Influence of growth conditions on the electrochemical synthesis of SnS thin films and their optical properties

Tin sulfide (SnS) thin films were prepared by electrodeposition onto fluorine-doped tin oxide (FTO) glass substrates using an aqueous solution containing SnCl₂ and Na₂S₂O₃ at various deposition potentials (E) and bath concentrations. The pH value and temperature of the solution were kept constant. The deposited films were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), photoluminescence (PL), and ultraviolet–visible (UV–Vis) spectroscopy. The FESEM images demonstrated that changes in the deposition potential (E) and solution concentration led to marked changes in the morphology of the deposited SnS films. Energy-dispersive X-ray analysis (EDXA) results showed that the Sn/S atomic ratio strongly depended on both the solution concentration and the deposition potential. To obtain an Sn/S atomic ratio approximately equal to 1, the optimal Sn2+/S₂O₃2- molar ratio and E parameter were 1/8 and -1.0 V, respectively. The XRD patterns showed that the synthesized SnS was obviously polycrystalline, with an orthorhombic structure. The effects of the variations of bath concentration and deposition potential on the band-gap energy (E_g) were studied using PL and UV–Vis experiments. The PL spectra of all the SnS films contained two peaks in the visible region and one peak in the infrared (IR) region. The UV–Vis spectra showed that the optical band-gap energy varies from 1.21 to 1.44 eV.     

Electrical and band-gap properties of amorphous zinc–ind ium–tin oxide thin films

Zinc–indium–tin oxide (ZITO) films were grown by pulsed-laser deposition. Three different material compositions were investigated: ZITO-30, ZITO-50 and ZITO-70 in which 30%,50% and 70%, respectively, of the indium in the In2O3 structure was replaced by substitution with zinc and tin in equal molar proportions (co-substitution): In22xZnxSnxO3, where x=0.3, 0.5, 0.7. All ZITO films grown at room temperature were amorphous. The first evidence of crystallinity was observed at higher deposition-temperature as the degree of co-substitution was increased. A decrease in mobility and conductivity was also observed as the degree of co-substitution was increased. The highest mobility for ZITO-30 and ZITO-50 was observed at deposition temperatures just prior to crystallization. The effect of deposition temperature on carrier concentration was minor compared to the effect of oxygen partial pressure during deposition.     

UV/visible spectroscopic analysis of CO<Superscript>3+</Superscript> and CO<Superscript>2+</Superscript> during the dissolution of cobalt from mixed Co-Cu oxidized ores

The leaching of cobalt from four-mixed Co-Cu oxidized ores containing cobalt at levels ranging from 0.5wt% to 34wt% was studied and the results has been reported. Conventional dissolution of these oxidized Co-Cu ores with diluted H₂SO₄ and SO₂ as a reducing agent resulted in a substantial improvement in the solution based recovery of cobalt. UV/visible spectroscopic analysis of the leached solutions indicated that the increased cobalt content in the solution was a result of flushing the acidified cobalt leaching solution with SO₂. Furthermore, UV/visible spectroscopy confirmed that as SO₂ was flushed into the acidified leaching solution, Co³⁺ bearing minerals were reduced to the readily soluble Co²⁺ bearing minerals, and this resulted in the increase of total cobalt in the collected solution. The mechanism of the reduction of Co³⁺ to Co²⁺ bearing minerals when SO₂ is flushed during the leaching of mixed Co-Cu oxidized ores, including the stability trends of Co³⁺, Co²⁺, and Cu²⁺ complexes, as shown by their UV/visible spectra, are also discussed.     

Mechanochemical preparation of sulfur-doped nanosized TiO2 and its photocatalytic activity under visible light

In order to make nanosized TiO2 photocatalyst responsive to visible light and effectively utilize solar energy, we have, for the first time, prepared S-doped nanosized TiO2 by a mechanochemical method with hydrolysis of TiCl4. The as-prepared S-doped nanosized TiO2 possesses strong absorption for visible light of 400-650 nm and shows high photocatalytic activity for decomposition of methylene blue under irradiation of visible light. The oxidation states of the S atoms incorporated into TiO2 were determined to be S^6＋ and S^4＋. The comparative study of fluorescence emission spectra shows that S-doping has also improved the separation of electron-hole pairs.     

Application of upconversion luminescence in dye-sensitized solar cells

An upconversion luminescence powder TiO2:(Er3+,Yb3+) is prepared by a hydrothermal method and used to fabricate dye-sensitized solar cell (DSSC).The TiO2:(Er3+,Yb3+) powder undergoes upconversion luminescence,converting infrared light which the dye can not absorb into visible light with wavelengths of 510-700 nm which the dye can absorb,increasing the photocurrent of the DSSC.TiO2:(Er3+,Yb3+) also acts as a p-type dopant,heightening the Fermi level of the oxide film,which increases the photovoltage of the DSSC.The best performance of the DSSC is found when the ratio of TiO2/luminescence powder is 1/3 in the luminescence layer.Under simulated solar irradiation of 100 mW cm-2 (AM 1.5),the DSSC containing TiO2:(Er3+,Yb3+) doping achieves a light-to-electricity energy conversion efficiency of 7.28% compared with 6.41% for the undoped DSSC.     

