Sn Oxide Research Articles

高能量密度锂离子电池薄膜负极材料的研究进展

Thin film anode materials in which the active materials were directly deposited on the current collectors are very important for the study and improvement of properties for the new type electrode materials, as well as the application of the thin film micro-batteries. This article summarizes the recent research progress in the thin film anode materials of lithium-ion batteries with high energy densities, which mainly emphasized on preparation, microstructure design and performance enhancement of the Si-, Sn-based alloys and composites, as well as various transition metal oxide thin films with some recent works made in this field by our group. Accordingly, several points for the high energy density thin film anodes were concluded as follows. Nanocrystalline and amorphous structure as well as micro-nano structure tuning could much improve the structure and cycling stability of the pure Si thin film anodes. The cycle performance of Sn-based and Si-based alloy thin films could be enhanced however at the expense of their capacities due to combining with inactive metals. The issues of large initial irreversible capacity loss for the Sn oxide nanocomposites have to be resolved. Most of the nanostructured transition metal oxide thin films had high reversible capacity and good cycleablity, however, their high lithiation/delithiation potentials would lower down the energy density of the battery system. Finally, the article also points out that there are still many practical challenges in the high energy density thin film anode, which could be overcome by further exploration of new-type electrode material systems.

Triblock polymer mediated synthesis of Ir–Sn oxide electrocatalysts for oxygen evolution reaction

Over the past several decades, tremendous effort has been put into developing cost-effective, highly active and durable electrocatalysts for oxygen evolution reaction (OER) in the proton exchange membrane water electrolyzer. This report explores an advanced and effective “soft” material-assistant method to fabricate Ir0.6Sn0.4O2 electrocatalysts with a 0.6/0.4 ratio of Ir/Sn in precursors. Adopting a series of characterization methods, the collective results suggest that the surfactant-material F127 content, as an important factor, can efficiently control the formation of Ir–Sn oxides with varying surface properties and morphologies, such as the grainy and rod-shaped structures. Associating with the half-cell and single electrolyzer, it is affirmed that the optimal ratio of (Ir + Sn)/F127 is 100 for the preparation of S100-Ir0.6Sn0.4O2 with obviously enhanced activity and sufficient durability under the electrolysis circumstances. The lowest cell voltages obtained at 80 °C are 1.631 V at 1000 mA cm−2, and 1.820 V at 2000 mA cm−2, when applying S100-Ir0.6Sn0.4O2 OER catalyst and Ti-material diffusion layer on the anode side and Nafion® 115 membrane. Furthermore, the noble-metal Ir loading in the same cell decreases to 0.77 mg cm−2. These results highlight that Ir–Sn oxide synthesized by the soft-material method is a promising OER electrocatalyst.

Investigation on the Temperature Dependence of the Performance of Solution Processed Si–Zn–Sn Oxide Thin Film Transistor

The performance of the oxide thin film transistors (TFTs) using silicon zinc tin oxide (SZTO) as active channel layer fabricated by solution process method has been reported investigated depending on the annealing temperature. The SZTO TFTs fabricated on silicon wafers exhibit a mobility of 0.591 cm2/Vs, a subthreshold swing (S.S) of 0.44 V/decade, a threshold voltage of 0.7 V and an I(on/off) ratio of 4.4 x 10(6).

PtSn/C catalysts for ethanol oxidation: The effect of stabilizers on the morphology and particle distribution

