Cassiterite SnO2 Research Articles

Preparation of SnO2 Nanoparticles with Addition of Co Ions for Photocatalytic Activity of Brilliant Green Dye Degradation

Pure and cobalt (Co)-doped tin oxide (SnO2) nanoparticles were prepared by using a simple co-precipitation method, and the effect of doping on structural, morphological and optical properties was studied. X-ray diffraction revealed a cassiterite tetragonal SnO2 structure with the space group of P42/mnm and without crystalline phases for the samples-doped with higher concentrations. The average crystalline size was found to be between 26.4 nm and 23.1 nm. Fourier-transform infrared spectra depicted the presence of O–H, C–H and Sn–OH absorption bands. It was observed from ultraviolet–visible spectra that the optical band gap values were decreased from 3.69 eV for pure SnO2 to 3.47 eV for 7% Co-doped SnO2. The photolumenescene emission spectra showed that the defect- and emissions-related peaks and the intensity of the peaks decreased with increasing Co concentrations. The presence of tin, oxygen and Co species were found from energy dispersive x-ray spectra. The photocatalytic activities of pure and Co-doped SnO2 nanoparticles were investigated by studying the photodecomposition of brilliant green dye, an organic pollutant. The 7% Co-doped SnO2 had higher photocatalytic activity compared to the pure SnO2, and a maximum degradation efficiency of 91% has been obtained under visible light irradiation.

Role of the growth step on the structural, optical and surface features of TiO2/SnO2 composites.

TiO2/SnO2 composites have attracted considerable attention for their application in photocatalysis, fuel cells and sensors. Structural, morphological, optical and surface features play a pivotal role in photoelectrochemical applications and are critically related to the synthetic route. Most of the reported synthetic procedures require high-temperature treatments in order to tailor the sample crystallinity, usually at the expense of surface hydroxylation and morphology. In this work, we investigate the role of a treatment in an autoclave at a low temperature (100°C) on the sample properties and photocatalytic performance. With respect to samples calcined at 400°C, the milder crystallization treatment promotes anatase phase, mesoporosity and water chemi/physisorption, while reducing the incorporation of heteroatoms within the TiO2 lattice. The role of Sn content was also investigated, showing a marked influence, especially on the structural properties. Notably, at a high content, Sn favours the formation of rutile TiO2 at very low reaction temperatures (100°C), thanks to the structural compatibility with cassiterite SnO2. Selected samples were tested towards the photocatalytic degradation of tetracycline in water under UV light. Overall, the low-temperature treatment enables to tune the TiO2 phase composition while maintaining its surface hydrophilicity and gives rise to well-dispersed SnO2 at the TiO2 surface.

Surface studies of patinas and metallurgical features of uncommon high-tin bronze artefacts from the Italic necropolises of ancient Abruzzo (Central Italy)

Archaeological high-tin copper-based artefacts, dated back to VIII and IV centuries BC and recently discovered in the Italic necropolises of ancient Abruzzo (Central Italy), were investigated in order to determine the micro-chemical and micro-structural nature of the corrosion products and the chemical composition and metallurgical features of the alloys. The Cu-based artefacts were defensive weapons mainly as bronze belts and pectoral disc armours with engraved decorations. A rather detailed picture of the chemical composition, structural and morphological characteristics of such Cu-based artefacts was provided by combining different techniques as scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), optical microscopy (OM) and X-ray diffraction (XRD) analysis. The results, as a whole, evidence that some artefacts were manufactured by casting and shaping uncommon high-tin bronze alloys thus conferring an attractive silver-like appearance. The manufacturing process was based on tailored multiple hot hammering, carefully carried out at about 700 °C to shape the high-tin alloys in the form of sheets avoiding breaking. The mechanical work was followed by an annealing treatment, polishing and final decorative finishing. Furthermore, our investigation on the corrosion process, suggest that it is a mixture of rather complex phenomena leading to the degradation of the main alloying elements which give rise to mineral alteration products in the form of complex structures. These latter contain SnO2 (cassiterite), cuprous oxide, copper carbonates (azurite and malachite) and, in particular, chlorine-based compounds like nantokite and atacamite and its polymorphs, which have heavy detrimental effects, their presence being considered a symptom of the destructive “bronze disease” degradation phenomenon. Moreover, it was found an unusual presence of re-deposited Cu inclusions to be likely related to long-term corrosion processes and to a low oxygen availability in the burial environment. All these findings show, as a whole, that there is a strict relationship between alloy elements, metallurgical features, burial soil conditions and chemical and structural features of the corrosion products. This paper highlights also as the combined use of different techniques as SEM-EDS, ATR-FTIR, XPS, XRD and OM can be one of the possible successfully way to study the corrosion products of archaeological copper-based artefacts, thus helping to choose the more appropriate strategies for the long-lasting conservation of archaeological bronze artworks, in most cases so valuable for the cultural heritage.

