⅲ); L=genistein; n=4, 7, 8] were synthesized and characterized on the basis of elemental analyses, IR, (()~1H) NMR spectra and molar conductivity. The scavenging activity of genistein and five lanthanides complexes on the hydroxyl free radicals (OH·) was also investigated by spectrophotometric methods. The results show that the scavenging activity of the complexes is better than that of the ligand and their scavenging ability can be assembled in the following order: Sm>La>Dy>Eu>Tb>L.

Synthesis, Characterization and Thermal Decomposition Mechanism of Cetyltrimethyl Ammonium Tetrathiotungstate

The synthesis, characterization and thermal decomposition mechanism of cetyltrimethyl ammonium tetrathiotungstate （CTriMATT） were studied herein. The as-synthesized CTriMATT was characterized by Elemental analysis, X-ray diffraction （XRD）, Fourier transform infrared （FT-IR）, Ultraviolet visible （UV-Vis） spectra. The results showed that the as-synthesized CTriMATT had high purity and good crystallinity. The introduction of alkyl groups induced a shift of the stretching vibration band of W-S bond to lower wavenumber, while it had no influence on the position of WS4^2-. Thermogravimetric analysis （TG）, differential thermal analysis （DTA） and in situ XRD characterizations revealed that CTriMATT began to decompose at 423 K in nitrogen and was converted to WS2 eventually. In addition, the decomposition product of CTriMATT at 673 K in nitrogen was characterized by N2 adsorption （BET） and scanning electron microscopy （SEM）. The results demonstrated that WS2 with higher specific surface area, and pore volume could be obtained from the thermal decomposition of CTriMATT in nitrogen.

Synthesis and structure characterization of diethyldiallylammonium chloride

The unsaturated quaternary ammonium salt diethyldiallylammonium chloride(DEDAAC) was synthesized in a two-step synthetic method. The influences of the adding method of raw materials and temperature on the yields of diethylallylamine (DEAA), and drying and temperature on the synthesis of DEDAAC were investigated. The content of in-process product DEAA was determined by non-aqueous titration. The structure of product DEDAAC was identified with IR, 1 H NMR and elemental analysis. The results show that adding allyl chloride and sodium hydroxide alternately can increase the yield of DEAA and decrease by-products. In further synthesizing of DEDAAC from DEAA, the step of drying DEAA is very necessary. When DEAA is dried by solid sodium hydroxide, good columnar crystals with a high purity(mp 199.5-201.0 ℃) are obtained; when DEAA is undried or the content of water in DEAA is above 20%, only platelets with bad quality are obtained even without crystals. The suitable synthesis conditions for DEAA and DEDAAC are 35 ℃, 6 h and 40 ℃, 36 h, respectively, and their yields are 69.7% and 67.3%, respectively.

Synthesis and Characterization of Montmorillonite Inorgano-Intercalation Compound Assisted by Microwave Irradiation

A montmorillonite inorgano-intercalation compound（MIIC） was synthesized by using a purified Na-exchanged bentonite（PNaB） as a matrix and Al-pillaring ion as an intercalating reagent under microwave irradiation.The synthesized products were characterized by X-ray diffraction（XRD）,^27Al magic angle sample-spinning nuclear magnetic resonance（^27Al MAS NMR）,specific surface area（BET） measurement,and adsorption density determination.The results show that,at 5% solid（PNaB） concentration and 7 minutes irradiation in a 130 W microwave oven,the basal spacing d（001） of the synthesized MIIC increases to 1.740 nm from the original 1.218 nm of PNaB.The MIIC has much higher adsorptive densities to F-and Cr^6＋ from aqueous solution than the PNaB.The adsorption isotherm of F-on the MIIC follows the Freundlich equation,and the increased adsorption is mainly due to the porous structure of the MIIC which created larger adsorption surfaces.The adsorption isotherm of Cr^6＋ on MIIC follows the Langmuir equation and the adsorption is mainly monolayer as a result of chemisorptions.

Synthesis and characterization of conjugated polymer containing azobenzene and oxadiazole units

A novel conjugated polymer containing azobenzene and oxadiazole units was synthesized through multi-step synthesis. The structures and properties of monomer and polymer were characterized and evaluated with IR, ^1H NMR, UV, TGA and GPC, respectively. Polymer with long side chain of alkoxy shows good solubility, thermal stability and photoisomerization property.

