Morphology-modulation of SnO2 Hierarchical Architectures by Zn Doping for Glycol Gas Sensing and Photocatalytic Applications

NASA Astrophysics Data System (ADS)

Zhao, Qinqin; Ju, Dianxing; Deng, Xiaolong; Huang, Jinzhao; Cao, Bingqiang; Xu, Xijin

2015-01-01

The morphology of SnO2 nanospheres was transformed into ultrathin nanosheets assembled architectures after Zn doping by one-step hydrothermal route. The as-prepared samples were characterized in detail by various analytical techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen adsorption-desorption technique. The Zn-doped SnO2 nanostructures proved to be the efficient gas sensing materials for a series of flammable and explosive gases detection, and photocatalysts for the degradation of methyl orange (MO) under UV irradiation. It was observed that both of the undoped and Zn-doped SnO2 after calcination exhibited tremendous gas sensing performance toward glycol. The response (S = Ra/Rg) of Zn-doped SnO2 can reach to 90 when the glycol concentration is 100 ppm, which is about 2 times and 3 times higher than that of undoped SnO2 sensor with and without calcinations, respectively. The result of photocatalytic activities demonstrated that MO dye was almost completely degraded (~92%) by Zn-doped SnO2 in 150 min, which is higher than that of others (MO without photocatalyst was 23%, undoped SnO2 without and with calcination were 55% and 75%, respectively).

Morphology-modulation of SnO2 Hierarchical Architectures by Zn Doping for Glycol Gas Sensing and Photocatalytic Applications

PubMed Central

Zhao, Qinqin; Ju, Dianxing; Deng, Xiaolong; Huang, Jinzhao; Cao, Bingqiang; Xu, Xijin

2015-01-01

The morphology of SnO2 nanospheres was transformed into ultrathin nanosheets assembled architectures after Zn doping by one-step hydrothermal route. The as-prepared samples were characterized in detail by various analytical techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen adsorption-desorption technique. The Zn-doped SnO2 nanostructures proved to be the efficient gas sensing materials for a series of flammable and explosive gases detection, and photocatalysts for the degradation of methyl orange (MO) under UV irradiation. It was observed that both of the undoped and Zn-doped SnO2 after calcination exhibited tremendous gas sensing performance toward glycol. The response (S = Ra/Rg) of Zn-doped SnO2 can reach to 90 when the glycol concentration is 100 ppm, which is about 2 times and 3 times higher than that of undoped SnO2 sensor with and without calcinations, respectively. The result of photocatalytic activities demonstrated that MO dye was almost completely degraded (~92%) by Zn-doped SnO2 in 150 min, which is higher than that of others (MO without photocatalyst was 23%, undoped SnO2 without and with calcination were 55% and 75%, respectively). PMID:25597269

Comparison of Photocatalytic Performance of Different Types of Graphene in Fe3O4/SnO2 Composites

NASA Astrophysics Data System (ADS)

Paramarta, Valentinus; Taufik, Ardiansyah; Saleh, Rosari

2017-03-01

We have reported the role of annealing temperature Fe3O4/SnO2 nanocomposites as a photocatalyst for remove methylene blue (MB) dye from aqueous solution. However, how to enhanced the degradation performance of Fe3O4/SnO2 nanocomposites is important to its photocatalytic application. Therefore, in this work Fe3O4/SnO2 nanocomposites was combined with two different types of graphene materials (NGP and grahene) to improve the photocatalytic performance for remove methylene blue (MB) dye. Fe3O4/SnO2/NGP and Fe3O4/SnO2/graphene have been successfully synthesized by co-precipitation method. The influence of two types graphene on Fe3O4/SnO2 nanocomposites properties were systematically investigated by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Thermal gravimetric analysis (TGA). Degradation of methylene Blue (MB) in aqueous solution was studied in detail under photocatalytic process. Effect of catalyst dosage (0.1-0.4 g/L) and scavengers on dye degradation were carried out to check the efficiency of photocatalyst. The results indicated Fe3O4/SnO2/graphene displayed higher photocatalytic activity than other catalyst. The reusability tests have also been done to ensure the stability of the used photocatalyst.

Synthesis and enhanced acetone gas-sensing performance of ZnSnO3/SnO2 hollow urchin nanostructures

NASA Astrophysics Data System (ADS)

Lian, Dandan; Shi, Bing; Dai, Rongrong; Jia, Xiaohua; Wu, Xiangyang

2017-12-01

A kind of novel ZnSnO3/SnO2 hollow urchin nanostructure was synthesized by a facile, eco-friendly two-step liquid-phase process. The structure, morphology, and composition of samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption techniques. The results revealed that many tiny needle-like SnO2 nanowires with the average diameter of 5 nm uniformly grew on the surface of the ZnSnO3 hollow microspheres and the ZnSnO3/SnO2 hollow urchin nanostructures with different SnO2 content also were successfully prepared. In order to comprehend the evolution process of the ZnSnO3/SnO2 hollow urchin nanostructures, the possible growth mechanism of samples was illustrated via several experiments in different reaction conditions. Moreover, the gas-sensing performance of as-prepared samples was investigated. The results showed that ZnSnO3/SnO2 hollow urchin nanostructures with high response to various concentration levels of acetone enhanced selectivity, satisfying repeatability, and good long-term stability for acetone detection. Specially, the 10 wt% ZnSnO3/SnO2 hollow urchin nanostructure exhibited the best gas sensitivity (17.03 for 50 ppm acetone) may be a reliable biomarker for the diabetes patients, which could be ascribed to its large specific surface area, complete pore permeability, and increase of chemisorbed oxygen due to the doping of SnO2.

Preparation and characterization of SnO2 and Carbon Co-coated LiFePO4 cathode materials.

PubMed

Wang, Haibin; Liu, Shuxin; Huang, Yongmao

2014-04-01

The SnO2 and carbon co-coated LiFePO4 cathode materials were successfully synthesized by solid state method. The microstructure and morphology of LiFePO4 composites were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscope. The results showed that the SnO2 and carbon co-coated LiFePO4 cathode materials exhibited more uniform particle size distribution. Compared with the uncoated LiFePO4/C, the structure of LiFePO4 with SnO2 and carbon coating had no change. The existence of SnO2 and carbon coating layer effectively enhanced the initial discharge capacity. Among the investigated samples, the one with DBTDL:LiFePO4 molar ratios of 7:100 exhibited the best electrochemical performance.

In situ studies of ion irradiated inverse spinel compound magnesium stannate (Mg 2SnO 4)

NASA Astrophysics Data System (ADS)

Xu, P.; Tang, M.; Nino, J. C.

2009-06-01

Magnesium stannate spinel (Mg 2SnO 4) was synthesized through conventional solid state processing and then irradiated with 1.0 MeV Kr 2+ ions at low temperatures 50 and 150 K. Structural evolutions during irradiation were monitored and recorded through bright field images and selected-area electron diffraction patterns using in situ transmission electron microscopy. The amorphization of Mg 2SnO 4 was achieved at an ion dose of 5 × 10 19 Kr ions/m 2 at 50 K and 10 20 Kr ions/m 2 at 150 K, which is equivalent to an atomic displacement damage of 5.5 and 11.0 dpa, respectively. The spinel crystal structure was thermally recovered at room temperature from the amorphous phase caused by irradiation at 50 K. The calculated electronic and nuclear stopping powers suggest that the radiation damage caused by 1 MeV Kr 2+ ions in Mg 2SnO 4 is mainly due to atomic displacement induced defect accumulation. The radiation tolerance of Mg 2SnO 4 was finally compared with normal spinel MgAl 2O 4.

