Fabrication of TiO2 nanoparticles/nanorod composite arrays via a two-step method for efficient dye-sensitized solar cells

Ti O2nanoparticles/nanorod composite arrays were prepared on the F-doped tin oxide(FTO)substrate through a two-step method of hydrothermal and d.c.magnetron sputtering.The microstructure and optical properties of the samples were characterized respectively by means of X-ray diffraction(XRD),field-emission scanning electron microscopy(FESEM)and UV–vis spectrometer.The results showed that the Ti O2composite nanorod arrays possess the nature of high surface area for more dye molecule absorption and the strong light scattering effects.The dye sensitized solar cells(DSSCs)based on Ti O2composite nanorod arrays exhibited a 80%improvement in the overall energy conversion efficiency compared with the pure Ti O2nanorod arrays photoanode.     

Preparation of Rectorite-TiO2 and Its Application in the Solar Photocatalytic Degradation of Dye Wastewater

A photocatalyst consisting of TiO2 powder and rectorite was prepared and activated utilizing solar light and used for degradation of simulated dye wastewater （methyl solution）. The effects of roasting temperature, the way of adding rectorite, and the amount of the rectorite on the photocatalytic activity have been investigated. The results indicated that rectorite-TiO2 photocatalyst prepared with the right proportional amount of rectorite and titanium dioxide, could effectively degrade the methyl orange solution in sunlight. After reacting in sunlight for 8 hours, the methyl orange decolorization reached 96%. The photocatalytic activity of rectorite-TiO2 was much better than that of TiO2 in sunlight.     

Fabrication and characterization of TiO2 -based dye-sensitized solar cells

Dye-sensitized solar cells TiO_2 with were fabricated.The phase composition and microstructures of the solar cells were examined by X-ray diffractometry and transmission electron microscopy,and the energy levels of the present solar cells were also discussed.The results show that a solar cell mixed with xylenol orange and rose Bengal shows a higher conversion efficiency compared to solar cells with a single dye.An introduction of amorphous TiO_2 layers results in an improvement of the conversion efficien...     

Synthesis of PbS–K2La2Ti3O10 composite and its photocatalytic activity for hydrogen production

Photocatalyst, lead sulfide (PbS )-intercalated layer perovskite-type compound (K2La2Ti3O10), was synthesized via ion-exchange reaction, butylamine pillaring and sulfuration processes under the assistance of the microwave irradiation. The structure of the photoc atalysts was determined by means of powder X-ray diffraction, scanning electron microscope, ultraviolet- visible diffuse reflection spectra and photoluminescence measu rement. And the photocatalytic activity of the composite compound for hydrogen production was also investigated. The experimental results showed that the intercalation of PbS in the layered space of K2La2Ti3O10 greatly improved the absorption edge and the photocatalytic activity. Hydrogen production of the PbS–K2La2Ti3O10 was 127.19 mmol/(g cat) after 3 h irradiation of ultraviolet light.     

Visible-light photocatalytic activity and mechanism of novel AgBr/BiOBr prepared by deposition-precipitation

A new composite photocatalyst AgBr/BiOBr was prepared by loading AgBr on a BiOBr substrate via deposition-precipitation and characterized by X-ray diffraction,scanning electron microscopy,high-resolution transmission electron microscopy and UV-vis diffuse reflectance spectroscopy.The as-prepared AgBr/BiOBr comprised face-centered cubic AgBr and tetragonal BiOBr particles.The average crystalline sizes of AgBr in the AgBr/BiOBr composites were less than 28.5 nm.The absorption edges of AgBr/BiOBr in visible-light region had a red shift with increasing AgBr content.Photocatalytic degradation of methyl orange results show that the AgBr/BiOBr composites could degrade methyl orange efficiently under visible-light irradiation (λ>420 nm).The optimal molar percentage of AgBr was 50 mol% with corresponding maximum k app of 0.00619 min -1.Active ·O 2- played a major role for methyl orange degradation while h + and ·OH had little effect on the photocatalytic process.The enhancement of photocatalytic activity of AgBr/BiOBr is mainly ascribed to the heterojunction effect between AgBr and BiOBr.     