PtSn/C catalysts are synthesized by using four stabilizers, i.e., ethylene diamine tetra-acetic acid (EDTA), sodium citrate (NaCitrate), glycine and P-aminobenzoate (PABA) with the same reducing process and reaction parameters. XRD characterization shows all PtSn/C catalysts possess face-centered cubic structure with different alloying degree. TEM results show that stabilizers have a significant impact on the morphology and particle size distribution. PtSn/C EDTA and glycine have good particle dispersion with sphere and short nanowire morphology, while obvious particle agglomeration occurred on PtSn/C NaCitrate and PtSn/C PABA. Electrocatalytic activities of these PtSn/C catalysts for ethanol electrooxidation are also measured by cyclic voltammetry. Enhancement of electrocatalytic activity is ascribed to the high particle distribution of PtSn nanoparticles on the carbon supports, not the alloying degree of PtSn nanoparticles. The difference of glycine activities between PtSn/C EDTA and PtSn/C glycine could be ascribed to the variation in the amount of Sn oxides on the surface and density of inter-grain boundary regions in PtSn nanoparticles.

Inherent superhydrophobicity of Sn/SnOx films prepared by surface self-passivation of electrodeposited porous dendritic Sn

Superhydrophobic Sn/SnOx (x=1 and 2) films were facilely fabricated by surface self-passivation of three-dimensional (3D) hierarchical porous dendritic Sn while exposed to the air. The porous dendritic Sn was obtained rapidly by electrodeposition accompanying release of hydrogen bubbles. Influence of electrodeposition parameters on the surface morphology and wettabillity has been investigated in detail, including deposition potentials, deposition times and electrolyte concentrations. The maximum contact angle reached to 165° on the porous dendritic Sn/SnOx film electrodeposited in a solution of 60mM SnCl2 and 1.5M H2SO4 under −1.7V for 20s. Both the hierarchical micro-nanostructures and the spontaneously formed ultrathin surface passivation layer of Sn oxides endow the prepared Sn/SnOx surface with excellent inherent superhydrophobicity without further surface modification.

Selective and stable bimetallic PtSn/θ-Al2O3 catalyst for dehydrogenation of n-butane to n-butenes

PtSn/θ-Al2O3 with various Pt and Sn compositions was prepared by a co-impregnation method using θ-Al2O3 support for n-butane dehydrogenation reaction. The monometallic Pt1.5/θ-Al2O3 catalyst showed severe deactivation in n-butane dehydrogenation. The bimetallic PtSn/θ-Al2O3 catalyst improved the n-C42− yield and the stability. The compositions listed in order of n-C42− yield at 823K are as follows: (PtSn)1.5>(PtSn)1.0>(PtSn)2.0>(PtSn)0.5>Pt1.5>Sn1.5. The n-C42− yields increased with the specific metal surface area. The Sn loading was varied on the Pt1.5 loaded catalyst. Then, the compositions listed in order of n-C42− yield at 823K were as follows: (PtSn)1.5>Pt1.5Sn1.0>Pt1.5Sn2.0>Pt1.5Sn0.5>Pt1.5. The n-C42− yield was maximized at a Pt/Sn weight ratio of 1.0. The n-C42− selectivity of the Pt1.5 catalyst was substantially improved by the Sn addition. TEM and XRD studies indicated PtSn alloy formation on the bimetallic PtSn catalysts during the reduction. The PtSn alloy can increase the n-C42− selectivity by blocking the cracking and hydrogenolysis sites of the Pt catalyst. TPR and HAADF STEM-EDS studies suggest the reduction procedure of the Pt and Sn species. The scattered Pt oxides in the vicinity of the well-dispersed Sn oxides were co-reduced, and then the reduced Sn metals migrated to the PtSn particles, resulting in a PtSn alloy. The specific metal surface area of the Pt1.5 sample was much lower than that of the (PtSn)1.5 sample. Therefore, it can be suggested that Pt metal sintering can be retarded by PtSn alloy formation during the reduction, resulting in high specific metal surface area. These observations demonstrate that the addition of Sn can enhance the activity and n-C42− selectivity.