Finely Tuned SnO2 Nanoparticles for Efficient Detection of Reducing and Oxidizing Gases: The Influence of Alkali Metal Cation on Gas-Sensing Properties.

Tin dioxide (SnO2) nanoparticles were straightforwardly synthesized using an easily scaled-up liquid route that involves the hydrothermal treatment, either under acidic or basic conditions, of a commercial tin dioxide particle suspension including potassium counterions. After further thermal post-treatment, the nanomaterials have been thoroughly characterized by Fourier transform infrared and Raman spectroscopy, powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen sorption porosimetry. Varying pH conditions and temperature of the thermal treatment provided cassiterite SnO2 nanoparticles with crystallite sizes ranging from 7.3 to 9.7 nm and Brunauer-Emmett-Teller surface areas ranging from 61 to 106 m2·g-1, acidic conditions favoring potassium cation removal. Upon exposure to a reducing gas (H2, CO, and volatile organic compounds such as ethanol and acetone) or oxidizing gas (NO2), layers of these SnO2 nanoparticles led to highly sensitive, reversible, and reproducible responses. The sensing results were discussed in regard to the crystallite size, specific area, valence band energy, Debye length, and chemical composition. Results highlight the impact of the counterion residuals, which affect the gas-sensing performance to an extent much higher than that of size and surface area effects. Tin dioxide nanoparticles prepared under acidic conditions and calcined in air showed the best sensing performances because of lower amount of potassium cations and higher crystallinity, despite the lower surface area.

Multi-applicative tetragonal TiO2/SnO2 nanocomposites for photocatalysis and gas sensing

TiO2-based mixed metal oxide heteronanostructures have multiple applications in photocatalysis and gas sensing because of their charge transport properties. In this study, we prepared tetragonal TiO2/SnO2 nanocomposites (NCs) with different weight percentages using a simple wet impregnation method. The physicochemical properties of the NCs were investigated using X-ray diffraction, Fourier transform-infrared spectroscopy, ultraviolet–visible spectroscopy, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, and Brunauer–Emmett–Teller surface area analysis. The results showed that the surface area of the NCs increased significantly and the anatase TiO2 was sensitized after the addition of a small amount of cassiterite SnO2 NPs. We systematically studied the as-prepared NCs during the photocatalytic degradation of Congo Red dye under visible light irradiation (λ > 420 nm) and NH3 gas sensing, which demonstrated the efficient photocatalytic performance and the superior sensing response of the catalyst with a weight composition of 25% SnO2 in TiO2 (4:1) compared with the other NCs or the bare individual nanoparticles. The improved photocatalytic and gas sensing performance of the TiO2/SnO2 (4:1) NCs may be attributed to the increased active surface area, the increased adsorption of the dye and target gas molecules, as well as efficient electron–hole charge separation and transfer.