Flexible dye-sensitized solar cell based on PCBM/P3HT heterojunction

Using blend heterojunction consisting of C60 derivatives [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and poly(3-hexylthiophene) (P3HT) as charge carrier transferring medium to replace I3–/I– redox electrolyte,a novel flexible dye-sensitized solar cell (DSSC) is fabricated.The characterization of infrared spectra and ultraviolet-visible spectra shows that the PCBM/P3HT heterojunction has not only the absorption in ultraviolet light for PCBM,but also the absorption in visible and near infrared light for P3HT,which widens the photoelectric response range for DSSC.The influence of PCBM/P3HT mass ratio on the performance of the solar cell is discussed.Under 100 mW cm–2 (AM 1.5) simulated solar irradiation,the flexible solar cell achieves a lightto-electric energy conversion efficiency of 1.43%,open circuit voltage of 0.87 V,short circuit current density of 3.0 mA cm–2 and fill factor of 0.54.     

Preparation and characterization of monodisperse spherical particles of X-ray nano-phosphors based on Gd2O2S:Tb

Monodisperse spherical Gd2O2S：Tb nanoparticles have been prepared using an improved homogeneous precipitation method combined with solid-gas sulfuration technology. The effects of Tb3＋-doped concentration on luminescent intensity and color purity of samples were investigated, and the optimal Tb3＋-doped concentration was determined. Under the excitation of X-ray, the obtained sample shows excellent luminescent properties, and its luminescent intensity is increased by about 50% under lower sulfuration temperature compared with that of the Gd2O2S：Tb nanoparticles prepared by complex precipitation method.     

Mg和La对Ca–Ti 处理钢中夹杂物演变和组织的影响

The evolution of inclusions and the formation of acicular ferrite (AF) in Ca–Ti treated steel was systematically investigated after Mg and La addition. The inclusions in the molten steel were Ca–Al–O, Ca–Al–Mg–O, and La–Mg–Ca–Al–O after Ca, Mg, and La addition, respectively. The type of oxide inclusion in the final quenched samples was the same as that in the molten steel. However, unlike those in molten steel, the inclusions were Ca–Al–Ti–O + MnS, Ca–Mg–Al–Ti–O + MnS, and La–Ca–Mg–Al–Ti–O + MnS in Mg-free, Mg-containing, and La-containing samples, respectively. The inclusions distributed dispersedly in the La-containing sample. In addition, the average size of the inclusions in the La-containing sample was the smallest, while the number density of inclusions was the highest. The size of effective inclusions (nucleus of AF formation) was mainly in the range of 1–3 μm. In addition, the content of ferrite side plates (FSP) decreased, while the percentage of AF increased by 16.2% due to the increase in the number of effective inclusions in the La-containing sample in this study.     

Effect of Gd2O3 on the microstructure and thermal properties of nanostructured thermal barrier coatings fabricated by air plasma spraying

The nanostructured 4–8 mol% Gd_2O_3-4.5 mol% Y_2O_3-ZrO_2(4–8 mol% Gd YSZ) coatings were developed by the atmospheric plasma spraying technique. The microstructure and thermal properties of plasmasprayed 4–8 mol% Gd YSZ coatings were investigated. The experimental results indicate that typical microstructure of the as-sprayed coatings were consisted of melted zones, nano-zones, splats, nano-pores,high-volume spheroidal pores and micro-cracks. The porosity of the 4, 6 and 8 mol% Gd YSZ coatings was about 9.3%, 11.7% and 13.3%, respectively. It was observed that the addition of gadolinia to the nano-YSZ could significantly reduce the thermal conductivity of nano-YSZ. The thermal conductivity of Gd YSZ decreased with increasing Gd_2O_3 addition. And the reduction in thermal conductivity is mainly attributed to the addition of Gd_2O_3, which results in the increase in oxygen vacancies, lattice distortion and porosity.     