Toward Functional Polyester Building Blocks from Renewable Glycolaldehyde with Sn Cascade Catalysis

Having been inspired by formose-based hypotheses surrounding the origin of life, we report on a novel catalytic route toward a series of recently discovered four-carbon α-hydroxy acids (AHA) and their esters from accessible and renewable glycolaldehyde (GA) in various solvents. The synthesis route follows a cascade type reaction network, and its mechanism with identification of the rate-determining step was investigated with in situ 13C NMR. The mechanistic understanding led to optimized reaction conditions with higher overall rates of AHA formation by balancing Brønsted and Lewis acid activity, both originating from the tin halide catalyst. An optimal H+/Sn ratio of 3 was identified, and this number was surprisingly irrespective of the Sn oxidation state. Further rate enhancement was accomplished by adding small amounts of water to the reaction mixture, boosting the rate by a factor of 4.5 compared with pure methanol solvent. The cascade reaction selectively yields near 60% methyl-4-methoxy-2-hydroxybutanoate (MMHB). In the optimized rate regime in methanol, an initial TOF of 7.4 molGA molSn–1 h–1 was found. In sterically hindered alcohols (isopropyl alcohol), the rate of AHA formation was even higher, and the corresponding vinyl glycolate esters arose as the main product. Vinyl glycolic acid, 2,4-dihydroxybutanoic acid, and its lactone were formed significantly in nonprotic solvent. The corresponding AHAs have serious potential as building blocks in novel biobased polymers with tunable functionality. The incorporation of vinyl glycolic acid in polylactic acid-based polyesters is illustrated, and postmodification at the vinyl side groups indeed allows access to a range of properties, such as tunable hydrophilicity, which is otherwise difficult to attain for pure poly(l-lactic acid).

Gas sensing of Au/n-SnO2/p-PSi/c-Si heterojunction devices prepared by rapid thermal oxidation

Transparent and conducting SnO2 thin film has been produced on (quartz, ITO, silicon and porous silicon) substrates using rapid photothermal oxidation of pure Sn in air at 600 °C oxidation temperature and different oxidation time. The structural, optical, electrical properties, scan electron microscope and atomic force microscope of the prepared films were studied. The transmittance T in the visible and NIR was investigated; the allowed direct energy gap was determined to be 3.18 eV at optimum condition of 600 °C and 90 s. The dependence of the resistivity on the film thickness and oxidation time has been studied. The optimum thickness of high transmittance and lowest resistivity is about 150 nm for SnO2, where ρ = 1.7 × 10−3 Ω cm and T = 88 %. The sensitivity behaviors of the n-SnO2/p-PSi/c-Si-based gas sensor to H2 and CO2 gas were investigated. The film sensitivity dependence on the temperature and test gas concentration was tested and the optimum operation temperature was determined at around 250 and 300 °C with an applied voltage was constant at 2.5 V.

Morphotropy, isomorphism, and polymorphism of Ln 2 M 2O7-based (Ln = La-Lu, Y, Sc; M = Ti, Zr, Hf, Sn) oxides

Structural studies of compounds of variable composition and measurements of their conductivity have made it possible to identify new oxygen-ion-conducting rare-earth pyrochlores, Ln2Ti2O7 (Ln = Dy-Lu) and Ln2Hf2O7 (Ln = Eu, Gd), with intrinsic high-temperature oxygen ion conductivity (up to 1.4 × 10−2 S/cm at 800°C). Twenty six systems have been studied, and more than 50 phases based on the Ln2M2O7 (Ln= La-Lu; M = Ti, Zr, Hf) oxides have been synthesized and shown to be potential oxygen ion conductors. The morphotropy and polymorphism of the Ln2M2O7 (Ln = La-Lu; M = Ti, Zr, Hf) rare-earth pyrochlores have been analyzed in detail for the first time. Thermodynamic and kinetic (growth-related) phase transitions have been classified with application to the pyrochlore family.