Investigation of Reduced Graphene Oxide with F-Doped SnO2 as Catalyst Support in Fuel Cells

A main challenge in commercialisation of fuel cells is the performance loss with time of operation. The platinum catalyst is subjected to electrochemical instability, and carbon black as commonly used catalyst support suffers from corrosion.[1,2] To improve the fuel cell stability, alternative support materials can be used. Application of graphene-based carbon in low temperature PEMFCs has demonstrated higher durability than conventional carbon black.[3] The combination with corrosion resistant metal oxides provides additional binding sites for Pt nanoparticles[4,5] and can prevent graphene materials from restacking causing mass transport limitations in fuel cells.[6] In this study, reduced graphene oxide (rGO) is synthesised in two steps. Graphene oxide is received via Hummer’s method[7] and then thermally reduced to rGO. In the following synthesis, fluorine-doped tin (IV) oxide (FTO) nanoparticles are deposited on rGO sheets. Therefore, a sol-gel method using tin tetrachloride precursor followed by addition of NH4F and hydrothermal treatment is carried out on rGO.[8,9] Figure 1a shows the achieved crystalline FTO structure which is similar to cassiterite tin (IV) oxide. Using Scherrer equation an average FTO particle size of 4.8±0.4 nm is calculated. Transmission electron microscopy (TEM) in Figure 1b reveals successful deposition of the FTO nanoparticles on rGO. In the last synthesis step, Pt is precipitated on FTO-rGO via chemical reduction of chloroplatinic acid with ethylene glycol.[4] Then, Pt/FTO-rGO catalyst is intensively investigated for electrochemical stability under fuel cell operation conditions by the use of an accelerated stress test (AST). Within an electrochemical cell the catalyst is exposed to 1,000 potential cycles between -0.02 and 1.40 VRHE at a scan rate of 500 mV s-1under oxygen saturation. To ensure a holistic analysis of possible catalyst and support degradation, this AST is performed twice. During the first test, a rotating disk electrode allows the study of the oxygen reduction reaction (ORR) mechanism and activity at different rotation speeds (400, 900, 1200, 1600, 2000 and 2500 rpm). The electrochemical active surface area (EASA) is carefully determined by hydrogen underpotential deposition as well as carbon monoxide stripping voltammetry. In the second test run, the rotating disk electrode as working electrode is replaced by a catalyst coated grid for identical location TEM analysis. First, the untested Pt/FTO-rGO catalyst on the grid is analysed by TEM and then the catalyst on grid is stressed by exactly the same potential cycling. After performing AST, the same Pt/FTO-rGO particles are investigated again under the microscope. Thus, possible Pt degradation processes like agglomeration can be revealed which allows the supplementation of electrochemical investigations. Fig. 1: XRD pattern of FTO-rGO with comparison to crystalline structure of cassiterite SnO2 (ICDD 98-000-9463) (a) and TEM image of deposited FTO particles on rGO (b). [1] D. Schonvogel, M. Rastedt, P. Wagner, M. Wark, A. Dyck, Fuel Cells 2016, 16, 480-489. [2] Y. Shao-Horn, W. C. Sheng, S. Chen, P. J. Ferreira, E. F. Holby, D. Morgan, Top. Catal. 2007, 46, 285-305. [3] Y. Shao, S. Zhang, C. Wang, Z. Nie, J. Liu, Y. Wang, Y. Lin, J. Power Sources 2010, 195, 4600-4605. [4] R. Kou, Y. Shao, D. Mei, Z. Nie, D. Wang, C. Wang, V. V. Viswanathan, S. Park, I. A. Aksay, Y. Lin, Y. Wang, J. Liu, J. Am. Chem. Soc. 2011, 133, 2541-2547. [5] Y. Liu, W. E. Mustain, J. Am. Chem. Soc. 2013, 135, 530-533. [6] S. Park, Y. Shao, H. Wan, P. C. Rieke, V. V. Viswanathan, S. A. Towne, L. V. Saraf, J. Liu, Y. Lin, Y. Wang, Electrochem. Commun. 2011, 13, 258-261. [7] S. Ratso, I. Kruusenberg, M. Vikkisk, U. Joost, E. Shulga, I. Kink, T. Kallio, K. Tammeveski, Carbon 2014, 73, 361-370. [8] D.-J. Guo, Z.-H. Jing, J. Colloid Interface Sci. 2011, 359, 257-260. [9] H. Xu, L. Shi, Z. Wang, J. Liu, J. Zhu, Y. Zhao, M. Zhang, S. Yuan, ACS Appl. Mater. Interfaces 2015, 7, 27486-27493. Figure 1