Effects of SnO2, WO3, and ZrO2 addition on the magnetic and mechanical properties of NiCuZn ferrites

NASA Astrophysics Data System (ADS)

Wang, Sea-Fue; Yang, Hsiao-Ching; Hsu, Yung-Fu; Hsieh, Chung-Kai

2015-01-01

In this study, the effects of SnO2, WO3 and ZrO2 addition at levels up to 5 wt% on the magnetic and mechanical properties of Ni0.5Cu0.3Zn0.2Fe2O4 ceramics were investigated. Only Ni0.5Cu0.3Zn0.2Fe2O4 ceramic with a SnO2 addition of ≥3.5 wt% required a densification temperature of 1150 °C, while the others reached maximum densification at 1075 °C. All samples revealed a pure spinel phase and a uniform microstructure, except for the Ni0.5Cu0.3Zn0.2Fe2O4 ceramic with the WO3 addition, which showed an exaggerated grain growth accompanied with a small amount of needle-shaped Cu0.85Zn0.15WO4 second phase. The fracture mode in the pure Ni0.5Cu0.3Zn0.2Fe2O4 ceramic revealed a transgranular phase, as the CuO second phase increased the grain boundary strength; the Ni0.5Cu0.3Zn0.2Fe2O4 ceramics sintered with 5 wt% additives showed an intergranular phase. The Vickers hardness and the bending strength of the Ni0.5Cu0.3Zn0.2Fe2O4 ceramic were 733.6 and 62.0 MPa, respectively. The Vickers hardness of the ferrite with added SnO2 or ZrO2 showed only a slight improvement, while an apparent change (832.7) was observed with the addition of 5.0 wt% WO3. The bending strength of the ferrite was optimized at 75.7 MPa with 2.0 wt% SnO2 and at 90.5 MPa with 3.5 wt% ZrO2, while that of the ferrite sintered with WO3 added dropped gradually from 62.0 to 47.7 MPa as the amount of WO3 was increased from 0 to 5.0 wt% due to the non-uniform microstructure. The pure Ni0.5Cu0.3Zn0.2Fe2O4 ceramic sintered at 1075 °C had an initial permeability of 356.9 and a quality factor of 71.2. The addition of ZrO2 led to a significant increase in the initial permeability (588.4 at 5.0 wt% ZrO2), but a slight decline in the quality factor (56.6 at 5.0 wt% ZrO2).

Neutron diffraction study of the inverse spinels Co2TiO4 and Co2SnO4

NASA Astrophysics Data System (ADS)

Thota, S.; Reehuis, M.; Maljuk, A.; Hoser, A.; Hoffmann, J.-U.; Weise, B.; Waske, A.; Krautz, M.; Joshi, D. C.; Nayak, S.; Ghosh, S.; Suresh, P.; Dasari, K.; Wurmehl, S.; Prokhnenko, O.; Büchner, B.

2017-10-01

We report a detailed single-crystal and powder neutron diffraction study of Co2TiO4 and Co2SnO4 between the temperature 1.6 and 80 K to probe the spin structure in the ground state. For both compounds the strongest magnetic intensity was observed for the (111)M reflection due to ferrimagnetic ordering, which sets in below TN=48.6 and 41 K for Co2TiO4 and Co2SnO4 , respectively. An additional low intensity magnetic reflection (200)M was noticed in Co2TiO4 due to the presence of an additional weak antiferromagnetic component. Interestingly, from both the powder and single-crystal neutron data of Co2TiO4 , we noticed a significant broadening of the magnetic (111)M reflection, which possibly results from the disordered character of the Ti and Co atoms on the B site. Practically, the same peak broadening was found for the neutron powder data of Co2SnO4 . On the other hand, from our single-crystal neutron diffraction data of Co2TiO4 , we found a spontaneous increase of particular nuclear Bragg reflections below the magnetic ordering temperature. Our data analysis showed that this unusual effect can be ascribed to the presence of anisotropic extinction, which is associated to a change of the mosaicity of the crystal. In this case, it can be expected that competing Jahn-Teller effects acting along different crystallographic axes can induce anisotropic local strain. In fact, for both ions Ti3 + and Co3 +, the 2 tg levels split into a lower dx y level yielding a higher twofold degenerate dx z/dy z level. As a consequence, one can expect a tetragonal distortion in Co2TiO4 with c /a <1 , which we could not significantly detect in the present work.

Bouquet-Like Mn2SnO4 Nanocomposite Engineered with Graphene Sheets as an Advanced Lithium-Ion Battery Anode.

PubMed

Rehman, Wasif Ur; Xu, Youlong; Sun, Xiaofei; Ullah, Inam; Zhang, Yuan; Li, Long

2018-05-30

Volume expansion is a major challenge associated with tin oxide (SnO x ), which causes poor cyclability in lithium-ion battery anode. Bare tin dioxide (SnO 2 ), tin dioxide with graphene sheets (SnO 2 @GS), and bouquet-like nanocomposite structure (Mn 2 SnO 4 @GS) are prepared via hydrothermal method followed by annealing. The obtained composite material presents a bouquet structure containing manganese and tin oxide nanoparticle network with graphene sheets. Benefiting from this porous nanostructure, in which graphene sheets provide high electronic pathways to enhance the electronic conductivity, uniformly distributed particles offer accelerated kinetic reaction with lithium ion and reduced volume deviation in the tin dioxide (SnO 2 ) particle during charge-discharge testing. As a consequence, ternary composite Mn 2 SnO 4 @GS showed a high rate performance and outstanding cyclability of anode material for lithium-ion batteries. The electrode achieved a specific capacity of about 1070 mA h g -1 at a current density of 400 mA g -1 after 200 cycles; meanwhile, the electrode still delivered a specific capacity of about 455 mA h g -1 at a high current density of 2500 mA g -1 . Ternary Mn 2 SnO 4 @GS material could facilitate fabrication of unique structure and conductive network as advanced lithium-ion battery.

Interfacial effect on the structural and optical properties of pure SnO2 and dual shells (ZnO; SiO2) coated SnO2 core-shell nanospheres for optoelectronic applications

NASA Astrophysics Data System (ADS)

Selvi, N.; Sankar, S.; Dinakaran, K.

2014-12-01

Nanocrystallites of SnO2 core and dual shells (ZnO, SiO2) coated SnO2 core-shell nanospheres were successfully synthesized by co-precipitation method. The as prepared and annealed samples were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), High resolution transmission electron microscopy (HRTEM) and UV-Vis analysis. XRD pattern confirms the obtained SnO2 core with tetragonal rutile crystalline structure and the shell ZnO with hexagonal structure. FTIR result shows the functional groups present in the samples. The spherical morphology and the formation of the core-shell structures have been confirmed by HRTEM measurements. The UV-Vis showed that band gap is red shifted for as-prepared and the shells coated core-shell samples. From this investigation it can be concluded that the surface modification with different metal and insulating oxides strongly influences the optical properties of the core-shell materials which enhance their potential applications towards optical devices fabrication.

One-Pot Green Synthesis of Ag-Decorated SnO2 Microsphere: an Efficient and Reusable Catalyst for Reduction of 4-Nitrophenol.