Mechanism of oxidative damage to DNA by Fe-loaded MCM-41 irradiated with visible light

The mechanism of oxidative damage to deoxyribonucleic acid (DNA) by iron-containing mesoporous molecular sieves (MCM-41) irradiated with visible light was elucidated. Fe-loaded MCM-41 (Fe/MCM-41) was used as a photocatalyst and the damage to calf thymus DNA caused by hydrogen peroxide (H2O2) was studied. The damage and extent of oxidation of DNA were measured by high-performance liquid chromatography (HPLC) and intermediate products were detected by HPLC/electrospray ionization tandem mass spectrometry. Electron spin resonance was used to detect changes in reactive oxygen species and peroxidase catalytic spectrophotometry was used to determine the concentration of H2O2. The results indicated that Fe/MCM-41 efficiently activated H2O2 in solution at pH 4.0-8.0 under irradiation with visible light. The photocatalytic system degraded DNA most effectively at pH 5.0-6.0 but also operated at pH 8.0. At pH 4.2, the degree of DNA damage reached 25.65% after 5 h and the kinetic constant was 5.89×10 2 min 1. Damage to DNA was predominantly caused by hydroxyl radicals generated in the system. The mechanism of DNA damage is of potential concern to human health because it can occur in neutral solutions irradiated by visible light.     

I-doping of anodized TiO<Subscript>2</Subscript> nanotubes using an electrochemical method

In order to obtain TiO2 with high photocatalytic activity, a cathode reduction was used to dope I⁷⁺ and I⁵⁺ into TiO₂ nanotubes of anodized Ti in C₂H₂O₄•2H₂O + NH₄F electrolyte. SEM images show that the anodization method integrated the preparation with the doping process, which for nonmetals-doping is advantageous to maintain the morphological integrity of TiO₂ nanotubes. I⁷⁺-I⁵⁺-doping enhances the UV response of TiO₂ and result in a red-shift. Under UV/visible irradiation, a I⁷⁺-I⁵⁺-doped sample (400°C) showed the highest I_ph and photocatalytic efficiency. A part of I^– in the I⁷⁺-I⁵⁺-doped sample is involved in the UV response, the red-shift and the higher I_ph.     

Internal energy transfer phenomenon and light-emission properties of γ-LiAlO2 phosphor doped with Mn2+

γ-LiAlO₂:Mn²⁺ phosphor was synthesized using the cellulose-citric acid sol-gel method, and its light emission and energy transfer properties were investigated. Excitation and emission spectrum analysis revealed a decrease in intensity of the spectrum as the amount of Mn²⁺ doping increased. Blasse’s equation determined the maximum distance for energy transfer between Mn²⁺ ions as 4.3142 nm. Dexter’s theory verifies that the mechanism of energy transfer between Mn²⁺ ions conforms to an electric dipole and electric quadrupole interaction.     

Soft chemical synthesis and luminescence properties of red long-lasting phosphors Y2O2S:Sm3+

Sm³⁺-activated Y₂O₂S red phosphors were prepared by the combustion method and microemulsion method at the first time. X-ray characterization and electron diffraction show that, Y₂O₂S:Sm³⁺, Ti⁴⁺, Mg²⁺ samples prepared by these two methods are pure hexagonal crystals in structure with a trivial change due to dopants. Scanning electron microscopy (SEM) results show that the product presents an almond-like sheet in uniform size. Under the excitation of 269 nm ultraviolet light, Y₂O₂S:Sm³⁺ samples fabricated by these two methods exhibit three main groups of red emission lines located at 564, 604, and 656 nm, respectively, which are attributed to the transitions of 4G_5/2 →6H_5/2, 4G_5/2 →6H_7/2, 4G_5/2 →6H_9/2, respectively. The samples prepared by microemulsion are seven times higher in fluorescent emission intensity and half time longer in afterglow time than that prepared by combustion.     

DC-bias and visible light effect on dielectric characteristics of La_(0.5)Cr_(0.5)TiO_(3+δ)

La_(0.5)Cr_(0.5)TiO_(3+δ) ceramic sample was prepared via traditional solid-state reaction route. Frequency and temperature dependence of dielectric permittivity were studied in the range of 10~2~ 10~6 Hz and of 77 ~360 K, respectively. It was observed that extraordinarily high low-frequency dielectric constants appeared at room temperature, and dielectric relaxation peaks shifted to higher temperature with increasing frequency. In the dc-bias studies, it was also found that the dielectric permittivity had obviously dc-bias dependence in low frequency, but independence as the frequency above 14 kHz. Interestingly, the dielectric characteristics of the sample had obvious light dependence at room temperature within the measured frequency range. The results demonstrate that visible light improves the dielectric properties of the ceramic by means of I–V and complex impedance analysis.     