Physicochemical model of tin behavior in weathering profiles

Numerical simulations of a weathering profile on granite containing 10–8 mol/L Sn (whose average content in the Earth’s crust is 0.00025%) by the SELECTOR program package indicate that cassiterite SnO2 solubility under both oxidizing and reducing conditions is no higher than 10–10 mol/L within the pH range of 3 to 11. The only ion occurring in equilibrium with cassiterite is the neutral Sn(OH)4(aq) 0 complex, which was detected in both oxidizing and reducing environments.

Inorganic Photocatalytic Enhancement: Activated RhB Photodegradation by Surface Modification of SnO2 Nanocrystals with V2O5-like species

SnO2 nanocrystals were prepared by precipitation in dodecylamine at 100 °C, then they were reacted with vanadium chloromethoxide in oleic acid at 250 °C. The resulting materials were heat-treated at various temperatures up to 650 °C for thermal stabilization, chemical purification and for studying the overall structural transformations. From the crossed use of various characterization techniques, it emerged that the as-prepared materials were constituted by cassiterite SnO2 nanocrystals with a surface modified by isolated V(IV) oxide species. After heat-treatment at 400 °C, the SnO2 nanocrystals were wrapped by layers composed of vanadium oxide (IV-V mixed oxidation state) and carbon residuals. After heating at 500 °C, only SnO2 cassiterite nanocrystals were obtained, with a mean size of 2.8 nm and wrapped by only V2O5-like species. The samples heat-treated at 500 °C were tested as RhB photodegradation catalysts. At 10−7 M concentration, all RhB was degraded within 1 h of reaction, at a much faster rate than all pure SnO2 materials reported until now.

Synthesis of a SnO2/TNT Heterojunction Nanocomposite as a High-Performance Photocatalyst

In this study, high-performance SnO2/TiO2 nanotube (TNT) nanocomposites were prepared through a facile one-step hydrothermal method. The samples retained a high BET surface area because they were calcination-free. The BET surface area of all of the samples was over 300 m2/g, and the length was within 100–200 nm. During the hydrothermal reaction, a heterojunction between the SnO2 and TNTs through oriented attachment was achieved. Additionally, we demonstrate that the introduction of cassiterite SnO2 as a precursor in the hydrothermal process can induce the growth of anatase TiO2. A SnO2/TNT nanocomposite photocatalyst not only facilitated dye adsorption at a high concentration around the surface of the nanocomposites but also exhibited efficient charge separation properties and achieved outstanding photocatalytic performance. This study proposes a simple, cost-effective, and environmentally friendly synthetic strategy for fabrication of TNT-based heterostructures as high-performance photocatalysts through adding precursors in the proper amounts.

Growth, structure and photoluminescence properties of SnO2-ZnO (TZO) micro cubes

Structural investigation from X-ray diffraction patterns of TZO revealed the presence of SnO2 (cassiterite), ZnO (wurtzite) and ZnSnO3 and ZnSnO4 phases. The optical absorption spectra recorded for these powders dispersed in ethanol show the nature of the composite nanopowders to be semiconducting one having an optical absorption band around 280nm. Electron microscopy confirms a change in shape and size of the particles with a change in Sn/Zn ratio. The amorphous nature increases while going from Sn/Zn ratio of 0.87 to 3.75 and cubes of size ∼ 2μm, rhombohedral and irregular shaped particles are also observed. The prepared tin zinc oxide samples (TZO) show excitation bands at 241, 287 and 351 nm and common emission bands at 448, 485, 462 and 531 nm for all excitation energies. The photoluminescence and other studies reveal the role played by composition in changing the shape.