Enhanced conversion efficiency of Yb2＋-Yb3＋-codoped glass as spectral converter for photovoltaic application

We propose a kind of Yb2＋-Yb3＋-codoped glass, which is used as spectral converter layer to adjust AM1.5 solar spectrum for a better match with silicon bandgap. The energy-level rate equations and power transmission equations are established to analyze the down-conversional effect of the codoped glass on solar spectrum. The numerical results show that with proper doping concentration and thickness the glass layer may improve conversion efficiency by about 12 %. Moreover, we also apply the modified spectrum as excitation source of solar cell in a simulation platform, and reveal that there is about 15 % improvement in practical cells.     

Antilocalization sensing of interactions between two-dimensional electrons and surface species

We apply antilocalization measurements to experimentally study the interactions and exchange between InAs surface accumulation electrons and local magnetic moments of the rare earth ions Sm3?,Gd3?,Ho3?,and Dy3?,of the transition metal ions Ni2?,Co2?,and Fe3?,and of Fe3O4nanoparticles and Fe3?-phthalocyanine deposited on the surface.The influence of the deposited species on the surface electrons is observed through the changes in the spin–orbit scattering and magnetic spin-flip scattering rates,which carry information about magnetic interactions.Experiments indicate a temperature-dependent magnetic spin-flip scattering for Ho3?,Dy3?,Ni2?,and Co2?.Concerning the spin–orbit scattering rate,we observe an increase,except for the cases of Ni2?,Fe3?,Fe3O4nanoparticles and Fe3?-phthalocyanine.We also observe an increase in SO scattering in another system where we study the interactions of Au nanoparticles and ferromagnetic Co0.6Fe0.4nanopillars and an In0.53Ga0.47As quantum well.Experimental results are analyzed and compared to theoretical models.Our method provides a controlled way to probe the quantum properties of two-dimensional electron systems,either on the surface of InAs or in a quantum well.     

Effect of annealing on properties of Mg doped Zn-ferrite nanoparticles

A comparison of structural and magnetic properties of as-prepared and annealed(900 1C) Mg doped Zn ferrite nanoparticles(Zn1 xMgxFe2O4,with x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) is presented. X-ray diffraction(XRD) studies confirmed the cubic spinel structure for both the as-prepared and annealed nanoparticles. The average crystallite size and lattice parameter were increased by annealing. Scanning electron microscopy(SEM)images also showed that the average particle size increased after annealing. Fourier transform infrared spectroscopy(FTIR) also confirmed the spinel structure for both series of nanoparticles. For both annealed and as-prepared nanoparticles, the O–Mtet.–O vibrational band shifts towards higher wave numbers with increased Mg concentration due to cationic rearrangement on the lattice sites. Magnetization studies revealed an anomalous decreasing magnetization for the annealed nanoparticles which is also ascribed to cationic rearrangement on the lattice sites after annealing. The measurement of coercivity showed a decreasing trend by annealing due to the increased nanoparticle size and better crystallinity.     

Characterization of γ-Fe2O3 nanoparticles prepared by transfor- mation of α-FeOOH

γ-Fe2O3 nanoparticles were successfully synthesized by a chemically induced transformation of α-FeOOH.In this method,the precursor(α-FeOOH)was prepared by chemical precipitation,and then treated with a mixed FeCl2/NaOH solution to produce the nanoparticles.X-ray diffraction indicated that when the precursor was treated with FeCl2(0.22 mol/L)and NaOH(0.19 mol/L),pure γ-Fe2O3 nanoparticles were obtained.However,when the concentration of FeCl2 was<0.22 mol/L or the concentration of NaOH was<0.19 mol/L,α-FeOOH and γ-Fe2O3 phases co-existed in the nanoparticles.Transmission electron microscopy observations showed that in the samples with co-existing phases,the nanoparticles did not have identical morphologies.The pure γ-Fe2O3 nanoparticles were polygonal rather than spherical.The volume ratio of α-FeOOH and γ-Fe2O3 was estimated for the two-phase samples from magnetization data obtained from a vibrating sample magnetometer.This chemically induced transformation is novel,and could provide an effective route for the synthesis of other metal oxide nanocrystallites.     