X-ray photoelectron spectroscopy studies of the electronic structure of superconducting Nb2SnC and Nb2SC

Abstract X-ray photoelectron spectroscopy (XPS) was used to investigate the binding energies and valence band of the Nb 2 SnC and Nb 2 SC compounds. The Nb 3d 5/2 , Sn 3d 5/2 , S 2p 3/2 and C 1s core levels associated with the chemical states of Nb 2 SnC and Nb 2 SC were identified. The spectra for Nb 2 SnC revealed Nb and Sn oxides on the surface of the sample, mainly Nb 2 O 5 and SnO 2 , while the Nb 2 SC only Nb 2 O 5 oxide. After Ar + ion etching the intensity of the oxides decreased in both samples. Comparing the Nb 3d, Sn 3d, S 2p and C 1s core levels with metallic Nb, Sn, S and C reference materials, we observed a positive chemical shift for Nb 3d 5/2 and a negative chemical shift for C 1s in both samples. These results suggest that the charge transfer model can be applicable to the Nb 2 SnC and Nb 2 SC compounds. Finally, the decrease in the T c in the Nb 2 SC compound respect to Nb 2 SnC might be associated to decrease in the density of states N ( E F ).

Preparation and evaluation of carbon-supported catalysts for ethanol oxidation

Supported PtSnIr/C, PtSn/C, and IrSn/C catalysts with potential application in a direct alcohol fuel cell were prepared by chemical reduction employing Pechini methodology. The catalyst particles were characterized by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy (XPS). Linear sweep voltammetry (LV), chronoamperometry, and electrochemical impedance spectroscopy (EIS) measurements were performed by using a glassy carbon working electrode covered with the catalyst in a 1 M ethanol + 0.5 M H2SO4 solution at 60 °C. It was demonstrated through XPS that PtSnIr/C and IrSn/C contain both IrO2 and SnO2. LV and chronoamperometry show a better catalytic behavior for ethanol oxidation on PtSnIr/C in the low-potential region and the improvement is attributed to the presence of both Sn and Ir oxides. The EIS accurately established that PtSnIr/C improved ethanol oxidation at lower potentials than PtSn/C.

Anodic formation of self-organized Ti(Nb,Sn) oxide nanotube arrays with tuneable aspect ratio and size distribution

In the present communication one-step anodization is used to prepare large arrays of self-assembled Ti(Nb,Sn) oxide nanotubes on Ti–Nb–Sn alloy. Tuneable nanoscale geometries (unimodal vs. bimodal size distribution with variable length/diameter ratios) can be controllably achieved by varying the anodization conditions, which are highly desirable for enhanced functionalities in widespread applications.

SnO2/CuO nano-hybrid foams synthesized by electrochemical deposition and their gas sensing properties

SnO2/CuO nano-hybrid foam sensors were fabricated through thermal oxidation of Sn–Cu foam synthesized by electrochemical deposition, and their gas sensing properties were investigated. The macro-porous Sn–Cu foam was formed during electrodeposition, and its pore wall was composed of self-supported nano-sized dendrites. The annealing at 700°C converted the Sn–Cu foam into the SnO2/CuO nano-hybrid foam with preserving the structural integrity and pore structure. The SnO2/CuO nano-hybrid foam sensor responded to the reducing gases such as H2, CO, NH3, NOx, CH5OH, and H2S, but the foam sensor exhibited two orders of magnitude higher gas response toward H2S. The enhanced sensitivity and selectivity toward H2S gas can be attributed to the formation of resistive p-CuO/n-SnO2 junction in nano-scale.

Effect of Indium Content on the Melting Point, Dross, and Oxidation Characteristics of Sn-2Ag-3Bi-xIn Solders.

