Chemical State Of Sn Research Articles

Electrochemical performance of Fe-doped SnSe material electrodes for supercapacitors

This paper synthesized Fe-doped SnSe nanoparticles (NPs) through the co-precipitation technique. The X-ray diffraction (XRD) confirms the orthorhombic crystal structure of Fe-doped SnSe NPs. The chemical states of Sn, Fe and Se elements were identified by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDAX). The galvanostatic charge-discharge (GCD) was used to measure the power efficiency of Fe-doped SnSe electrodes. The specific capacitance of 1283 F/g at a current density of 5 A/g was obtained using a three-electrode system. Further, the Fe-doped SnSe electrode shows a specific energy (Es) of 64 Whkg−1 at a specific power (Ps) of 1500 Wkg−1, respectively. The Fe-doped SnSe electrode exhibits a capacitance retention of 101 % for 1000 GCD cycles in a two-electrode system. This study confirms that the Fe-doped SnSe electrodes are the substitute and life-lasting electrodes for supercapacitor devices.

Combined effects of substrate temperature and post annealing temperature on structural, optical and electrical properties of Sb-doped SnO2 films

Sb-doped SnO2 (ATO) films have received extensive attention as transparent conductive films, but there is still a lack of in-depth and systematic study on combined effects of substrate temperature (Ts) and annealing temperature (Ta) on their transparent conductive properties. In this study, ATO films were prepared using RF magnetron sputtering at RT∼400 ℃ and subsequently annealed at 200–1000 ℃. The results show that the conductive properties of the films enhance (with a decrease in resistivity from 1.15×10-1 to 2.15×10-3 Ω•cm) and the average visible-light transmittance (TVis) decreases (90.16 → 38.24%) with increase of Ts. With the increase of Ta, the conductive properties of the films prepared at different Ts tend to first enhance and then degrade, and the TVis basically shows a trend of first decreasing and then increasing. After annealing at 600 ℃, the films prepared at RT and 100 ℃ can achieve better comprehensive properties (resistivity of 2.50×10-3 and 1.64×10-3 Ω•cm, carrier concentration of 3.35×1020 and 4.93×1020 cm-3, mobility of 7.73 and 7.76 cm2/V•s, sheet resistance of 84 and 55 Ω/sq., and TVis of 86.63 and 79.50%). In order to explore the intrinsic mechanism of the optical and electrical performance of ATO films changing with Ts and Ta, the preferred orientation, crystallinity, and stress state of the films were analyzed by XRD, and their surface morphology was observed by SEM. Meanwhile, the chemical states of Sn, O and Sb as well as Sb content in the films were analyzed by XPS, and their lattice vibration modes of the film were studied by Raman spectra. Finally, the process-structure-properties correlations were established for the ATO films.

Optoelectronic, photocurrent sensitivity and photocatalytic dye degradation behaviour of spray deposited Cr doped SnO2 thin films

Undoped and SnO2:Cr doped thin films (Cr: 0.25, 0.50, 0.75 and 1 wt%) were deposited by economically home-made spray pyrolysis method. The characteristic behaviour of the deposited films was studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Photoluminescence (PL), Ultraviolet–visible (UV–vis.) spectroscopy, Current-Voltage (I–V) and photocatalytic studies. The XRD analysis confirms the tetragonal rutile structure of SnO2 with predominant orientation along the (2 1 1) plane and the decrease in crystallite size from 48 to 30 nm by Cr-doping. The EDAX and XPS studies reveal the elements and its chemical state of Sn, O and Cr. The SnO2:Cr thin films exhibit an 85% average optical transmittance in the visible region of the electromagnetic spectrum. The SEM micrographs clearly show the well-defined grains with boundaries, and it is evident that grain size drastically reduces from 155 nm to 48 nm as a function of Cr-doping. Photoluminescence analysis confirms the defect-related emission (360 nm, 440 and 490 nm). The photocatalytic activity of all thin films is assessed using malachite green (MG) dye under UV light irradiation. 0.75 wt% Cr-doped SnO2 film shows improved photocatalytic performance (60.37%) than undoped thin film (32.03%). The I–V characteristics of undoped and SnO2:Cr thin films are performed in visible light, showing photo-linear response behaviour. The highest figure of merit (FOM) obtained for SnO2:Cr (0.75 wt%) thin film is 7.07 × 10−6 Ω−1. The obtained values of the FOM and photocatalytic performance are discussed in the context of the suitability of these materials for transparent and conducting window materials in solar cells and photocatalytic degradation applications.