PubMed

Hu, Min; Zhang, Zhenwei; Luo, Chenkun; Qiao, Xiuqing

2017-12-01

In this paper, hierarchical Ag-decorated SnO 2 microspheres were synthesized by a facile one-pot hydrothermal method. The resulting composites were characterized by XRD, SEM, TEM, XPS, BET, and FTIR analysis. The catalytic performances of the samples were evaluated with the reduction of 4-nitrophenol to 4-aminophenol by potassium borohydride (KBH 4 ) as a model reaction. Time-dependent experiments indicated that the hierarchical microspheres assembled from SnO 2 and Ag nanoparticles can be formed when the react time is less than 10 h. With the increase of hydrothermal time, SnO 2 nanoparticles will self-assemble into SnO 2 nanosheets and Ag nanoparticles decorated SnO 2 nanosheets were obtained. When evaluated as catalyst, the obtained Ag-decorated SnO 2 microsphere prepared for 36 h exhibited excellent catalytic performance with normalized rate constant (κ nor ) of 6.20 min -1 g -1 L, which is much better than that of some previous reported catalysts. Moreover, this Ag-decorated SnO 2 microsphere demonstrates good reusability after the first five cycles. In addition, we speculate the formation mechanism of the hierarchical Ag-decorated SnO 2 microsphere and discussed the possible origin of the excellent catalytic activity.

Calcination Method Synthesis of SnO2/g-C3N4 Composites for a High-Performance Ethanol Gas Sensing Application

PubMed Central

Cao, Jianliang; Qin, Cong; Wang, Yan; Zhang, Bo; Gong, Yuxiao; Zhang, Huoli; Sun, Guang; Bala, Hari; Zhang, Zhanying

2017-01-01

The SnO2/g-C3N4 composites were synthesized via a facile calcination method by using SnCl4·5H2O and urea as the precursor. The structure and morphology of the as-synthesized composites were characterized by the techniques of X-ray diffraction (XRD), the field-emission scanning electron microscopy and transmission electron microscopy (SEM and TEM), energy dispersive spectrometry (EDS), thermal gravity and differential thermal analysis (TG-DTA), and N2-sorption. The analysis results indicated that the as-synthesized samples possess the two dimensional structure. Additionally, the SnO2 nanoparticles were highly dispersed on the surface of the g-C3N4nanosheets. The gas-sensing performance of the as-synthesized composites for different gases was tested. Moreover, the composite with 7 wt % g-C3N4 content (SnO2/g-C3N4-7) SnO2/g-C3N4-7 exhibits an admirable gas-sensing property to ethanol, which possesses a higher response and better selectivity than that of the pure SnO2-based sensor. The high surface area of the SnO2/g-C3N4 composite and the good electronic characteristics of the two dimensional graphitic carbon nitride are in favor of the elevated gas-sensing property. PMID:28468245

Evaluation of SnO2 for sunlight photocatalytic decontamination of water.

PubMed

Aslam, M; Qamar, M Tariq; Ali, Shahid; Rehman, Ateeq Ur; Soomro, M T; Ahmed, Ikram; Ismail, I M I; Hameed, A

2018-07-01

The broad bandgap tin (IV) oxide (SnO 2 ) is the least investigated semiconductor material for photocatalytic water decontamination in sunlight exposure. A detailed study covering the synthesis, characterization and the evaluation of photocatalytic activity of SnO 2 , in the natural sunlight exposure, is presented. The structural characterization by XRD revealed the formation of phase pure tetragonal SnO 2 with the average crystallite size of ∼41.5 nm whereas minor Sn 2+ states in the material were identified by XPS analysis. As explored by diffuse reflectance (DR) and photoluminescence (PL) spectroscopy, the material exhibited a distinct absorption edge at ∼3.4 eV. The morphological and microstructure analysis of the synthesized SnO 2 was carried out by FESEM and HRTEM. The electrochemical impedance spectroscopy (EIS) and chronopotentiometry (CP) predicted the better charge transport and retention ability of the material under illumination whereas the Mott-Schottky extrapolation prophesied the n-type behavior with the flat-band potential of -0.60 V. The photocatalytic activity of SnO 2 was assessed in the exposure of complete spectrum natural sunlight for the removal of 2,4,6-trichlorophenol. The HPLC and TOC analysis monitored the progress of degradation and mineralization whereas the released chloride ions were evaluated by ion chromatography. The effect of the transition metal ions (Fe 3+ , Cu 2+ , Ni 2+, and Zn 2+ ) as electron capture agents and H 2 O 2 as ROS generator was explored during the degradation process. The utility of the material for the simultaneous removal of chlorophenols in the mixture was also investigated. The SnO 2 exhibited sustained activity in the repeated use. Based on experimental evidence congregated, the mechanism of the removal process and the efficacy of SnO 2 for sunlight photocatalytic decontamination of water was established. Copyright © 2018 Elsevier Ltd. All rights reserved.

Novel microwave-assisted synthesis of porous g-C3N4/SnO2 nanocomposite for solar water-splitting

NASA Astrophysics Data System (ADS)

Seza, A.; Soleimani, F.; Naseri, N.; Soltaninejad, M.; Montazeri, S. M.; Sadrnezhaad, S. K.; Mohammadi, M. R.; Moghadam, H. Asgari; Forouzandeh, M.; Amin, M. H.

2018-05-01

Highly porous nanocomposites of graphitic-carbon nitride and tin oxide (g-C3N4/SnO2) were prepared through simple pyrolysis of urea molecules under microwave irradiation. The initial amount of tin was varied in order to investigate the effect of SnO2 content on preparation and properties of the composites. The synthesized nanocomposites were well-characterized by XRD, FE-SEM, HR-TEM, BET, FTIR, XPS, DRS, and PL. A homogeneous distribution of SnO2 nanoparticles with the size of less than 10 nm on the porous C3N4 sheets could be obtained, suggesting that in-situ synthesis of SnO2 nanoparticles was responsible for the formation of g-C3N4. The process likely occurred by the aid of the large amounts of OH groups formed on the surfaces of SnO2 nanoparticles during the polycondensation reactions of tin derivatives which could facilitate the pyrolysis of urea to carbon nitride. The porous nanocomposite prepared with initial tin amount of 0.175 g had high specific surface area of 195 m2 g-1 which showed high efficiency photoelectrochemical water-splitting ability. A maximum photocurrent density of 33 μA cm-2 was achieved at an applied potential of 0.5 V when testing this nanocomposite as photo-anode in water-splitting reactions under simulated visible light irradiation, introducing it as a promising visible light photoactive material.

Ultrasonic-assisted pyrolyzation fabrication of reduced SnO2–x /g-C3N4 heterojunctions: Enhance photoelectrochemical and photocatalytic activity under visible LED light irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Kai; Zeng, Xiaoqiao; Gao, Shanmin

Novel SnO 2–x/g-C 3N 4 heterojunction nanocomposites composed of reduced SnO 2–x nanoparticles and exfoliated g-C 3N 4 nanosheets were prepared by a convenient one-step pyrolysis method. The structural, morphological, and optical properties of the as-prepared nanocomposites were characterized in detail, indicating that the aggregation of g-C 3N 4 nanosheets was prevented by small, well-dispersed SnO 2–x nanoparticles. The ultraviolet–visible spectroscopy absorption bands of the nanocomposites were shifted to a longer wavelength region than those exhibited by pure SnO 2 or g-C 3N 4. The charge transfer and recombination processes occurring in the nanocomposites were investigated using linear scan voltammetrymore » and electrochemical impedance spectroscopy. Under 30-W visible-light-emitting diode irradiation, the heterojunction containing 27.4 wt.% SnO 2–x exhibited the highest photocurrent density of 0.0468 mA·cm–2, which is 33.43 and 5.64 times larger than that of pure SnO 2 and g-C 3N 4, respectively. The photocatalytic activity of the heterojunction material was investigated by degrading rhodamine B under irradiation from the same light source. Kinetic study revealed a promising degradation rate constant of 0.0226 min-1 for the heterojunction containing 27.4 wt.% SnO 2–x, which is 32.28 and 5.79 times higher than that of pure SnO 2 and g-C 3N 4, respectively. The enhanced photoelectrochemical and photocatalytic performances of the nanocomposite may be due to its appropriate SnO 2–x content and the compact structure of the junction between the SnO 2–x nanoparticles and the g-C 3N 4 nanosheets, which inhibits the recombination of photogenerated electrons and holes.« less

Cation vacancies and electrical compensation in Sb-doped thin-film SnO2 and ZnO

NASA Astrophysics Data System (ADS)

Korhonen, E.; Prozheeva, V.; Tuomisto, F.; Bierwagen, O.; Speck, J. S.; White, M. E.; Galazka, Z.; Liu, H.; Izyumskaya, N.; Avrutin, V.; Özgür, Ü.; Morkoç, H.