Characterization of MCrAlY/nano-Al_2O_3 nanocomposite powder produced by high-energy mechanical milling as feedstock for high-velocity oxygen fuel spraying deposition

Al_2O_3 nanoparticles and MCrAlY/nano-Al_2O_3 nanocomposite powder(M=Ni,Co,or NiCo) were produced using high-energy ball milling. The MCrAlY/nano-Al_2O_3 coating was deposited by selecting an optimum nanocomposite powder as feedstock for high-velocity oxygen fuel thermal spraying. The morphological and microstructural examinations of the Al_2O_3 nanoparticles and the commercial MCrAlY and MCrAlY/nano-Al_2O_3 nanocomposite powders were investigated using X-ray diffraction analysis, field-emission scanning electron microscopy coupled with electron dispersed spectroscopy, and transmission electron microscopy. The structural investigations and Williamson–Hall results demonstrated that the ball-milled Al_2O_3 powder after 48 h has the smallest crystallite size and the highest amount of lattice strain among the as-received and ball-milled Al_2O_3 owing to its optimal nanocrystalline structure. In the case of developing MCrAlY/nano-Al_2O_3 nanocomposite powder, the particle size of the nanocomposite powders decreased with increasing mechanical-milling duration of the powder mixture.     

Effect of Yb2O3 doping on the grain boundary of NiFe2O4–10NiO-based cermets after sintering

xYb2O3–15(20Ni–Cu)/(85?x)(NiFe2O4–10NiO) (x=0, 0.25, 0.5, 0.75, 1.0, 2.0, and 10.0) cermets for aluminum electrolysis were prepared to investigate the effect of Yb2O3 doping on the grain boundary of the cermets after sintering. The results showed that each interface was very clear and that with increasing Yb2O3 content, most of the Yb was evenly distributed at the grain boundary. Moreover, according to the phase composition and microstructural analysis by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), and electron probe microanalysis (EPMA), YbFeO3 was produced along the grain boundary. The YbFeO3 was concluded to not only have formed from the interaction between the NiFe2O4 or Fe2O3 component and Yb2O3 at the grain boundary of the cermets, but also from the decomposition of NiFe2O4 into NiO and Fe2O3 and the subsequent reaction of Fe2O3 with Yb2O3. Thus, the pro-duction of YbFeO3 resulted in a cermet with high relative density, good electrical conductivity, and good corrosion resistance.     

Characterization of NbSi_2–Al_2O_3 nanocomposite coatings prepared with plasma spraying mechanically alloyed powders

The present study characterized NbS i2–Al2O3 nanocomposite powders plasma-sprayed on Ti–6Al–4Vsubstrates. The powders were agglomerated to obtain suitable particle sizes for spraying. The agglomerated powders were then plasma-sprayed using atmospheric plasma spraying. The structural transformations of the powders along with the morphological and mechanical changes of the coatings were examined by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, and hardness testing. The results showed that after plasma spraying, the grain size increased, and the lattice strain decreased. However, the grain size of this compound after spraying was still in the nanometer range. The coating was uniform and exhibited good adhesion to the substrate. The microhardness and fracture toughness of the nanocomposite coating were higher than those of a nanostructured NbS i2 coating.     

