Sn Anodes Protected by Intermetallic FeSn2 Layers for Long-lifespan Sodium-ion Batteries with High Initial Coulombic Efficiency of 93.8 %

With a theoretical capacity of 847 mAh g⁻¹, Sn has emerged as promising anode material for sodium-ion batteries (SIBs). However, enormous volume expansion and agglomeration of nano Sn lead to low Coulombic efficiency and poor cycling stability. Herein, an intermetallic FeSn₂ layer is designed via thermal reduction of polymer-Fe₂O₃ coated hollow SnO₂ spheres to construct a yolk-shell structured Sn/FeSn₂@C. The FeSn₂ layer can relieve internal stress, avoid the agglomeration of Sn to accelerate the Na⁺ transport, and enable fast electronic conduction, which endows quick electrochemical dynamics and long-term stability. As a result, the Sn/FeSn₂@C anode exhibits high initial Coulombic efficiency (ICE=93.8 %) and a high reversible capacity of 409 mAh g⁻¹ at 1 A g⁻¹ after 1500 cycles, corresponding to an 80 % capacity retention. In addition, NVP//Sn/FeSn₂@C sodium-ion full cell shows outstanding cycle stability (capacity retaining rate of 89.7 % after 200 cycles at 1 C).     

锂离子电池高比容量FeSn2-C复合负极材料的合成与性能

Sn基合金负极材料具有高达990 mAh·g^-1的理论比容量,但其也存在因脱嵌锂过程发生巨大的体积变化而导致循环性能较差的问题. 本文以Sn、Fe、石墨为原料利用简易的高能球磨法成功制备了具有核壳结构的FeSn₂-C复合物,系统研究了球磨时间、FeSn₂相含量对材料物相结构及电化学性能的影响,并分析了电极的失效机理. 研究表明,球磨时间的增加有利于FeSn₂金属间化合物相的形成及材料颗粒的细化,进而有利于材料比容量的增加及循环性能的提升;FeSn₂相含量的增加能够提高FeSn₂-C材料的比容量,但会降低FeSn₂-C电极的循环稳定性. 经工艺优化及组分调节,球磨24 h合成的Sn₂₀Fe₁₀C₇₀材料具有最优的电化学性能,材料的比容量在540 mAh·g^-1左右,并能稳定循环100次,是一种非常有发展前途的锂离子电池高比容量负极材料.     

Improved photovoltaic performance from high quality perovskite thin film grown with the assistance of PC<Subscript>71</Subscript>BM

The strategy of sequentially spin-coating a perovskite film from the perovskite precursor and an electron transporting layer of [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) is developed to simplify the fabrication procedure of perovskite solar cells. X-ray diffraction and scanning electron microscopy indicate that PC₇₁BM film on perovskite layer can retard the evaporation of dimethyl sulfoxide (DMSO) efficiently, thus prolonging the transformation of intermediate phase to perovskite crystals, leading to a high quality perovskite thin film. The solar cells with the structure of indium tin oxides (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/CH₃NH₃PbI₃/PC₇₁BM/bathocuproine (BCP)/Ag made from this simplified method exhibit a higher efficiency (12.68%) than those from the conventional one-step method (9.49%).     

Preparation of Tin Oxide-Based Metal Oxide Particles

Tin oxide-doped hybrid particles were prepared by a wet chemical process with organic-inorganic (phenyl/silica) hybrid particles in an alcoholic solution. The phenyl/silica hybrid particles, with a diameter of ca. 790 nm were used as a new support material for tin oxide (SnO₂) particles from tin(IV) chloride. The surface of the particles was modified via nitration of aromatic groups in the particles, to promote formation of the tin oxide coating on the particles. The thickness and surface morphology of the tin oxide layer coated on the nitrated-phenyl/silica hybrid particles could be controlled by varying the tin(IV) chloride concentration and reaction time. The size and morphology of the resultant particles were investigated with field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The particles obtained were also characterised by infrared (FTIR) and solid-state ¹³C magic angle spinning nuclear magnetic resonance (¹³C-CP/MAS NMR) spectroscopy. The effect of processing parameters on the crystallinity and structure of the doped hybrids were confirmed by X-ray diffraction (XRD) patterns.     