2015-02-01

We present positron annihilation results on Sb-doped SnO2 and ZnO thin films. The vacancy types and the effect of vacancies on the electrical properties of these intrinsically n-type transparent semiconducting oxides are studied. We find that in both materials low and moderate Sb-doping leads to formation of vacancy clusters of variable sizes. However, at high doping levels cation vacancy defects dominate the positron annihilation signal. These defects, when at sufficient concentrations, can efficiently compensate the n-type doping produced by Sb. This is the case in ZnO, but in SnO2 the concentrations appear too low to cause significant compensation.

SnoN Stabilizes the SMAD3/SMAD4 Protein Complex

PubMed Central

Walldén, Karin; Nyman, Tomas; Hällberg, B. Martin

2017-01-01

TGF-β signaling regulates cellular processes such as proliferation, differentiation and apoptosis through activation of SMAD transcription factors that are in turn modulated by members of the Ski-SnoN family. In this process, Ski has been shown to negatively modulate TGF-β signaling by disrupting active R-SMAD/Co-SMAD heteromers. Here, we show that the related regulator SnoN forms a stable complex with the R-SMAD (SMAD3) and the Co-SMAD (SMAD4). To rationalize this stabilization at the molecular level, we determined the crystal structure of a complex between the SAND domain of SnoN and the MH2-domain of SMAD4. This structure shows a binding mode that is compatible with simultaneous coordination of R-SMADs. Our results show that SnoN, and SMAD heteromers can form a joint structural core for the binding of other transcription modulators. The results are of fundamental importance for our understanding of the molecular mechanisms behind the modulation of TGF-β signaling. PMID:28397834

SnoN Stabilizes the SMAD3/SMAD4 Protein Complex.

PubMed

Walldén, Karin; Nyman, Tomas; Hällberg, B Martin

2017-04-11

TGF-β signaling regulates cellular processes such as proliferation, differentiation and apoptosis through activation of SMAD transcription factors that are in turn modulated by members of the Ski-SnoN family. In this process, Ski has been shown to negatively modulate TGF-β signaling by disrupting active R-SMAD/Co-SMAD heteromers. Here, we show that the related regulator SnoN forms a stable complex with the R-SMAD (SMAD3) and the Co-SMAD (SMAD4). To rationalize this stabilization at the molecular level, we determined the crystal structure of a complex between the SAND domain of SnoN and the MH2-domain of SMAD4. This structure shows a binding mode that is compatible with simultaneous coordination of R-SMADs. Our results show that SnoN, and SMAD heteromers can form a joint structural core for the binding of other transcription modulators. The results are of fundamental importance for our understanding of the molecular mechanisms behind the modulation of TGF-β signaling.

Hollow SnO2@Co3O4 core-shell spheres encapsulated in three-dimensional graphene foams for high performance supercapacitors and lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhao, Bo; Huang, Sheng-Yun; Wang, Tao; Zhang, Kai; Yuen, Matthew M. F.; Xu, Jian-Bin; Fu, Xian-Zhu; Sun, Rong; Wong, Ching-Ping

2015-12-01

Hollow SnO2@Co3O4 spheres are fabricated using 300 nm spherical SiO2 particles as template. Then three-dimensional graphene foams encapsulated hollow SnO2@Co3O4 spheres are successfully obtained through self-assembly in hydrothermal process from graphene oxide nanosheets and metal oxide hollow spheres. The three-dimensional graphene foams encapsulated architectures could greatly improve the capacity, cycling stability and rate capability of hollow SnO2@Co3O4 spheres electrodes due to the highly conductive networks and flexible buffering matrix. The three-dimensional graphene foams encapsulated hollow SnO2@Co3O4 spheres are promising electrode materials for supercapacitors and lithium-ion batteries.

Characterization of core/shell structures based on CdTe and GaAs nanocrystalline layers deposited on SnO2 microwires

NASA Astrophysics Data System (ADS)

Ghimpu, L.; Ursaki, V. V.; Pantazi, A.; Mesterca, R.; Brâncoveanu, O.; Shree, Sindu; Adelung, R.; Tiginyanu, I. M.; Enachescu, M.

2018-04-01

We report the fabrication and characterization of SnO2/CdTe and SnO2/GaAs core/shell microstructures. CdTe or GaAs shell layers were deposited by radio-frequency (RF) magnetron sputtering on core SnO2 microwires synthesized by a flame-based thermal oxidation method. The produced structures were characterized by scanning electron microscopy (SEM), high-resolution scanning transmission electron microscope (HR-STEM), X-ray diffraction (XRD), Raman scattering and FTIR spectroscopy. It was found that the SnO2 core is of the rutile type, while the shells are composed of CdTe or GaAs nanocrystallites of zincblende structure with the dimensions of crystallites in the range of 10-20 nm. The Raman scattering investigations demonstrated that the quality of the porous nanostructured shell is improved by annealing at temperatures of 420-450 °C. The prospects of implementing these microstructures in intrinsic type fiber optic sensors are discussed.

A study of structural, electrical, and optical properties of p-type Zn-doped SnO2 films versus deposition and annealing temperature

NASA Astrophysics Data System (ADS)

Le, Tran; Phuc Dang, Huu; Luc, Quang Ho; Hieu Le, Van

2017-04-01

This study presents a detailed investigation of the structural, electrical, and optical properties of p-type Zn-doped SnO2 versus the deposition and annealing temperature. Using a direct-current (DC) magnetron sputtering method, p-type transparent conductive Zn-doped SnO2 (ZTO) films were deposited on quartz glass substrates. Zn dopants incorporated into the SnO2 host lattice formed the preferred dominant SnO2 (1 0 1) and (2 1 1) planes. X-ray photoelectron spectroscopy (XPS) was used for identifying the valence state of Zn in the ZTO film. The electrical property of ZTO films changed from n-type to p-type at the threshold temperature of 400 °C, and the films achieved extremely high conductivity at the optimum annealing temperature of 600 °C after annealing for 2 h. The best conductive property of the film was obtained on a 10 wt% ZnO-doped SnO2 target with a resistivity, hole concentration, and hole mobility of 0.22 Ω · cm, 7.19  ×  1018 cm-3, and 3.95 cm2 V-1 s-1, respectively. Besides, the average transmission of films was  >84%. The surface morphology of films was examined using scanning electron microscopy (SEM). Moreover, the acceptor level of Zn2+ was identified using photoluminescence spectra at room temperature. Current-voltage (I-V) characteristics revealed the behavior of a p-ZTO/n-Si heterojunction diode.

Chemical and thermal stability of the characteristics of filtered vacuum arc deposited ZnO, SnO2 and zinc stannate thin films

NASA Astrophysics Data System (ADS)

Çetinörgü, E.; Goldsmith, S.