Synthesis and Characterization of Quaternary Complexes Ln(CH_2ClCOO)_2 (NO_3) (phen)

Many binary lanthanide complexes have been studied. However, few mixed anion complexes with bidentate heterocyclic amines were synthesized. We synthesized mixed anion complexes Ln ( CH2 ClCOO )2 (NO3 ) ( phen) which was determined by elemental analyses . The IR spectra analyses indicate that NO3- , CH2 ClCOO- and phen are coordinated with Ln . The molar conductances of the complexes at 10-3 mol · L-1 were founded to be between 32.4 and 35.8 S·cm2· mol-1 , suggesting the nonelectrolytes in N-Dimethylformamide. And we determined the fluorescent spectra Eu(CH2ClCOO)2(NO3) ( phen ) and ESR spectra of Gd ( CH2 ClCOO )2 ( NO3) ( phen) .

Synthesis and Structural Characterization of 2,3-Bis(hydroxymethyl)-2,3-dinitro-1,4-butanediol

2,3-Bis（hydroxymethyl）-2,3-dinitro-1,4-butanediol（C6H12N2O8） was synthesized by condensation,cyclization,oxidative dimerization and deketalization of nitromethane with a total yield of 42.4%.The structure of the title compound was characterized by 1H NMR,13C NMR,FT-IR,elementary analysis,and X-ray single-crystal diffraction analysis,which reveals that the title compound crystallizes in triclinic,space group P with a = 0.6324（2）,b = 0.6454（3）,c = 0.7062（3） nm,α= 111.550（4）,β= 95.505（4）,γ= 113.395（4）°,V = 0.23595（16） nm3,Z = 1,Mr = 240.18,Dc = 1.690 g·cm-3,μ = 0.159 mm-1,F（000） = 126,R = 0.0304 and wR = 0.0907.

Individualized Pixel Synthesis and Characterization of Combinatorial Materials Chips

Conventionally, an experimentally determined phase diagram requires studies of phase formation at a range of temperatures for each composition, which takes years of effort from multiple research groups. Combinatorial materials chip technology, featuring high-throughput synthesis and characterization, is able to determine the phase diagram of an entire composition spread of a binary or ternary system at a single temperature on one materials library, which, though significantly increasing efficiency, still requires many libraries processed at a series of temperatures in order to complete a phase diagram. In this paper, we propose a "one-chip method" to construct a complete phase diagram by individually synthesizing each pixel step by step with a progressive pulse of energy to heat at different temperatures while monitoring the phase evolution on the pixel in situ in real time. Repeating this process pixel by pixel throughout the whole chip allows the entire binary or ternary phase diagram to be mapped on one chip in a single experiment. The feasibility of this methodology is demonstrated in a study of a Ge-Sb-Te ternary alloy system, on which the amorphouscrystalline phase boundary is determined.

Synthesis and Characterization of Some Lanthanide(Ⅲ) Complexes with 4-[N-(2-methoxybenzylimine)formyl]-2, 3-dimethyl-1-phenyl-3-pyazolin-5-one

A series of seven novel lanthanide（Ⅲ ） nitrato complexes with 4-[ N-（2-methoxybenzylimine）formyl] 1-2, 3- dimethyl-1-phenyl-3-pyazolin-5-one （2mbfa）, were synthesized. These complexes were characterized by elemental analysis, molecular mass determination, conductance and magnetic moment measurements, IR, UV-visible, and ^13CNMR spectral studies, In these complexes, the Schiff base, 2mbfa, acts as neutral bidentate ligand by utilizing the carbonyl oxygen and azomethine nitrogen as donor sites. All the three nitrate ions are also coordinated unidentately with 7 coordination for the lanthanide（Ⅲ） ions with a tentative monocapped octahedral geometry for the complexes. All the seven lanthanide（Ⅲ） complexes have a general formula, [ Ln（2mbfa）：（NO3）3 ].

Synthesis and Characterization of Novel N-Ferrocenesulfonyl Benzimidazole

A new series of ferrocenesulfonyl benzimidazle has been synthesized and characterized by 1H NMR, FT-IR and elemental analysis. They are expected to have special bio-activity.