Use of X-Ray Absorption Spectra as a “Fingerprint” of the Local Environment in Complex Chalcogenides

The local environment of tin, titanium, iron, and sulfur in spinel compounds Cu₂FeSn₃S₈ and Cu₂FeTi₃S₈ was studied by X-ray absorption spectroscopy (XAS) at the titanium, iron, sulfur K edges, and the tin L_I-edge. As detailed calculations of the electronic structure of these compounds are difficult to carry out due to the large number of atoms contained in the unit cell, the XAS spectra of the spinels are compared to those of relatively simple binary sulfides like SnS₂, TiS₂, and FeS. Indeed, the metal environments in these binary compounds are very similar to those in the spinels, and they can be considered good model compounds allowing the interpretation of electronic transitions observed in the spectra of quaternary phases. In the latter, the bottom of the conduction band is mainly formed by Sn 5s–S 3p, Sn 5p–S 3p antibonding states for the tin-based compounds and by Ti 3d_t2g–S 3p, Ti 3d_eg–S 3p antibonding states for the titanium-based compounds. It it shown that the local environment of iron atoms remains unchanged when substituting tin with titanium atoms, according to a topotactic substitution.     

ZnO/In2O3复合空心球的制备及其光电催化葡萄糖降解性能

通过葡萄糖协助的水热以及随后的退火处理两步法成功制备了系列ZnO/In₂O₃复合空心球. X射线衍射谱(XRD)表明, 经500 ℃退火制得的ZnO/In₂O₃复合空心球中ZnO以非晶态存在, 但是随着退火温度的提高, 其逐渐转变为纤锌矿结构. 场发射扫描电子显微镜(FE-SEM)和透射显微镜(TEM)结果表明, ZnO/In₂O₃复合材料具有空心球结构, 复合纳米颗粒之间结合紧密. 将ZnO/In₂O₃复合空心球组装成薄膜光电极, 研究了其光电催化降解葡萄糖的性能. 结果表明, 700 ℃退火处理的ZnO/In₂O₃复合空心球薄膜电极可产生最高的光致电流密度. 通过光致发光光谱(PL)发现, 与ZnO或In₂O₃空心球相比, ZnO/In₂O₃复合空心球的发光强度猝灭效果明显. 这是由于复合材料中晶界处产生的p-n结电场, 降低了光生电子-空穴对的复合几率, 从而使更多的光生电子可迁移到电极表面.     

In-situ Study the Corrosion Degradation Mechanism of Tinplate in Salty Water by Scanning Electrochemical Microscopy

In this work, the corrosion degradation of tinplate in contact with salty water is investigated by scanning electrochemical microscopy (SECM) electrochemical impedance spectroscopy (EIS). Experimental results indicate tin maintains at passive state during the exposure; however, pores and defects existed in tin coating leads to an exposure of carbon steel substrate to the electrolyte, in which localized corrosion tends to occur within the pore. A phenomenological model is proposed to interpret corrosion mechanism of tinplate in contact with salty food based on the proposed electrochemical equivalent circuit.     

Electrochemical corrosion kinetics of tin and tin amalgams in NaCl aqueous solutions

Electrochemical techniques were used to determine the corrosion rate of pure tin metal as compared to 80 Sn/20 Hg tin amalgam. X-ray diagrams showed that this amalgam was a crystalline γ₂ phase, whereas a 50 Sn/50 Hg amalgam contained liquid alloy embedded in the same γ₂ phase. Open circuit potential measurements, combined with narrow range potential scanning voltammetry, lead to the conclusion that amalgamation resulted in enhancement of the corrosion current, mainly by increasing the cathodic electron transfer reaction kinetics both in deaerated and in oxygen-saturated NaCl solution. When maintained at zero current potential in a solution containing dissolved O₂ gas, the samples were gradually covered with an insulating oxide layer which was identified by a series of electrochemical impedance diagrams recorded at different time intervals. The oxide layer was firmly adherent to the bulk tin metal but was poor at protecting the amalgam electrode. Finally, at potential values where the anodic current reached a few mA/cm², the pure tin metal surface was suddenly deteriorated by the formation of extremely deep pinhole corrosion pits, while this effect was smoothed down by amalgamation. Electronic Publication     

Chemical deposition of zirconium doped tin silicate ion-exchanger and its characterization

Doping of inorganic ion-exchange material tin silicate with zirconium ion by sol-gel technique was conducted for the production of a novel ion-exchanger. Undoped and doped tin silicate has been characterized by elemental analysis (X-ray fluorescence), Fourier transform infrared spectroscopy (FT-IR), thermal analysis and X-ray diffraction studies. The structures of two ion-exchangers were identified and the empirical formulas found as SnSi₂O₆·6H₂O and SnZr₄Si₄O₁₂·16H₂O for tin silicate and zirconium doped tin silicate, respectively. The effect of zirconium ion concentration of the doped tin silicate on the crystalline size and strain of tin silicate was investigated. The probable structure of both materials was assessed by the ChemDraw Ultra program. Finally, application of these materials for the treatment of radionuclides in terms of capacity measurements was investigated.     