2007-09-01

ZnO, SnO2 and zinc stannate thin films were deposited on commercial microscope glass and UV fused silica substrates using filtered vacuum arc deposition system. During the deposition, the substrate temperature was at room temperature (RT) or at 400 °C. The film structure and composition were determined using x-ray diffraction and x-ray photoelectron spectroscopy, respectively. The transmission of the films in the VIS was 85% to 90%. The thermal stability of the film electrical resistance was determined in air as a function of the temperature in the range 28 °C (RT) to 200 °C. The resistance of ZnO increased from ~ 5000 to 105 Ω when heated to 200 °C, that of SnO2 films increased from 500 to 3900 Ω, whereas that of zinc stannate thin films increased only from 370 to 470 Ω. During sample cooling to RT, the resistance of ZnO and SnO2 thin films continued to rise considerably; however, the increase in the zinc stannate thin film resistance was significantly lower. After cooling to RT, ZnO and SnO2 thin films became practically insulators, while the resistance of zinc stannate was 680 Ω. The chemical stability of the films was determined by immersing in acidic and basic solutions up to 27 h. The SnO2 thin films were more stable in the HCl solution than the ZnO and the zinc stannate thin films; however, SnO2 and zinc stannate thin films that were immersed in the NaOH solution did not dissolve after 27 h.

A simple structure of Cu2ZnSnS4/CdS solar cells prepared by sputtering

NASA Astrophysics Data System (ADS)

Li, Zhishan; Wang, Shurong; Ma, Xun; Yang, Min; Jiang, Zhi; Liu, Tao; Lu, Yilei; Liu, Sijia

2017-12-01

In this work, Cu2ZnSnS4 (CZTS) thin films were grown on Mo-coated Soda-lime-glass (SLG) substrates by annealing of sputtered ZnS/Sn/CuS precursors at 580 ℃ for 15 min. As a try, the CZTS solar cells were fabricated using simple structure of Mo-coated SLG/CZTS/CdS/Al and traditional structure of Mo-coated SLG/CZTS/CdS/i-ZnO/In2O3:SnO2 (ITO)/Al, respectively. The results show that the CZTS device with simple structure can achieve same level of the open circuit voltage (Voc) compared with that of traditional structure. In addition, the power conversion efficiency of 2.95% and 3.59% were obtained with simple structure and traditional structure, respectively. The CZTS solar cell with simple structure provides a promising way and an easy process to prepare high-performance CZTS thin film solar cells which is available to large-scale industrial production in the future.

Enhanced photovoltaic performance of dye sensitized solar cell using SnO2 nanoflowers

NASA Astrophysics Data System (ADS)

Arote, Sandeep A.; Tabhane, Vilas A.; Pathan, Habib M.

2018-01-01

The study highlighted enhanced performance of SnO2 based DSSC using photoanode with nanostructured morphology. The simple organic surfactant free hydrothermal synthesis method was used for preparation of SnO2 nanoflowers for dye sensitized solar cell (DSSC) application. The hydrothermal reaction time was varied to obtain different SnO2 nanostructures. The hydrothermal reaction time showed considerable effect on optical and structural properties of the prepared samples. The results indicated that the prepared samples were pure rutile SnO2. The band gap of prepared samples was greater than bulk SnO2 and varied from 3.64 to 3.81 eV with increase in hydrothermal reaction time. With increase in reaction time from 4 to 24 h, the microstructure of SnO2 changed from agglomerated nanoparticles to nanopetals and finally to self-assembled nanoflowers. Flower-like SnO2 nanostructures showed size around 300-700 nm, and composed of large numbers of 3 dimensional petals connected with each other forming 3D nanoflowers by self-assembly. Consequently, the DSSC with flower-like SnO2 nanostructures exhibited good photovoltaic performance with Voc, Jsc and η about 0.43 V, 4.36 mA/cm2 and 1.11%, respectively.

SnO 2 nanowires decorated with forsythia-like TiO 2 for photoenergy conversion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Ik Jae; Park, Sangbaek; Kim, Dong Hoe

Here, we report forsythia-like TiO 2-decorated SnO 2 nanowires on fluorine-doped SnO 2 electrode as a photoelectrode of dye-sensitized solar cells. When SnO 2 nanowires grown via vapor-liquid-solid reaction were soaked in TiCl 4 solution, leaf-shaped rutile TiO 2 was grown onto the surface of the nanowires. The TiO 2 decoration increases the short circuit current (J sc), open circuit voltage (V oc) and fill factor (FF) of dye-sensitized solar cells. Further, electron lifetime increased by employing an atomic-layer-deposited TiO 2 nanoshell between the TiO 2 leaves and the SnO 2 nanowire, due to preventing charge recombination at the nanowire/electrolytemore » interface.« less

SnO 2 nanowires decorated with forsythia-like TiO 2 for photoenergy conversion

DOE PAGES

Park, Ik Jae; Park, Sangbaek; Kim, Dong Hoe; ...

2017-05-17

Here, we report forsythia-like TiO 2-decorated SnO 2 nanowires on fluorine-doped SnO 2 electrode as a photoelectrode of dye-sensitized solar cells. When SnO 2 nanowires grown via vapor-liquid-solid reaction were soaked in TiCl 4 solution, leaf-shaped rutile TiO 2 was grown onto the surface of the nanowires. The TiO 2 decoration increases the short circuit current (J sc), open circuit voltage (V oc) and fill factor (FF) of dye-sensitized solar cells. Further, electron lifetime increased by employing an atomic-layer-deposited TiO 2 nanoshell between the TiO 2 leaves and the SnO 2 nanowire, due to preventing charge recombination at the nanowire/electrolytemore » interface.« less

Fabrication and characterization of SnO2/ZnO gas sensors for detecting toluene gas.

PubMed

Min, Byung-Sam; Park, Young-Ho; Lee, Chang-Seop

2014-11-01

This study investigates the use of SnO2, ZnO, Ag, Au, Cu, In, Pd, Ru and carbon black to improve the sensitivity of a gas sensor for detecting toluene gas. Metal-SnO2/ZnO thick films were screen-printed onto Al2O3 substrates with platinum electrodes. The physico-chemical properties of the sensor materials were characterized using SEM/EDS, XRD, and BET analyses. Measuring the electrical resistance of each sensor as a function of the gas concentration determined the sensing characteristics. The sensors were tested using toluene, benzene, xylene, ethanol, methanol, ammonia and trimethylamine vapors with concentrations of 1-2000 ppm. The gas sensing properties of metal-SnO2/ZnO thick films depended on the content and variety of metals and the content of carbon black. The optimum condition of sensor material for toluene gas detection is operation temperature 300 degrees C and when metal catalyst Cu and carbon black were added. The best sensitivity and selectivity for toluene gas at 300 degrees C resulted from doping with 5 wt.% carbon black, 1 wt.% Cu and 20 wt.% ZnO to SnO2.

Nano SnO 2-Al 2O 3 mixed oxide and SnO 2-Al 2O 3-carbon composite oxides as new and novel electrodes for supercapacitor applications

NASA Astrophysics Data System (ADS)

Jayalakshmi, M.; Venugopal, N.; Raja, K. Phani; Rao, M. Mohan

New nano-materials like SnO 2-Al 2O 3 and SnO 2-Al 2O 3-carbon were synthesized by a single step hydrothermal method in searching for novel mixed oxides with high electrochemical double layer capacitance. A SnO 2-Al 2O 3-carbon sample was calcined at 600 °C and tested for its performance. The source of carbon was tetrapropyl ammonium hydroxide. The capacitive behavior of SnO 2 was compared to the performance of SnO 2-Al 2O 3, SnO 2-Al 2O 3-carbon and calcined SnO 2-Al 2O 3-carbon using the techniques of cyclic voltammetry, double potential step, chronopotentiometry and E-log I polarization. In 0.1 M NaCl solutions, SnO 2-Al 2O 3 gave the best performance with a value of 119 Fg -1 and cycled 1000 times. The nano-material mixed oxides were characterized by TEM, XRD, ICP-AES and SEM-EDAX.