Theoretical study of partial oxidation of ethylene by vanadium trioxide cluster cation

Density functional theory （DFT） study of reaction between vanadium trioxide cluster cation （VO3^＋） and ethylene （C2H4） to yield VO2^＋ ＋ CH3CHO （acetaldehyde） and VO2CH2^＋ ＋ HCHO （formaldehyde） is carried out. Structures of all reactants, products, intermediates, and transition state in the reaction have been optimized and characterized. The results show unexpected barriers in the reaction due to the existence of a η^2-O2 moiety in the ground state structure of VO3^＋. The initial reaction steps combining ethylene adsorption, C=C activation and O-O cleavage are proposed as rate limiting processes. Comparison of reactions of VO3^＋ ＋ C2H4 with VO3 ＋ C2H4 and VO2^＋ ＋ C2H4 in the previous studies is made in detail. The results of this work may shed light on the understanding of C=C bond cleavage in related heterogeneous catalysis.     

基于Pt-Au-MoS2-ITO传感器对于H2O2的还原检测

实验探究了二硫化钼（MoS₂）作为一种新型材料与贵金属纳米粒子金（Au）、铂（Pt）的复合基底对于过氧化氢（H₂O₂）的还原性检测,采用氧化铟锡导电玻璃（ITO）作为电极,制备出了基于Pt-Au-MoS₂-ITO的生物传感器,为H₂O₂还原性检测的便携性操作打下了基础.实验采用电化学沉积的方法制备材料,同时使用循环伏安（CV）法、计时电流法等传统电化学手段表征了传感器电化学性能,采用场发射扫描电子显微镜（FE-SEM）来表征传感器表面形貌.建立了用于H₂O₂还原检测的、具有高检测限、高灵敏度和宽检测范围的传感器.     

Thermoelectric properties of quaternary Mg2Sn0.4Si0.6−xGex alloys

Quaternary alloys Mg₂Sn_0.4Si_0.6−xGe_x (x=0, 0.02, 0.05, 0.08 0.1, and 0.2) were prepared using induction melting followed by hot-pressing. Relative densities of the sintered samples were over 97% of the theoretical values. Multiple phases were detected in the samples. It was found that the Seebeck coefficient was sensitive to the content of Mg₂Ge and a maximum value of about 350 μ V.K⁻¹ was obtained. The introduction of Ge increases the electrical conductivity and the thermal conductivity simultaneously. The mechanism of this phenomenon was discussed. A maximum dimensionless figure of merit, ZT, of about 0.28 was obtained for Mg₂Sn_0.4Si_0.55Ge_0.05 at 550 K.     

Modification of TiO2 nanotubes arrays by CdS and their photoelectrocatalytic hydrogen generation properties

In order to realize hydrogen generation under visible light, novel CdS/TiO2 nanotubes arrays are developed by electrochemical anodizaUon of Ti in 0.15 mol/L NHTF ＋ 0.08 mol/L H2C2O4 electrolyte. The diameter of the nanotube is 80-100 nm and the length is approximately 550 nm. The CdS nano-particles are deposited on the TiO2 nanotubes arrays by chemical bath deposition （CBD） in the ammonia-thiourea system. A 300 W Xe lamp is used as the light source, CdS/TiO2 nanotube arrays are used as the photoanode with the application of 1.0 V bath voltage, and 0.1 mol/L Na2S ＋ 0.04 mol/L Na2SO3 solution is used as the electrolyte, then the rate of photoelectrocatalytic hydrogen generation is 245.4 μL/（h·cm^2）. This opens new perspectives for photoelectrocatalytic hydrogen generation by using CdS/TiO2 nanotubes arrays.     

Theoretical study on stereodynamics of H + NeH+ (v = 0, j = 0) → H2 + + Ne reaction

Stereodynamics of reaction H + NeH+(v = 0,j = 0) → H2+ + Ne is investigated by quasi-classical trajectory method using a new potential energy surface constructed by Lv et al.The distributions of P(r),P(r) and PDDCSs are calculated at four different collision energies.The rotational polarization of product H2+ presents different characters at different collision energies.The product rotational angular momentum vector j’ is not only aligned,but also oriented along the direction perpendicular to the scattering plane.With the increase of collision energy,the rotation of product molecule has a preference of changing from the "in-plane" mechanism to the "out-of-plane" mechanism.Although the title reaction is mainly dominated by the direct reaction mechanism,the indirect mechanism plays a role when the collision energies are low.     