Nanocrystalline TiO2/SnO2 heterostructures for gas sensing.

The aim of this research is to study the role of nanocrystalline TiO2/SnO2 n–n heterojunctions for hydrogen sensing. Nanopowders of pure SnO2, 90 mol % SnO2/10 mol % TiO2, 10 mol % SnO2/90 mol % TiO2 and pure TiO2 have been obtained using flame spray synthesis (FSS). The samples have been characterized by BET, XRD, SEM, HR-TEM, Mössbauer effect and impedance spectroscopy. Gas-sensing experiments have been performed for H2 concentrations of 1–3000 ppm at 200–400 °C. The nanomaterials are well-crystallized, anatase TiO2, rutile TiO2 and cassiterite SnO2 polymorphic forms are present depending on the chemical composition of the powders. The crystallite sizes from XRD peak analysis are within the range of 3–27 nm. Tin exhibits only the oxidation state 4+. The H2 detection threshold for the studied TiO2/SnO2 heterostructures is lower than 1 ppm especially in the case of SnO2-rich samples. The recovery time of SnO2-based heterostructures, despite their large responses over the whole measuring range, is much longer than that of TiO2-rich samples at higher H2 flows. TiO2/SnO2 heterostructures can be intentionally modified for the improved H2 detection within both the small (1–50 ppm) and the large (50–3000 ppm) concentration range. The temperature Tmax at which the semiconducting behavior begins to prevail upon water desorption/oxygen adsorption depends on the TiO2/SnO2 composition. The electrical resistance of sensing materials exhibits a power-law dependence on the H2 partial pressure. This allows us to draw a conclusion about the first step in the gas sensing mechanism related to the adsorption of oxygen ions at the surface of nanomaterials.

Study of tin dioxide–sodium stannate composite obtained by decomposition of peroxostannate as a potential anode material for lithium-ion batteries

A tin dioxide–sodium stannate composite has been obtained by the thermal treatment of sodium peroxostannate nanoparticles at 500°C in air. X-ray powder diffraction study has revealed that the composite includes crystalline phases of cassiterite SnO2, sodium stannate Na2Sn2O5, and sodium hexahydroxostannate Na2Sn(OH)6. Scanning electron microscopy has shown that material morphology does not change considerably as compared with the initial tin peroxo compound. Electrochemical characteristics have been compared for the anodes of lithium-ion batteries based on tin dioxide–sodium stannate composite and anodes based on a material manufactured by the thermal treatment of graphene oxide–tin dioxide–sodium stannate composite at 500°C in air.

Constituent elements and their distribution in the radioactive Cs-bearing silicate glass microparticles released from Fukushima nuclear plant.

Microparticles of radioactive cesium (Cs)-bearing silicate glass emitted from the Fukushima Daiichi nuclear power plant were investigated mainly using state-of-the-art energy-dispersive X-ray spectroscopy in scanning transmission electron microscopes. Precise elemental maps of the particles were obtained using double silicon drift detectors with a large collection angle of X-rays, and qualitative elemental analysis was performed using high-resolution X-ray spectroscopy with a microcalorimetry detector. Beside the substantial elements (O, Si, Cl, K, Fe, Zn, Rb, Sn and Cs) as previously reported, Mn and Ba were also common, though their amounts were small. The atomic ratios of the substantial elements were not the same but varied among individual particles. Fe and Zn were relatively homogeneously distributed, whereas the concentration of alkali ions varied radially. Generally, Cs was rich and K and Rb were poor outward of the particles but the degree of such radial dependence was considerably different among the particles. A concentration of Sn on the particle surface was observed. High-resolution imaging indicated the formation of SnO2 (cassiterite) nanocrystals on the surface. Synthesis of the bulk glass with a similar composition to the microparticles was attempted by quenching the silicate melt from ∼1600°C. However, homogeneous silicate glass like that of the microparticles could not be obtained due to the segregation of nano-spherules rich in Fe and Zn, suggesting that the microparticles were formed in a very specific condition in the nuclear reactor.