This paper presents the effect of indium (In) content on the melting temperature, wettabililty, dross formation, and oxidation characteristics of the Sn-2Ag-3Bi-xIn alloy. The melting temperature of the Sn-2Ag-3Bi-xIn alloy (2 ≤ x ≤ 6) was lower than 473 K. The melting range between the solidus and liquidus temperatures was approximately 20 K, irrespective of the indium content. As the indium content increased, the wetting time increased slightly and the maximum wetting force remained to be mostly constant. The dross formation decreased to approximately 50% when adding 1In to Sn-2Ag-3Bi, and no dross formation was observed in the case of Sn-2Ag-3Bi-xIn alloy (x ≥ 1.5) at 523 K for 180 min. Upon approaching the inside of the oxidized solder of the Sn-2Ag-3Bi-1.5In alloy from the surface, the O and In contents decreased and the Sn content increased based on depth profiling analysis using Auger electron spectroscopy (AES). The mechanism for restraining dross (Sn oxidation) of Sn-2Ag-3Bi alloy with addition of indium may be due to surface segregation of indium. This is due to the lower formation energy of indium oxide than those of Sn oxidation.

In Situ Observation of Tin Negative Electrode / Electrolyte Interface by X-ray Reflectivity

An electrode/electrolyte interface is obviously one of the most dominant factors controlling a battery performance. In the present work, a formation of a tin negative electrode/electrolyte interface (SEI) was investigated by an in situ X-ray reflectivity measurement. SEI was formed even at a high voltage of about 2.5 V vs Li/Li+. This voltage is much higher than the value of about 1.5 V in the previous works. Thus, SEI in the present work is clearly different from that formed by reductive decomposition of an electrolyte and/or reduction of Sn oxide. Its structure was seemingly an amorphous solid containing a quite amount of fluoride, which grows up to 150-200 nm thick by keeping for 1 h at about 2.5-2.6 V.

Corrosion Behavior of Pb-Free Sn-1Ag-0.5Cu-XNi Solder Alloys in 3.5% NaCl Solution

Potentiodynamic polarization techniques were employed in the present study to investigate the corrosion behavior of Pb-free Sn-1Ag-0.5Cu-XNi solder alloys in 3.5% NaCl solution. Polarization studies indicated that an increase in Ni content from 0.05 wt.% to 1 wt.% in the solder alloy shifted the corrosion potential (Ecorr) towards more negative values and increased the linear polarization resistance. Increased addition of Ni to 1 wt.% resulted in significant increase in the concentration of both Sn and Ni oxides on the outer surface. Secondary-ion mass spectrometry and Auger depth profile analysis revealed that oxides of tin contributed primarily towards the formation of the passive film on the surface of the solder alloys containing 0.05 wt.% and 1 wt.% Ni. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) established the formation of a Sn whisker near the passive region of the solder alloy obtained from the polarization curves. The formation of Sn whiskers was due to the buildup of compressive stress generated by the increase in the volume of the oxides of Sn and Ni formed on the outer surface. The presence of Cl− was responsible for the breakdown of the passive film, and significant pitting corrosion in the form of distinct pits was noticed in Sn-1Ag-0.5Cu-0.5Ni solder alloy after the polarization experiment.

Synthesis and performance of Pd/SnO2–TiO2/MWCNT catalysts for direct formic acid fuel cell application

A simple and controllable in situ chemical method for preparing Palladium/Tin oxide-titanium dioxide/multi-walled carbon nanotube (Pd/SnO2–TiO2–MWCNTs) catalysts for direct formic acid oxidation is proposed in this study. The electro-oxidation of formic acid can be promoted by the addition of SnO2. Transmission electron microscopy (TEM) showed that Pd particles were homogeneously distributed on the surface of the SnO2–TiO2 surface. Cyclic voltammetry indicated that a much greater enhancement in catalytic activity (3.6 times) was observed when compared with the improvement in ESA value (1.8 times). The results of the electrochemical impedance spectroscopy showed that the enhanced CO tolerance may be attributed to the synergetic effect between the Pd and Sn oxides.

