Enhanced magnetoconductivity and electrical property of MWCNT-CdS nanocomposite embedded in polyaniline

PANI/MWCNT-CdS nanocomposites with different content of CdS wt.% has been synthesized by the chemical oxidative in-situ polymerization reaction of aniline in the presence of multi-walled carbon nanotubes (MWCNT). TEM, XRD, FTIR, and TGA studies were done for the structural and thermal characterization of the samples respectively. The particle size of CdS nanoparticles distributes in between 2.7 and 4.8 nm. XRD spectrum reveals that the co-existence of MWCNT, CdS in PANI matrix, where CdS forms a hexagonal structure. TGA result shows that nanocomposite becomes more thermally stable with the increase in CdS content. The dc electrical transport property of PANI/MWCNT-CdS nanocomposites has been investigated within a temperature range 77 ≤ T ≤ 300 K. The dc conductivity follows a 3D variable range hopping (VRH) model. A large magnetoconductivity change (19%) is observed for 2 wt% CdS content in PANI/MWCNT-CdS, which is explained by the wave function shrinkage model.     

Nickel sulphide-reduced graphene oxide composites as counter electrode for dye-sensitized solar cells: Influence of nickel chloride concentration

Nickel sulphide-reduced graphene oxide (NiS-rGO) composite films have been prepared via modified Hummers’s method assisted with spin coating technique. The NiS-rGO samples were then employed as counter electrode in a dye-sensitized solar cell (DSSC). The main aim of this work is to investigate the relationship between the concentrations of NiCl₂ with the properties of NiS-rGO and performance parameters of the device. The dominant rGO and minor NiS phase exist in the composite. The morphology of the composite is white strips rGO and NiS agglomerate particle. The element of C, O, Ni and S present in the composite. The highest η of 1.04% and J_sc of 7.39 mA cm⁻² were obtained from the device with 0.06 M NiCl₂ resulted from the longest carrier lifetime. The photovoltaic parameters results reveal that NiS-rGO composite has potential to become as a free platinum counter electrode of DSSC.     

Determination of H2S,COS, CS2 and SO2 by an aluminium nitride nanocluster: DFT studies

ABSTRACT

Density functional theory calculations were used to investigate the potential application of an AlN nanocluster in the detection of H₂S, COS, CS₂ and SO₂ gases. In overall, the order of strength of interaction of these gases with the nanocluster is as follows: SO₂ (E_ad?=??17.6?kcal/mol)?>?H₂S (E_ad?=??14.0?kcal/mol)?>?COS (E_ad?=??8.4?kcal/mol)?>?CS₂ (E_ad?=??4.5?kcal/mol). This indicates that by increasing the electric dipole moment, the adsorption energy becomes more negative. We found that the Al₁₂N₁₂ nanocluster may be a promising work function-type sensor for SO₂ gas among the studied gases. Also, it is an electronic sensor for both SO₂ and CS₂ gases but selectively acts between them because of their different effects on the electrical conductivity. It is neither work function-type nor electronic sensor for H₂S and COS gases. The AlN nanocluster benefits from a short recovery time about 7.7?s and 18.0?ms for desorption of SO₂ and CS₂ gases from its surface at room temperature, respectively. It is also concluded that this cluster can work at a humid environment.     

Electrochemical Detection of Artemisinin Using Cobalt Sulphide/Reduced Graphene Oxide Nanocomposite

Solvothermally synthesized cobalt sulphide/reduced graphene oxide (CoS/rGO) was used to fabricate an electrochemical sensor for detection of artemisinin. Microscopic techniques were used to characterize CoS/rGO nanocomposite. The electrochemical sensor was fabricated by modifying the surface of glassy carbon electrode with CoS/rGO nanocomposite. [Fe(CN)6]^3−/4− was used as a mediator to aid oxidation of artemisinin. Differential pulse voltammetric technique was used for the detection of artemisinin. A linear range of 30–100 μM was used. Experimentally, a detection limit of 0.5 μM was obtained. Therefore, the developed sensor can be used for quality control of artemisinin.     

三价羰基硫离子(OCS3+)二体解离过程模拟研究

基于Gaussian量子化学模拟软件采用不同基组(6-31G^**和TZVP)下的B3LYP方法对基态三价羰基硫离子(OCS³⁺)的势能曲线进行分析,得到了三价羰基硫离子可能的解离通道.当固定C—O键长为OCS分子的构型键长时(2.1a.u.),通过模拟基态OCS³⁺离子沿着C—S键断裂的势能曲线,发现沿着C—S键的势能曲线是一个具有小势垒的排斥态;相反,当固定C—S键长为OCS分子的构型键长时(2.9a.u.),基态OCS³⁺离子沿着C—O键的势能曲线是一个势垒较大的排斥态,根据弗兰克-康登原理可知,基态OCS³⁺离子倾向于以断裂C—S键的方式进行解离.通过搜索基态OCS³⁺离子过渡态、IRC路径分析进一步确定了基态OCS³⁺离子具体的解离通道：OCS³⁺→CO⁺+S²⁺.最后通过对反应物和产物的Mulliken电荷分布和键长的分析,得到与前面一致的结论.     