Screen-printed SnO2/CNT quasi-solid-state gel-electrolyte supercapacitor

NASA Astrophysics Data System (ADS)

Kuok, Fei-Hong; Liao, Chen-Yu; Chen, Chieh-Wen; Hao, Yu-Chuan; Yu, Ing-Song; Chen, Jian-Zhang

2017-11-01

This study investigates a quasi-solid-state gel-electrolyte supercapacitor fabricated with nanoporous SnO2/CNT nanocomposite electrodes and a polyvinyl alcohol/sulfuric acid (PVA/H2SO4) gel electrolyte. First, pastes containing SnO2 nanoparticles, CNTs, ethyl cellulose, and terpineol are screen-printed onto carbon cloth. A tube furnace is then used for calcining the SnO2/CNT electrodes on carbon cloth. After furnace-calcination, the wettability of SnO2/CNT significantly improved; furthermore, the XPS analysis shows that number of C-O bond and oxygen content significantly decrease after furnace-calcination owing to the burnout of the ethyl cellulose by the furnace calcination processes. The furnace-calcined SnO2/CNT electrodes sandwich the PVA/H2SO4 gel electrolyte to form a supercapacitor. The fabricated supercapacitor exhibits an areal capacitance of 5.61 mF cm-2 when flat and 5.68 mF cm-2 under bending with a bending radius (R) of 1.0 cm. After a 1000 cycle stability test, the capacitance retention rates of the supercapacitor are 96% and 97% when flat and under bending (R  =  1.0 cm), respectively.

Time-Resolved Optical Emission Spectroscopy Diagnosis of CO2 Laser-Produced SnO2 Plasma

NASA Astrophysics Data System (ADS)

Lan, Hui; Wang, Xinbing; Zuo, Duluo

2016-09-01

The spectral emission and plasma parameters of SnO2 plasmas have been investigated. A planar ceramic SnO2 target was irradiated by a CO2 laser with a full width at half maximum of 80 ns. The temporal behavior of the specific emission lines from the SnO2 plasma was characterized. The intensities of Sn I and Sn II lines first increased, and then decreased with the delay time. The results also showed a faster decay of Sn I atoms than that of Sn II ionic species. The temporal evolutions of the SnO2 plasma parameters (electron temperature and density) were deduced. The measured temperature and density of SnO2 plasma are 4.38 eV to 0.5 eV and 11.38×1017 cm-3 to 1.1×1017 cm-3, for delay times between 0.1 μs and 2.2 μs. We also investigated the effect of the laser pulse energy on SnO2 plasma. supported by National Natural Science Foundation of China (No. 11304235) and the Director Fund of WNLO

Ternary composite of TiO2 nanotubes/Ti plates modified by g-C3N4 and SnO2 with enhanced photocatalytic activity for enhancing antibacterial and photocatalytic activity.

PubMed

Faraji, Masoud; Mohaghegh, Neda; Abedini, Amir

2018-01-01

A series of g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plates were fabricated via simple dipping of TiO 2 nanotubes/Ti in a solution containing SnCl 2 and g-C 3 N 4 nanosheets and finally annealing of the plates. Synthesized plates were characterized by various techniques. The SEM analysis revealed that the g-C 3 N 4 -SnO 2 nanosheets with high physical stability have been successfully deposited onto the surface of TiO 2 nanotubes/Ti plate. Photocatalytic activity was investigated using two probe chemical reactions: oxidative decomposition of acetic acid and oxidation of 2-propanol under irradiation. Antibacterial activities for Escherichia coli (E. coli) bacteria were also investigated in dark and under UV/Vis illuminations. Detailed characterization and results of photocatalytic and antibacterial activity tests revealed that semiconductor coupling significantly affected the photocatalyst properties synthesized and hence their photocatalytic and antibacterial activities. Modification of TiO 2 nanotubes/Ti plates with g-C 3 N 4 -SnO 2 deposits resulted in enhanced photocatalytic activities in both chemical and microbial systems. The g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plate exhibited the highest photocatalytic and antibacterial activity, probably due to the heterojunction between g-C 3 N 4 -SnO 2 and TiO 2 nanotubes/Ti in the ternary composite plate and thus lower electron/hole recombination rate. Based on the obtained results, a photocatalytic and an antibacterial mechanism for the degradation of E. coli bacteria and chemical pollutants over g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plate were proposed and discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of substrates on structural and optical properties of tin oxide (SnO2) nanostructures.

PubMed

Johari, Anima; Bhatnagar, M C; Rana, Vikas

2012-10-01

We report on controlling the morphology of tin oxide (SnO2) nanostructures and the study of the effect of surface morphology on structural and optical properties of SnO2 nanostuctures. In present work, Tin oxide (SnO2) nanostructures such as nanowires and nanorods have been grown by thermal evaporation of SnO2 powder. To demonstrate the effect of different substrates on the morphology of grown SnO2 nanostructures, the thermal evaporation of SnO2 powder was carried out on Si and gold catalyzed Si (Au/Si) substrates. The scanning-electron-microscopic analysis shows the growth of SnO2 nanowires on Au/Si substrate and growth of SnO2 nanorods on Si substrate. The scanning-and transmission-electron-microscopic analysis shows that the diameter of SnO2 nanowires and nanorods are about 70 nm and 95 nm respectively and their length is about 80 microm and 30 microm respectively. The vapor-liquid-solid (VLS) growth of SnO2 nanowires and vapor-solid (VS) growth of SnO2 nanorods is also confirmed with the help of TEM and EDX spectra. The synthesized SnO2 nanowires show tetragonal rutile structure of SnO2, whereas SnO2 nanorods show tetragonal rutile as well as cassiterite structure of SnO2. UV-Vis absorption spectra showed the optical band gaps of 4.1 eV and 3.8 eV for the SnO2 nanowires and the nanorods, respectively. The SnO2 nanowires and nanorods show photoluminescence with broad emission peaks centred at around 600 nm and 580 nm respectively. Raman spectra of SnO2 nanowires shows three Raman shifts (478, 632, 773 cm(-1)) corresponding to Eg, A1g and B2g vibration modes, whereas in Raman spectra of SnO2 nanorods, A1g peak is dramatically reduced and the B2g mode is totally quenched.