Effect of oleic acidligand on photophysical, photoconductive and magnetic properties of monodisperse SnO2quantum dots

Oleic acid capped monodisperse SnO(2) quantum dots (QDs) of size 2.7 nm were synthesized by thermal decomposition and oxidation of Sn(II)(oleate) complex in high boiling nonpolar solvent octadecene using oleic acid as a capping agent and N-methylmorpholine N-oxide as an oxidizing agent. FTIR, DSC and TGA were employed to understand the growth of the oleic acid capped SnO(2) QDs through the decomposition of metal fatty acid complex. The surface defect-related luminescence properties of the QDs were demonstrated using steady-state and time-resolved spectroscopy. The oleic acid capping on the QD surface modifies the electronic structure of SnO(2) and generates blue emission. Moreover the surface capping on the QDs diminishes the photocatalytic activity of bare SnO(2) QDs due to absence of surface oxygen and adsorbed hydroxyl group on the surface of the capped QDs. The capping by the long chain ligand oleic acid makes the SnO(2) QDs less conducting. Ligand exchange of the long chain oleic acid (2.5 nm) by the short chain n-butylamine (0.6 nm) increases the current density of SnO(2) around 43 times due to the reduction of the interparticle distance. Ferromagnetic behaviour of oleic acid capped QDs may be ascribed to the defects in the host due to the alteration of the electronic structure owing to the capping.

Preparation and Characterization of (Au/n-Sn/Si/Si/Al) MIS Device for Optoelectronic Application

SnO₂ thin films were prepared by using rapid thermal oxidation (RTO) of Sn at oxidation temperature 873 K and oxidation time 90 sec on semiconductor n-type and p-type silicon substrate. In order to characterize the prepared device, the electrical properties have been measured which revealed that the barrier height is greatly depended on interfacial layer thickness (SiO₂). The value of peak response (n-SnO₂/SiO₂/n-Si) device was 0.16 A/W which is greater than that of (n-SnO₂/SiO₂/p-Si) device whose value was 0.12 A/W, while the rise time was found to be shorter.

Performance and characterization of a Pt–Sn(oxidized)/C cathode catalyst with a SnO2-decorated Pt3Sn nanostructure for oxygen reduction reaction in a polymer electrolyte fuel cell

We have prepared and characterized a SnO2-decorated Pt-Sn(oxidized)/C cathode catalyst in a polymer electrolyte fuel cell (PEFC). Oxygen reduction reaction (ORR) performance of Pt/C (TEC10E50E) remained almost unchanged or even tended to reduce in repeated I-V load cycles, whereas the I-V load performance of the Pt-Sn(oxidized)/C prepared by controlled oxidation of a Pt-Sn alloy/C sample with the Pt3Sn phase revealed a significant increase with increasing I-V load cycles. The unique increase in the ORR performance of the Pt-Sn(oxidized)/C catalyst was ascribed to a promoting effect of SnO2 nano-islands formed on the surface of Pt3Sn core nanoparticles. Also in a rotating disk electrode (RDE) setup, the mass activity of an oxidized Pt3Sn/C catalyst was initially much lower than that of a Pt/C catalyst, but it increased remarkably after 5000 rectangular durability cycles and became higher than that of the fresh Pt/C. The maximum power density per electrochemical surface area for the Pt-Sn(oxidized)/C catalyst in a PEFC was about 5 times higher than that for the Pt/C catalyst at 0.1-0.8 A cm(-2) of the current density. In situ X-ray absorption near-edge structure (XANES) analysis at the Pt LIII-edge in increasing/decreasing potential operations and at the Sn K-edge in the I-V load cycles revealed a remarkable suppression of Pt oxidation compared with the Pt/C catalyst at higher potentials and no change in the Sn oxidation state, respectively, resulting in higher performance and stability of the Pt-Sn(oxidized)/C catalyst due to the SnO2 nano-islands under the PEFC operation conditions. The SnO2 nano-island decorated Pt-Sn(oxidized)/C catalyst with a Pt3Sn alloy nanostructure is regarded as a promising candidate for a PEFC cathode catalyst.