Synthesis,characterization,and theoretical study of N,S-codoped nano-TiO2 with photocatalytic activities

Nitrogen and sulfur doped titanium dioxide photocatalysts were prepared by the sol-gel method.The products were characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM),and UV-visible diffuse reflectance spectra (DRS).Photocatalytic activities of the samples were investigated on the degradation of methyl orange (MO).The effect of the dopants on the electronic structure of TiO2 was studied by the first-principles calculations based on the density functional theory (DFT).The orbital hybridization resulted in energy gap narrowing and electronic delocalization in the crystal of doped TiO2.Mobile electrons of varied energetic states could offer enhanced electron transfer,together with optical absorption improvement.The results show that the doping elements of N and S play a cooperative role in the modification of electronic structure,which enhances the photocatalytic performance.The experimentally observed absorption edges of N-doped TiO2,S-doped TiO2,and N,S-codoped TiO2 are 420,413,and 429 nm,respectively,which can be explained by the theoretical calculation results.     

Microstructure and properties of Cu–Ti–Ni alloys

The effects of Ni addition and aging treatments on the microstructure and properties of a Cu–3Ti alloy were investigated. The microstructure and precipitation phases were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy; the hardness, electrical conductivity, and elastic modulus of the resulting alloys were also tested. The results show that Ni addition increases the electrical conductivity and elastic modulus, but decreases the hardness of the aged Cu–3Ti alloy. Within the range of the experimentally investigated parameters, the optimal two-stage aging treatment for the Cu–3Ti–1Ni and Cu–3Ti–5Ni alloy was 300°C for 2 h and 450°C for 7 h. The hardness, electrical conductivity, and elastic modulus of the Cu–3Ti–1Ni alloy were HV 205, 18.2% IACS, and 146 GPa, respectively, whereas the hardness, electrical conductivity, and elastic modulus of the Cu–3Ti–5Ni alloy were HV 187, 31.32% IACS, and 147 GPa, respectively. Microstructural analyses revealed that β′-Ni3 Ti and β′-Cu4 Ti precipitate from the Cu matrix during aging of the Cu–3Ti–5Ni alloy and that some residual Ni Ti phase remains. The increased electrical conductivity is ascribed to the formation of Ni Ti, β′-Ni3 Ti, and β′-Cu4 Ti phases.     

Effect of Yb_2O_3 doping on the grain boundary of NiFe_2O_4–10NiO-based cermets after sintering

xY b2O3–15(20Ni–Cu)/(85- x)(NiF e2O4–10NiO)(x = 0, 0.25, 0.5, 0.75, 1.0, 2.0, and 10.0) cermets for aluminum electrolysis were prepared to investigate the effect of Yb2O3 doping on the grain boundary of the cermets after sintering. The results showed that each interface was very clear and that with increasing Yb2O3 content, most of the Yb was evenly distributed at the grain boundary. Moreover, according to the phase composition and microstructural analysis by X-ray diffraction(XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy(SEM/EDX), and electron probe microanalysis(EPMA), YbF eO 3 was produced along the grain boundary. The YbF eO 3 was concluded to not only have formed from the interaction between the NiF e2O4 or Fe2O3 component and Yb2O3 at the grain boundary of the cermets, but also from the decomposition of NiF e2O4 into NiO and Fe2O3 and the subsequent reaction of Fe2O3 with Yb2O3. Thus, the production of YbF eO 3 resulted in a cermet with high relative density, good electrical conductivity, and good corrosion resistance.     

Structural,morphological, Raman,optical, magnetic,and antibacterial characteristics of CeO<Subscript>2</Subscript> nanostructures

In this study, CeO₂ nanostructures were synthesized by a soft chemical method. A hydrothermal treatment was observed to lead to an interesting morphological transformation of the nanoparticles into homogeneous microspheres composed of nanosheets with an average thickness of 40 nm. Structural analysis revealed the formation of a single-phase cubic fluorite structure of CeO₂ for both samples. A Raman spectroscopic study confirmed the XRD results and furthermore indicated the presence of a large number of oxygen vacancies in the nanosheets. These oxygen vacancies led to room-temperature ferromagnetism (RTFM) of the CeO₂ nanosheets with enhanced magnetic characteristics. Amazingly, the nanosheets exhibited substantially greater antibacterial activity than the nanoparticles. This greater antibacterial activity was attributed to greater exposure of high-surface-energy polar surfaces and to the presence of oxygen vacancies.