2D SnO2 Nanosheets: Synthesis, Characterization, Structures, and Excellent Sensing Performance to Ethylene Glycol

PubMed Central

Wan, Wenjin; Li, Yuehua; Ren, Xingping; Zhao, Yinping; Gao, Fan; Zhao, Heyun

2018-01-01

Two dimensional (2D)SnO2 nanosheets were synthesized by a substrate-free hydrothermal route using sodium stannate and sodium hydroxide in a mixed solvent of absolute ethanol and deionized water at a lower temperature of 130 °C. The characterization results of the morphology, microstructure, and surface properties of the as-prepared products demonstrated that SnO2 nanosheets with a tetragonal rutile structure, were composed of oriented SnO2 nanoparticles with a diameter of 6–12 nm. The X-ray diffraction (XRD) and high-resolution transmission electron microscope (FETEM) results demonstrated that the dominant exposed surface of the SnO2 nanoparticles was (101), but not (110). The growth and formation was supposed to follow the oriented attachment mechanism. The SnO2 nanosheets exhibited an excellent sensing response toward ethylene glycol at a lower optimal operating voltage of 3.4 V. The response to 400 ppm ethylene glycol reaches 395 at 3.4 V. Even under the low concentration of 5, 10, and 20 ppm, the sensor exhibited a high response of 6.9, 7.8, and 12.0 to ethylene glycol, respectively. The response of the SnO2 nanosheets exhibited a linear dependence on the ethylene glycol concentration from 5 to 1000 ppm. The excellent sensing performance was attributed to the present SnO2 nanoparticles with small size close to the Debye length, the larger specific surface, the high-energy exposed facets of the (101) surface, and the synergistic effects of the SnO2 nanoparticles of the nanosheets. PMID:29462938

Iron doped SnO2/Co3O4 nanocomposites synthesized by sol-gel and precipitation method for metronidazole antibiotic degradation.

PubMed

Agarwal, Shilpi; Tyagi, Inderjeet; Gupta, Vinod Kumar; Sohrabi, Maryam; Mohammadi, Sanaz; Golikand, Ahmad Nozad; Fakhri, Ali

2017-01-01

Sol-gel and precipitation reaction methods were used to synthesize Un-doped and Fe-doped SnO 2 /Co 3 O 4 nanocomposites under UV light; the synthesized nanocomposites were applied for the photocatalytic degradation of metronidazole antibiotic. The developed photo catalyst was well characterized using energy dispersive X-ray spectrometer (EDX), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FE-SEM), UV-Visible and photoluminescence (PL) spectroscopy. Effective parameters such as pH, photocatalyst dose and contact time was optimized and well investigated. From the obtained facts it is clear that the 98.3% of MTZ was degraded with in 15min, pH6 and 0.1g catalyst when the Fe molar ratio was 1:1 at %. As compared to results obtained from un-doped SnO 2 /Co 3 O 4 nanocomposites Fe doped SnO 2 /Co 3 O 4 nanocomposites possess greater photocatalytic efficiency. Copyright © 2016 Elsevier B.V. All rights reserved.

The effect of interaction between surface plasmons of gold nanoparticles and optical active centers on luminescence of Eu3+- doped Zn2SnO4 nanocrystals

NASA Astrophysics Data System (ADS)

Thien, Nguyen Duy; Vu, Le Van; Long, Nguyen Ngoc

2018-04-01

The enhancement and quenching of Eu3+ ion emission were investigated in Zn2SnO4:Eu3+@Au (ZTO:Eu3+@Au) nanocomposites. Under 361 nm excitation we revealed the extinction of the intrinsic defect emission and the enhancement of Eu3+ ion emission when Au content in samples is increased, but under excitation wavelength of 394 nm we observed only the suppression of Eu3+ ion emission. The cause of the observed PL behavior is related to the interaction between surface plasmon induced by gold nanoparticles and luminescence centers in the samples.

Ultrahigh-Performance Cu2ZnSnS4 Thin Film and Its Application in Microscale Thin-Film Lithium-Ion Battery: Comparison with SnO2.

PubMed

Lin, Jie; Guo, Jianlai; Liu, Chang; Guo, Hang

2016-12-21

To develop a high-performance anode for thin-film lithium-ion batteries (TFBs, with a total thickness on the scale of micrometers), a Cu 2 ZnSnS 4 (CZTS) thin film is fabricated by magnetron sputtering and exhibits an ultrahigh performance of 950 mAh g -1 even after 500 cycles, which is the highest among the reported CZTS for lithium storage so far. The characterization and electrochemical tests reveal that the thin-film structure and additional reactions both contribute to the excellent properties. Furthermore, the microscale TFBs with effective footprints of 0.52 mm 2 utilizing the CZTS thin film as anode are manufactured by microfabrication techniques, showing superior capability than the analogous TFBs with the SnO 2 thin film as anode. This work demonstrates the advantages of exploiting thin-film electrodes and novel materials into micropower sources by electronic manufacture methods.

Self-catalytic branch growth of SnO 2 nanowire junctions

NASA Astrophysics Data System (ADS)

Chen, Y. X.; Campbell, L. J.; Zhou, W. L.

2004-10-01

Multiple branched SnO2 nanowire junctions have been synthesized by thermal evaporation of SnO powder. Their nanostructures were studied by transmission electron microscopy and field emission scanning electron microcopy. It was observed that Sn nanoparticles generated from decomposition of the SnO powder acted as self-catalysts to control the SnO2 nanojunction growth. Orthorhombic SnO2 was found as a dominate phase in nanojunction growth instead of rutile structure. The branches and stems of nanojunctions were found to be an epitaxial growth by electron diffraction analysis and high-resolution electron microscopy observation. The growth directions of the branched SnO2 nanojunctions were along the orthorhombic [1 1 0] and [ 1 1 bar 0 ] . A self-catalytic vapor-liquid-solid growth mechanism is proposed to describe the growth process of the branched SnO2 nanowire junctions.

Facile synthesis of SnO2/α-Fe2O3 nanocomposite for supercapacitor capacitor applications

NASA Astrophysics Data System (ADS)

Rani, B. Jansi; Saravanakumar, B.; Ravi, G.; Yuvakkumar, R.

2018-05-01

Facile and economically viable one step hydrothermal route was adapted to synthesis SnO2/α-Fe2O3 nanocomposite with and without hexamine (HMT) as surfactant successfully. The formation of SnO2/α-Fe2O3 nanocomposite was confirmed through XRD, Raman, PL and FTIR studies. The presence of well defined XRD diffraction peaks of both SnO2 and α-Fe2O3 revealed the formation SnO2/α-Fe2O3 nanocomposite. The obtained characteristic Raman active (Eg+Eg+Eu+A2u) mode of vibrations confirmed the formation of SnO2/α-Fe2O3 nanocomposite. Photoluminescence study revealed the emission behavior of the product. Metal oxygen vibrations of Fe-O in both octahedral, tetrahedral sites and Sn-O were confirmed by the bands located at 466, 580 and 673 cm-1 respectively through FTIR. The spherical morphology of the product synthesized with and without the surfactant HMT has been revealed by SEM images. The electrochemical behavior of the product was investigated through CV and EIS studies in 1M Na2SO4 electrolyte solution and obtained the highest specific capacitance of 211.25 F/g at 5 mV for the surfactant assisted product.

FIB-tomographic studies on chemical vapor deposition grown SnO2 nanowire arrays on TiO2 (001)

NASA Astrophysics Data System (ADS)

Chen, Haoyun; Liu, Yi; Wu, Hong; Xiong, Xiang; Pan, Jun

2016-12-01

Tin oxide nanowire arrays on titania (001) have been successfully fabricated by chemical vapor deposition of Sn(O t Bu)4 precursor. The morphologies and structures of ordered SnO2 nanowires (NWs) were analyzed by cross-sectional SEM, HR-TEM and AFM. An FIB-tomography technique was applied in order to reconstruct a 3D presentation of ordered SnO2 nanowires. The achieved 3D analysis showed the spatial orientation and angles of ordered SnO2 NWs can be obtained in a one-shot experiment, and the distribution of Au catalysts showed the competition between 1D and 2D growth. The SnO2 nanowire arrays can be potentially used as a diameter- and surface-dependent sensing unit for the detection of gas- and bio-molecules.