Size-controlled synthesis of SnO2 nanoparticles using reverse microemulsion method

Tin oxide nanoparticles were prepared using an ionic surfactant (sodium dodecyl sulfate) and tin (IV) chloride as an inorganic precursor via the reverse microemulsion method. The size of the nanoparticles is controlled by variation of water-to-surfactant ratio. Eliminating of surfactant in prepared nanoparticles was confirmed by the infrared spectroscopy after sequential calcinations. Transmission electron microscopy, surface area, pore volume, average pore diameter, pore size distribution and X-ray diffraction results were used for evaluation of size distribution, shape and structure of prepared SnO₂ nanoparticles. Transmission electron micrographs confirmed that the obtained materials are spherical nanoparticles. The X-ray diffraction results show the crystalline phases of all samples are SnO₂ with tetragonal structured crystal. In addition, the X-ray diffraction and transmission electron microscopy data showed that the size of SnO₂ nanoparticles decreased with decreasing the water-to-surfactant ratio.     

The effect of cerium pre-treatment on the corrosion resistance of steel sheets

The steel samples have been coated with cerium layer by cathodic electrolytic deposition from the Ce(NO₃)₃·6H₂O solution in aqueous ethyleneglycol in the presence of hydrogen peroxide. The influence of the coating parameters (cathodic current density, pH, cerium concentration, hydrogen peroxide concentration, temperature, and treatment duration) on the surface properties; the optimum conditions of the formation of corrosion preventing coating have been elucidated. Hydrogen peroxide concentration and pH are the major factors influencing the deposition process. The corrosion resistance has been further enhanced after treatment with Na₃PO₄·12H₂O solution. The cerium-coated samples have been subsequently coated by cathodic electrostatic deposition from the colloidal solution of the paint. The coated materials have been subjected to mechanical testing (hardness, impact, cross cut, bending, and cupping tests), and their structure has been visualized by electron microscopy. The cerium coating has been found to improve the steel corrosion resistance by 15%.     

花瓣状微球MoS2/石墨烯复合材料的制备及其电化学性能

采用有利于二维层状结构形成的L-半胱氨酸作为硫源,钼酸钠作为钼源,制备聚乙烯基吡咯烷酮（PVP）辅助水热合成花瓣状微球形貌的MoS₂/还原氧化石墨烯复合电极材料（PVP-MoS₂/RGO）. X射线衍射（XRD）及透射电子显微镜（TEM）证实,经过PVP的适量添加,MoS₂有序堆垛结构的片层数目明显减少. 扫描电子显微镜（SEM）显示,添加适量PVP的MoS₂/石墨烯材料具有分散性更好的花瓣状微球形貌. 上述的少层有序堆垛结构及复合材料的良好分散性缩短了MoS₂中锂离子的嵌入/脱出路径,使其具有更高的容量、循环稳定性和倍率性能.     

Novel Tin Structure Motives in Superconducting BaSn5 – The Role of Lone Pairs in Intermetallic Compounds [1]

BaSn₅ is the tin richest phase in the system Ba/Sn and is obtained by stoichiometric combination of the elements. The compound peritecticly decomposes under formation of BaSn₃ and a Sn–Ba melt at 430 °C. The structure shows a novel structure motive in tin chemistry. Tin atoms are arranged in graphite‐like layers (honeycombs). Two such layers form hexagonal prisms which are centered by Sn. Consequently the central tin atom has the unusual coordination number 12. The two‐dimensional tin slabs which consist of two 3⁶ and one 6³ nets of Sn atoms are separated by 6³ nets of Ba atoms with Ba above the center of each tin hexagon. The structure of BaSn₅ can be rationalized as a variante of AlB₂ and thus also of the superconducting MgB₂. Temperature dependent magnetic susceptibility measurements show that BaSn₅ is superconducting with T_c = 4.4 K. Reinvestigation of the magnetism of the Ba richer phase BaSn₃ reveals for this compound a T_c of 2.4 K. LMTO band structure and density of states calculations verify the metallic behavior of BaSn₅. The van Hove scenario of high‐temperature cuprate superconductors is discussed for this ‘classical' intermetallic superconductor. An analysis of the electronic structure with the help of fat‐band projections and the electron localization function (ELF) shows that the van Hove singularity in the DOS originates from non‐bonding (lone) electron pairs in the intermetallic phase BaSn₅. The role of lone pairs in intermetallic phases is discussed with respect to superconducting properties.     