The effect of antimony-tin and indium-tin oxide supports on the catalytic activity of Pt nanoparticles for ammonia electro-oxidation

Platinum nanoparticles supported on carbon (Pt/C) and carbon with addition of ITO (Pt/C-ITO (In2O3)9·(SnO2)1) and ATO (Pt/C-ATO (SnO2)9·(Sb2O5)1) oxides were prepared by sodium borohydride reduction method and used for ammonia electro-oxidation reaction (AmER) in alkaline media. The effect of the supports on the catalytic activity of Pt for AmER was investigated using electrochemical (cyclic voltammetry and chronoamperometry) and direct ammonia fuel cell (DAFC) experiments. X-ray diffraction (XRD) showed Pt peaks attributed to the face-centered cubic (fcc) structure, as well as peaks characteristic of In2O3 in ITO support and cassiterite SnO2 phase of ATO support. According to transmission electron micrographs the mean particles sizes of Pt over carbon were 5.4, 4.9 and 4.7 nm for Pt/C, Pt/C-ATO and Pt/C-ITO, respectively. Pt/C-ITO catalysts showed the highest catalytic activity for ammonia electrooxidation in both electrochemical and fuel cell experiments. We attributed this to the presence of In2O3 phase in ITO, which provides oxygenated or hydroxide species at lower potentials resulting in the removal of poisonous intermediate, i.e., atomic nitrogen (Nads) and promotion of ammonia electro-oxidation.

Tin stearate organometallic precursor prepared SnO2 quantum dots nanopowder for aqueous- and non-aqueous medium photocatalytic hydrogen gas evolution

Current study reports a rapid one-pot non-hydrolytic condition in the synthesis of SnO2 QDs nanopowder using tin (II) stearate (Sn(St)2) as environmentally-benign organometallic precursor, which is an unprecedentedly employed-compound in preceding SnO2 nanopowder productions. The as-synthesized SnO2 QDs that are hydrophobic can be easily transferred from organic solvent to aqueous solution through a robust ligand exchange method. The stearate-capping ligands on the surface of QDs can be replaced by beta-cyclodextrin (β-CD) and eventually render the QDs highly water soluble, which ultimately make it exhibit bi-functionality for different liquid medium applications. Structural characterizations reveal that the bi-functional QDs are indeed well-matched with the standard rutile SnO2 cassiterite phase without the presence of any impurities. The QDs can be interchangeably used as photocatalyst for both aqueous and non-aqueous phase, where it shows significant enhancement of hydrogen gas production as compared to that of commercial SnO2 nanopowder.

SnO2 foam grain-shaped nanoparticles: Synthesis, characterization and UVA light induced photocatalysis

Cassiterite (tin oxide; SnO2) nanoparticles (NPs), has been successfully synthesized via a sol-gel method. The obtained compounds are subsequently calcined at 80, 450 and 650 °C for 4 h and are assigned as SnO2-80, SnO2-450 NPs and SnO2-650 NPs, respectively. All prepared samples were characterized using thermogravimetric analysis coupled with mass spectroscopy (TG-SM), X-ray diffraction (XRD), scanning electron microscope (SEM) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The XRD results confirmed the aggregated cassiterite SnO2 nanoparticles (NPs) with a size ranging from 13 to 23 nm. The absorption edge of the SnO2 NPs samples calcined at higher temperatures showed 25 nm (SnO2-450 NPs) and 10 nm (SnO2-650 NPs) red shifted compared with that of commercial SnO2-com NPs sample. The photodegradation efficiency of SnO2 NPs was investigated using Congo red (CR) dye, as model organic pollutant. The effect of environmental factors (e.g., reaction time and calcination temperature) on the photocatalysis process of CR on SnO2 NPs was investigated in photocatalysis process under UVA light irradiation. We found that the SnO2-650 NPs with 23 nm particle size and about 3.49 eV band gap was higher than that of the SnO2-450 as well as the commercial SnO2-com NPs. Pseudo-first-order kinetic model gave the best fit, with highest correlation coefficients (R2 ≥ 0.95). On the basis of the energy band diagram positions, the enhanced photodegradation efficiency SnO2 NPs catalyst could be proceeded via direct reactions with (O2- and OH), as active oxidative species involved in the photocatalysis process of CR dye under UVA-light irradiation.