Design and fabrication of multi-layers infrared antireflection coating consisting of ZnS and Ge on ZnS substrate

We have designed, fabricated and characterized a multi-layers antireflection coating on multispectral ZnS substrate, suitable for the infrared range of 8–12 μm. The 4-layers coating (Ge/ZnS/Ge/ZnS) with optimized thicknesses was fabricated by PVD technique and studied by FTIR, nanoindentation and AFM. From FTIR spectroscopy it was found that, in the wavelength range of 8–12 μm, the average transmittance of the double-side coated sample increases by about 26% and its maximum reaches about 98%. To improve the mechanical hardness, a bilayer of Y₂O₃/carbon was deposited on the coating. Nanoindentation test shows that the coating enhances the mechanical properties. The final coating have successfully passed durability and environmental tests.     

金属硫化物在可充电电池中的研究进展

低成本、长寿命、高安全性、高性能且易于大规模生产的锂/钠离子电池已被证实为重要的二次储能设备。 电极材料对锂/钠电池性能与循环寿命影响极大,金属硫化物由于具有高比容量和低电势而极具潜力成为锂/钠离子电池负极材料。 在电化学循环过程中,由于金属硫化物容易产生穿梭效应和体积变化,从而电极材料结构被破坏,进一步导致电池容量衰退、稳定性降低。 本文总结了多种金属硫化物的微观结构调控策略,从三维空间构建到与其它材料的复合,增强了电极的导电性和减缓体积变化带来的负面影响,进而获得性能优异的金属硫化物负极材料。 通过对金属硫化物的结构与性能的讨论,对其研究前景进行了积极的展望。     

Effect of corona discharge on cadmium sulphide and lead sulphide films

This paper describes the effect of corona discharge on cadmium sulphide (CdS) and lead sulphide (PbS) films prepared using the chemical route. The property of films before and after exposure to corona has been described in detail. The electronic properties of the CdS and PbS films have been studied by current-voltage (I-V), capacitance-voltage (C-V) measurements. The structural properties and surface morphology were studied by using X-ray diffraction and scanning electron microscopy before and after exposing to Corona discharge. The films displayed the change in surface morphology after exposure to the corona discharge. It has been found that the films showed an increase in resistivity after exposure. This change in property has been attributed to modification in surface states. Time-dependent recovery indicated that room temperature annealing is sufficient to regain the normal resistivity of the films. The experiment was carried with the aim of studying the effect of the interaction of corona discharge on the semiconductor films and its subsequent effects.     

Physical properties of ZnS thin films prepared by chemical bath deposition

Zinc sulphide thin films are deposited on SnO₂/glass using the chemical bath deposition technique. X-ray diffraction and atomic force microscopy are used to characterize the structure of the films; the surface composition of the films is studied by Auger electrons spectroscopy, the work function and the photovoltage are investigated by the Kelvin method. Using these techniques, we specify the effect of pH solution and heat treatment in vacuum at 500 °C. The cubic structure corresponding to the (1 1 1) planes of β-ZnS is obtained for pH equal to 10. The work function (Φ_material − Φ_probe) for ZnS deposited at pH 10 is equal to −152 meV. Annealing at 500 °C increases Φ_m (by about 43 meV) and induces the formation of a negative surface barrier. In all cases, Auger spectra indicate that the surface composition of zinc sulphide thin films exhibits the presence of the constituent elements Zn and S as well as C and O as impurity elements.     

First-principles study of SnS electronic properties using LDA,PBE and HSE06 functionals

Recently, tin sulphide (SnS) has emerged as a promising alternative to conventional CIGS and CZTC for use in solar cells, possessing such properties as non-toxicity, low cost and production stability. SnS has a high theoretically predicted efficiency above 20%, but the experimentally achieved efficiency so far is as low as 4.36%. The reason for the low achieved efficiency is unclear. One of the powerful tools to get deeper insights about the nature of the problem is first-principles calculation approaches. That is why SnS has become an attractive subject for first-principles calculations recently. Previously calculated data, however, show a widespread of such fundamental value as the bandgap varying from 0.26 to 1.26 eV. In order to understand a reason for that, in this work, we concentrate on a systematic study of calculation parameters effects on the resulting electronic structure, with the particular attention paid to the influence of the exchange-correlation functional chosen for calculations. Several exchange-correlation functionals (LDA, PBE and HSE06) were considered. The systematic analysis has shown that the bandgap variation can result from a tensile/compressive hydrostatic pressure introduced by non-equilibrium lattice parameters used for the calculations. The study of the applicability of three functionals has shown that HSE06 gives the best match to both experimentally obtained bandgap and the XPS valence band spectra. LDA underestimates the bandgap but qualitatively reproduces experimentally measured valence DOS similar to that of HSE06 in contrast to PBE. PBE underestimates the bandgap and does not match to the measured XPS spectra.