Detection of Carbon Monoxide in Humid Air with Double-Layer Structures Based on Semiconducting Metal Oxides and Silicalite

Double-layer structures based on gas-sensitive semiconducting metal oxides and silicalite-1 were tested in detection of carbon monoxide in humid air. Pure tin dioxide and that modified with antimony and palladium served as materials of the sensitive layer. Upon deposition of a silicalite-1 layer on SnO₂ and SnO₂/PdO_x, the signal for CO in dry air at room measurement temperature (T = 25°C) grows, but an increase in the air humidity results in that the sensor sensitivity fully disappears. Raising the measurement temperature to 100°C makes weaker the adverse effect of the humidity. The double-layer structure containing the SnO₂(Sb)/PdO_x nanocomposite is characterized by the most stable sensor signal that is independent of the air humidity within the range RH = 4?65%.     

Fabrication and photocatalytic properties of SnO2 double-shelled and triple-shelled hollow spheres

SnO₂ double-shelled and triple-shelled hollow spheres were tailored by adjusting concentration of tin (IV) chloride solution during the process of the tin (IV) ions infused carbonaceous spheres. The structures of these SnO₂ multi-shelled hollow spheres were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and their possible formation mechanism were also discussed. In virtue of triple-shelled hollow porous structure and higher specific surface area, SnO₂ triple-shelled hollow spheres exhibited enhanced photocatalytic properties compared to SnO₂ double-shelled hollow spheres.     

Microwave-assisted synthesis of tin sulfide nanoflakes and their electrochemical performance as Li-inserting materials

A novel and quick method has been developed for the preparation of tin sulfide (SnS and SnS₂) nanoflakes in high yield (≈93%) by a microwave irradiation technique for 10–40 min. The sulfides were synthesized in a simple domestic microwave oven (DMO) using stannic chloride and stanous chloride as the precursors of tin and thiourea as the precursor of sulfur in ethylene glycol under argon atmosphere. Elemental sulfur and sodium thiosulfate were also tried as precursors of sulfur. The structures, morphologies, compositions, and physical properties of the products were characterized by powder X-ray diffraction (XRD), differential scanning calorimetry, energy dispersive X-ray analysis, transmission electron microscopy, selected area electron diffraction, Raman spectroscopy, and standard electrochemical techniques. The XRD patterns indicate that the as-synthesized product, obtained after microwave irradiation, is crystalline orthorhombic in the case of the SnS phase and amorphous in the case of SnS₂. Heat treatment of this SnS₂ produced a crystalline hexagonal phase. A possible mechanism for the formation of the tin sulfide nanoflakes is proposed herein. The electrochemical performance of these materials as Li-insertion materials was investigated in a number of electrolyte solutions and was found to be highly sensitive to the solution composition. A stable reversible capacity higher than 600 mAh/g could be obtained with SnS electrodes.     

The influence of electronic irradiation of tin on its oxidation

The kinetics of tin oxidation was studied using Auger spectroscopy and characteristic electron energy loss spectroscopy. Studies were performed with continuous electron irradiation (E _p = 1800 eV) and without it depending on exposition in oxygen medium at a 10⁻⁶ torr partial oxygen pressure and room temperature (maximum exposure in oxygen was 3000 Langmuir). Exposition to oxygen at 3000 L was shown to cause the formation of a continuous SnO₂ oxide layer, whereas electron irradiation with the same exposition stimulated the growth of a layer predominantly containing SnO.     

Silver nanowires-copper sulfide core/shell nanostructure for electrochemical supercapacitors

This paper reports the synthesis of a new hybrid core (silver nanowires (AgNWs))/shell (copper sulfide (Cu₂S)) nanostructure using simple and inexpensive drop casting and successive ionic layer adsorption and reaction (SILAR) methods. The effects of the thickness of the Cu₂S shell on the Ag NW core on the electrochemical properties of the nanocomposite were studied by varying the number of SILAR cycles from one to four. The structure and microstructure of the prepared composite nanostructure electrode materials were characterized by X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The AgNW/Cu₂S exhibited a high specific capacitance of 603 Fg^?1 (stainless steel substrate) and 707 Fg^?1 (Ni foam substrate) at a scan rate of 10 mVs^?1 with an energy density of 10.01 Whkg^?1 and 25.33 Whkg^?1 at an applied current of 0.2 mA. This study provides a simple and cost-effective strategy for the fabrication of nanostructured electrodes for supercapacitor applications.     

Effects of hydrogen at high temperature on ZnAl2O4 and Sn−ZnAl2O4

ZnAl₂O₄ and Sn?ZnAl₂O₄ were synthesized by coprecipitation, sol-gel and impregnation methods. These materials were calcined and treated in H₂ at 1073 K. Thermal analysis (DTA and TG), nitrogen physisorption (BET method), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used as characterization techniques. H₂ treatment promoted Al_xZn_y crystallization in the coprecipitated and impregnated samples. When tin was added to zinc aluminate, the tin acted as a protective shell against high-temperature reduction, independently of the preparation technique.