Preparation and characterization of Ni-doped ZnO–SnO2 nanocomposites: Application in photocatalysis

The paper reports on the synthesis of nickel-doped ZnO–SnO2 nanocomposites with a molar ratio Zn:Sn of 2:1 using the hydrothermal method followed by calcination at 700 °C. The resulting nanocomposites were characterized using X-ray diffraction (XRD) patterns, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and Energy-dispersive X-ray spectroscopy (EDX). The results revealed that the Ni/ZnO–SnO2 material consists of aggregated cassiterite SnO2 and wurtzite ZnO nanoparticles (NPs) with a size ranging from 14 to 40 nm. Furthermore, they show that Ni adding induces a dominant effect on the optical, structural and morphological properties of ZnO–SnO2 NPs. The photocatalytic behavior of the synthesized nanocomposites is investigated using rhodamine B (RhB) as model organic pollutant. A maximum degradation efficiency of 96% is achieved under visible light irradiation. While nickel doping did not enhance the photocatalytic activity of ZnO–SnO2 NPs, the photocatalytic performance of Ni/ZnO–SnO2 NPs is much higher than that of Ni-doped ZnO NPs. The photodegradation mechanism is believed to occur through photosensitization.

Structural characterization and properties of nanocrystalline Sn1−xCoxO2 based dilute magnetic semiconductors

Abstract

Synthesis of TiO2(B)/SnO2 composite materials as an anode for lithium-ion batteries

A TiO2(B) nanosheets/SnO2 nanoparticles composite was prepared by the hydrothermal and chemical bath deposition (CBD) methods, and its electrochemical properties were investigated for use as the anode material of a lithium-ion battery. The as-prepared composites consisted of monoclinic-phase TiO2(B) nanosheets and cassiterite structure SnO2 nanoparticles, in which SnO2 nanoparticles were uniformly decorated on the TiO2(B) nanosheets. The TiO2(B)/SnO2 composites showed a higher reversible capacity and better durability than that of the pure TiO2(B) for use as a battery anode. The composite electrodes exhibiting a high initial discharge capacity of 2239.1mAhg−1 and a discharge capacity of more than 868.7mAhg−1 could be maintained after 50 cycles at 0.1C in a voltage range of 1.0–3.0V at room temperature. The results suggest that TiO2(B) nanosheets coated with SnO2 could be suitable for use as a stable anode material for lithium-ion batteries. In addition, the coulombic efficiency of the nanosheets remains at an average of 93.1% for the 3rd–50th cycles.

Preparation and Characterization of Cassiterite (Sno2) and Its Application in the Hydrogenation of Methyl Esters

Tin oxide (IV) or cassiterite obtained by the controlled precipitation method was characterized by different physical and chemical techniques such as TEM, surface area, XRD and RTP for the determination of the morphology, particle size distribution and reduction temperature of the system and then, a pure catalyst and doped with tin (Sn) and nickel (Ni) is employed in the hydrogenation of methyl esters from palm oil. Monitoring the reaction was carried out by gas chromatography and it was found that the Sn-doped system showed a higher activity towards hydrogenation. The products obtained during and after the reaction were analyzed by FT-IR. We found that the hydrogenation of double bonds of the carbon chain was the main reaction, but there were also products resulting from isomerization and surprisingly a small fraction of fatty alcohols with tin-based catalyst Sn/SnO2.