An Extrinsic Faradaic Layer on CuSn for High-Performance Electrocatalytic CO 2 Reduction

An Extrinsic Faradaic Layer on CuSn for High-Performance Electrocatalytic CO ₂ Reduction

Effects of Sn doping on the structural and electrochemical properties of Li1.2Ni0.2Mn0.8O2 Li-rich cathode materials

Micron spherical Sn doping Li1.2Ni0.2Mn0.8O2 cathode materials are synthesized via a carbonate co-precipitation method. The crystal structure and morphology of the pristine and Sn-doping samples are characterized by a joint X-ray diffraction (XRD) Rietveld refinement method and scanning electron microscopy (SEM). It is proved that Sn successfully doped into the aimed materials. X-ray photoelectron spectroscopy (XPS) results demonstrate that the chemical state of Sn is +4. Appropriate doping contents of Sn are beneficial to improve the electrochemical performance, including the capacities and cycling stability. The sample with 1.0mol% Sn delivers high initial discharge capacities and improved rate performance (212.6mAh/g at 0.2C and 137.8mAh/g at 5C, respectively). The capacity retention is 96.2% after 50 cycles at 0.2C. It is very stable for the doped sample with 2.0mol% Sn after 160 cycles at 0.2C, the capacity retention is 98.5%. The discharge capacity decreases markedly with the Sn contents increase to 3.0mol%, since Sn4+ can not participate in electrochemical reaction. Electrochemical impedance spectroscopy (EIS) results demonstrate that the charge transfer resistance of the samples with 1.0-2.0mol% Sn-doping decreases obviously. It reveals that doping with appropriate Sn substitution not only improves the structure stability, but also increases the conductivity, therefore improves their rate capability and cycling stability.

Synthesis and electrochemical performance of Sn-doped Li3V2(PO4)3/C cathode material for lithium ion battery by microwave solid-state technique

Li3V2−xSnx(PO4)3/C cathode materials with uniform and fine particle sizes were successfully and fast synthesized by a microwave solid-state synthesis method. X-ray diffraction patterns demonstrated that the appropriate addition of Sn did not destroy the lattice structure of Li3V2(PO4)3/C, but decreased the unit cell volume. X-ray photoelectron spectroscopy analysis demonstrated that the main chemical state of V in the Li3V1.95Sn0.05(PO4)3/C composite is +3 valence, while the chemical state of Sn in the Li3V1.95Sn0.05(PO4)3/C is +4 valence. Scanning electron microscope analysis illustrated that the addition of Sn slightly affected the morphology of samples. As the cathode materials for Li-ion batteries, Li3V2−xSnx(PO4)3/C (x⩽0.10) exhibited higher discharge capacity and better cycle stability than the pure one. At a discharge rate of 0.5C in the potential range of 2.5–4.5V at room temperature, the initial discharge capacity of Li3V1.95Sn0.05(PO4)3/C was 136mAh/g. The low charge-transfer resistances and large lithium ion diffusion coefficients confirmed that Sn-doped Li3V2(PO4)3/C samples possessed better electronic conductivity and lithium ion mobility. These improved electrochemical performances can be attributed to the appropriate amount of Sn doping in Li3V2(PO4)3/C system by enhancing structural stability and electrical conductivity. The present study also demonstrates that the microwave processing is a fast, simple and useful method for the fabrication of Li3V2(PO4)3/C crystals.

Single-site tin-grafted anatase TiO2 for photocatalytic hydrogen production: Toward understanding the nature of interfacial molecular junctions formed in semiconducting composite photocatalysts

This work focuses on the nature of enhanced H2 production over SnO2/TiO2 composite photocatalysts. Three kinds of Sn-modified TiO2 materials were prepared by different methods. Photocatalytic H2 production from methanol/water solution as a model reaction was used to evaluate the photocatalytic properties of the materials. The chemical states of Sn were characterized in detail by transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption fine structure spectroscopy. The results reveal a Sn nuclearity-dependent enhancement of H2 production over Sn/TiO2 photocatalysts. According to the characterization results, it was well established that the number of TiIV–O–SnIV linkages formed at the TiO2–SnO2 interface determines the enhancement amplitude of H2 production. The photogenerated electrons of TiO2 across the interfacial linkages are transferred into the mononuclear Sn moieties grafted on the (101) and (001) planes, where H2 is presumably released. An interatomic electron transfer pathway for accelerating photocatalytic H2 production over Sn/TiO2 catalysts was proposed based on this work.