Pu(H2O)53+和Pu(H2O)54+ 团簇的相对论密度泛函研究

用TPSSTPSS密度泛函方法, Pu离子和H₂O分子分别采用相对论有效原子实势(RECP)和6-31g基组, 研究了Pu(H₂O)₅³⁺和Pu(H₂O)₅⁴⁺ 团簇溶剂化和非溶剂化效应中的几何结构及紫外可见吸收光谱. 计算结果表明: 水溶剂环境对Pu(H₂O)₅³⁺及Pu(H₂O)₅⁴⁺ 团簇的几何结构影响都比较明显. NBO电荷分析表明水分子与钚离子之间没有直接的电荷转移. 所研究团簇的未配对电子都占据5f轨道. 在气相及水溶剂环境下, 所研究团簇的紫外可见吸收光谱存在较大差距. 主要的吸收峰大都源于f电子之间的跃迁.     

Microstructural evolutions of Cu(Ni)/AuSn/Ni joints during reflow

Interfacial reactions of the Ni/AuSn/Ni and Cu/AuSn/Ni joints are experimentally studied at 330℃for various reflow times.The microstructures and mechanical properties of the as-solidified solder joints are examined.The as-solidified solder matrix of Ni/AuSn/Ni presents a typical eutecticξ-(Au,Ni)_5Sn+δ-(Au,Ni)Sn lamellar microstructure after reflow at 330℃for 30 s.After reflow for 60 s,a thin and flat(Ni,Au)_3Sn_2 intermetallic compound(IMC) layer is formed,and some needle-like(Ni,Au)_3Sn_2 phases grow f...     

Experimental evidence for formation water promoting crude oil cracking to gas

Crude oil cracking to gas is the key to determining the exploration potential and strategy for deep hydrocarbon resources.Identifying the factors that affect the threshold and potential of crude oil cracking to gas as well as other possible influencing factors will provide the scientific basis for deep hydrocarbon exploration.A comparison of pyrolysis simulation experiments of crude oil,hydrous crude oil,and various water media under a constant temperature(350℃) and pressure(50 MPa) shows that water plays a large role in crude oil cracking to gas.(1) When water is added,the gas yields increase significantly,including those of alkane gases and non-hydrocarbon gases:the yield of alkane gases increases 1.8-3 times;the yields of H2 and CO2 also increase significantly.This means that water takes part in the process of crude oil cracking to gas,and supplies hydrogen.Therefore,the presence of water will dramatically enhance the potential of crude oil cracking to gas.(2) Mg2+ ions in the formation water promote the crude oil + water reaction to some extent and increase the total yield of alkane gases and the yields of both H2 and CO2 ;more interestingly,the i-C4/n-C4 and i-C5/n-C5 ratios increase significantly.This indicates that Mg2+ ions in formation water act as a catalyst,and a disproportionation reaction is involved in the crude oil + water reaction.This study helps us to understand the factors influencing crude oil cracked gas and to evaluate the hydrocarbon resources in deep sedimentary basins.     

Hydrothermal synthesis of ultrathin Bi2MO6 (M=W,Mo) nanoplates as new host substances for red-emitting europium ion

Ultrathin Bi2MO6 (M?W, Mo) nanoplates were synthesized by a simple hydrothermal method. SEM, EDS and XRD were used to investigate the morphologies and compositions of the samples from BiONO3 nanoplates along with some nanoparticles, to precursory Bi2WO6 nanoplates and Bi2MoO6 nanoparticles, and to final Bi2MO6 nanoplates. The possible formation mechanism of products was proposed. The experimental results exhibited that Bi2MO6 nanoplates had stronger light adsorption in ultraviolet–visible range. Bi2MO6 nanoplates were useful host for rare earth ions, Eu3twas successfully doped in Bi2MO6 nanoplates and an energy efficiently transferred from Bi3t to Eu3t, displaying intense red color under ultraviolet (UV) light excitation. The morphologies of products kept constant after doping. It is suggested that Bi2MO6:Eu nanoplates have promising application in fluorescent mark.     

金属离子对钢在没食子酸/硫酸介质中的腐蚀行为研究

 用失重法研究了4种金属离子(Na⁺,Zn²⁺,Cu²⁺,Fe³⁺)在0.5 mol/L H₂SO₄以及500 mg/L没食子酸+0.5 mol/L H₂SO₄介质中在20℃对冷轧钢腐蚀行为的影响.结果表明:Cu²⁺对钢的腐蚀起抑制作用;而其余3种金属离子(Na⁺,Zn²⁺,Fe³⁺)对钢的腐蚀起加速作用.在相同条件下,冷轧钢在0.5 mol/L H₂SO₄溶液中的腐蚀速率顺序为:Cu²⁺2++3+;而在500 mg/L没食子酸+0.5 mol/L H₂SO₄介质中,腐蚀速率顺序为:Cu²⁺2+3++.