Effects of Treatment in Different Atmosphere on Pt3Sn/C Electrocatalysts for Ethanol Electro-oxidation

Pt3Sn/C catalyst was prepared by a modified polyol process and treated in air, H2/Ar, and Ar atmosphere, respectively. XRD analyses indicate that all of these catalysts have face-centered cubic (fcc) crystal structure. Temperature-programmed reduction (TPR) experiments show that more Sn exists in zero-valence in the Ar-treated PtSn catalyst than in the others. Cyclic voltammetry (CV), chronoamperometry (CA) experiments, and the performance tests of direct ethanol fuel cell (DEFC) indicate that the catalytic activity of PtSn/C for ethanol oxidation was affected significantly by the chemical state of Sn in catalyst particles. The as-prepared PtSn/C gives the higher power density, while Ar-treated PtSn/C shows the lower cell performance. It seems that the multivalence Sn rather than the zero-valence Sn in the PtSn catalyst is the favorable form for ethanol oxidation. Energy dispersion X-ray analysis (EDX) of the PtSn/C-as prepared and PtSn/C (after stability test) shows the active species (platinum, tin, and...

Estimation of Chemical States and Carrier Density of Sn-doped In2O3 (ITO) by Mössbauer Spectrometry

Chemical states of Sn in Sn-doped In2O3 (ITO) powders and films were studied by Mossbauer spectrometry. From the deconvolution analysis of the spectra it was found that there were 7- and 8-fold coordinated, electrically inactive Sn4+ species in the host lattice in addition to two electrically active Sn4+ species. The concentration of the electrically inactive dopants and the carrier densities could be estimated by Mossbauer spectra. The estimated carrier densities for the powders and films were in good agreement with the measured values.

Ellipsometry and x-ray photoelectron spectroscopy study of SnO2 reduction at the interface with sputtered a-Si:H

Very thin layers of hydrogenated and unhydrogenated amorphous silicon have been deposited on tin oxide substrates under different temperatures and H2 partial pressures by dc magnetron sputtering. The deposition processes are monitored by real time in situ ellipsometry. We observe the reduction reaction of the SnO2 exposed to a H- or Si-containing deposition flux in the early stages of film growth by real time ellipsometry. The chemical states of Sn at the a-Si:H (or a-Si)/SnO2 interface have been studied by x-ray photoelectron spectroscopy (XPS). XPS confirms that a Si flux alone can reduce SnO2 to elemental Sn, and that this reaction is temperature dependent. However, the contribution of Si is secondary to that of H atoms in the reduction reaction.

Characterization of tin oxide films prepared as gas sensors by conversion electron Mössbauer spectrometry

Mn and Ni oxides incorporated tin oxide films, prepared by a spray pyrolysis technique and treated in hydrogen atmospheres, were characterized by conversion electron Mossbauer spectrometry and electron spin resonance to study the gas-sensing mechanism of tin oxides by the addition of metal oxides. Although the chemical state of Sn in undoped tin oxide film did not change after treatment with 5% H2 at 400°C, the reduced Sn species was detected in the tin oxide films doped with Pd. In Sn-Mn oxide films with the addition of Pd, the chemical state of Sn did not change, but the state of Mn changed on exposure to H2. In Sn-Ni oxide films with and without Pd, the chemical states of Sn and Ni were strongly affected by H2. A mechanism of hydrogen spillover effect on the tin oxide films is discussed.

Effect of chemical state of doped Sn on the electrical properties of sputtered ITO films

In order to define the role of doped Sn in highly-conducting sputtered indium tin oxide (ITO) films, the chemical state of Sn in the films and ITO targets has been investigated. The ITO films were prepared by dc magnetron sputtering from a sintered target comprised of a mixture of In 2O 3 and SnO 2. The chemical state of Sn in In 2O 3 was determined by Mössbauer spectroscopy and chemical analysis, and was classified as being one of two groups: SnO 2 grain segregated in In 2O 3, or Sn solved in In 2O 3 structure. ITO films a lower electrical resistivity exhibited higher solubility of Sn in In 2O 3. Lastly, the relation between the film properties and the chemical state of Sn in the targets is discussed.