Highly sensitive SnO2 sensor via reactive laser-induced transfer

PubMed Central

Palla Papavlu, Alexandra; Mattle, Thomas; Temmel, Sandra; Lehmann, Ulrike; Hintennach, Andreas; Grisel, Alain; Wokaun, Alexander; Lippert, Thomas

2016-01-01

Gas sensors based on tin oxide (SnO2) and palladium doped SnO2 (Pd:SnO2) active materials are fabricated by a laser printing method, i.e. reactive laser-induced forward transfer (rLIFT). Thin films from tin based metal-complex precursors are prepared by spin coating and then laser transferred with high resolution onto sensor structures. The devices fabricated by rLIFT exhibit low ppm sensitivity towards ethanol and methane as well as good stability with respect to air, moisture, and time. Promising results are obtained by applying rLIFT to transfer metal-complex precursors onto uncoated commercial gas sensors. We could show that rLIFT onto commercial sensors is possible if the sensor structures are reinforced prior to printing. The rLIFT fabricated sensors show up to 4 times higher sensitivities then the commercial sensors (with inkjet printed SnO2). In addition, the selectivity towards CH4 of the Pd:SnO2 sensors is significantly enhanced compared to the pure SnO2 sensors. Our results indicate that the reactive laser transfer technique applied here represents an important technical step for the realization of improved gas detection systems with wide-ranging applications in environmental and health monitoring control. PMID:27118531

AML1-ETO requires enhanced C/D box snoRNA/RNP formation to induce self-renewal and leukaemia.

PubMed

Zhou, Fengbiao; Liu, Yi; Rohde, Christian; Pauli, Cornelius; Gerloff, Dennis; Köhn, Marcel; Misiak, Danny; Bäumer, Nicole; Cui, Chunhong; Göllner, Stefanie; Oellerich, Thomas; Serve, Hubert; Garcia-Cuellar, Maria-Paz; Slany, Robert; Maciejewski, Jaroslaw P; Przychodzen, Bartlomiej; Seliger, Barbara; Klein, Hans-Ulrich; Bartenhagen, Christoph; Berdel, Wolfgang E; Dugas, Martin; Taketo, Makoto Mark; Farouq, Daneyal; Schwartz, Schraga; Regev, Aviv; Hébert, Josée; Sauvageau, Guy; Pabst, Caroline; Hüttelmaier, Stefan; Müller-Tidow, Carsten

2017-07-01

Leukaemogenesis requires enhanced self-renewal, which is induced by oncogenes. The underlying molecular mechanisms remain incompletely understood. Here, we identified C/D box snoRNAs and rRNA 2'-O-methylation as critical determinants of leukaemic stem cell activity. Leukaemogenesis by AML1-ETO required expression of the groucho-related amino-terminal enhancer of split (AES). AES functioned by inducing snoRNA/RNP formation via interaction with the RNA helicase DDX21. Similarly, global loss of C/D box snoRNAs with concomitant loss of rRNA 2'-O-methylation resulted in decreased leukaemia self-renewal potential. Genomic deletion of either C/D box snoRNA SNORD14D or SNORD35A suppressed clonogenic potential of leukaemia cells in vitro and delayed leukaemogenesis in vivo. We further showed that AML1-ETO9a, MYC and MLL-AF9 all enhanced snoRNA formation. Expression levels of C/D box snoRNAs in AML patients correlated closely with in vivo frequency of leukaemic stem cells. Collectively, these findings indicate that induction of C/D box snoRNA/RNP function constitutes an important pathway in leukaemogenesis.

Three-dimensional SnO2@TiO2 double-shell nanotubes on carbon cloth as a flexible anode for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Haifeng; Ren, Weina; Cheng, Chuanwei

2015-07-01

In this study, three-dimensional SnO2@TiO2 double-shell nanotubes on carbon cloth are synthesized by a combination of the hydrothermal method for ZnO nanorods and a subsequent SnO2 and TiO2 thin film coating with atomic layer deposition (ALD). The as-prepared SnO2@TiO2 double-shell nanotubes are further tested as a flexible anode for Li ion batteries. The SnO2@TiO2 double-shell nanotubes/carbon cloth electrode exhibited a high initial discharge capacity (e.g. 778.8 mA h g-1 at a high current density of 780 mA g-1) and good cycling performance, which could be attributed to the 3D double-layer nanotube structure. The interior space of the stable TiO2 hollow tube can accommodate the large internal stress caused by volume expansion of SnO2 and protect SnO2 from pulverization and exfoliation.

SnO2/TiO2 bilayer thin films exhibiting superhydrophilic properties

NASA Astrophysics Data System (ADS)

Talinungsang, Nibedita Paul; Purkayastha, Debarun Dhar

2017-05-01

Nanostructured thin films of TiO2, SnO2, and SnO2/TiO2 have been deposited by sol-gel method. The films are characterized by X-ray diffraction, wettability and optical properties. In the present work, we have achieved a way of converting hydrophilic to super-hydrophilic state by incorporating TiO2 buffer layer in between substrate and SnO2 film, which has its utility in anti-fogging surfaces. The decrease in contact angle of water over SnO2/TiO2 bilayer is attributed to the increase in roughness of the film as well as surface energy of the substrate.

CO2 Sensors Based on Nanocrystalline SnO2 Doped with CuO

NASA Technical Reports Server (NTRS)

Xu, Jennifer C.; Hunter, Gary W.; Liu, Chung Chiun; Ward, Benjamin J.

2008-01-01

Nanocrystalline tin oxide (SnO2) doped with copper oxide (CuO) has been found to be useful as an electrical-resistance sensory material for measuring the concentration of carbon dioxide in air. SnO2 is an n-type semiconductor that has been widely used as a sensing material for detecting such reducing gases as carbon monoxide, some of the nitrogen oxides, and hydrocarbons. Without doping, SnO2 usually does not respond to carbon dioxide and other stable gases. The discovery that the electrical resistance of CuO-doped SnO2 varies significantly with the concentration of CO2 creates opportunities for the development of relatively inexpensive CO2 sensors for detecting fires and monitoring atmospheric conditions. This discovery could also lead to research that could alter fundamental knowledge of SnO2 as a sensing material, perhaps leading to the development of SnO2-based sensing materials for measuring concentrations of oxidizing gases. Prototype CO2 sensors based on CuO-doped SnO2 have been fabricated by means of semiconductor-microfabrication and sol-gel nanomaterial-synthesis batch processes that are amendable to inexpensive implementation in mass production.

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

NASA Astrophysics Data System (ADS)

Patil, S. M.; Dhodamani, A. G.; Vanalakar, S. A.; Deshmukh, S. P.; Delekar, S. D.

2018-04-01

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.

Heterogeneous nanocrystals assembled TiO2/SnO2/C composite for improved lithium storage

NASA Astrophysics Data System (ADS)

Tian, Qinghua; Mao, Yuning; Zhang, Xuzhen; Yang, Li

2018-07-01

Using stable TiO2 and flexible carbon as double-functional structure protector of nanostructural SnO2 to fabricate TiO2/SnO2/C composites is widely considered as a favorable strategy for improving the lithium storage performance of SnO2 anodes. But, it is still a challenge to obtain a satisfying TiO2/SnO2/C composite. Herein, an interesting porous nanostructure of TiO2/SnO2/C nanosphere composite assembled by TiO2 and SnO2 nanocrystals with an outer carbon coating has been fabricated by a well-designed approach. Thanks to the perfectly combined action of porous spherical nanostructure, TiO2 and SnO2 nanocrystals and carbon coating, the as-prepared composite obtains excellent structure stability and improved electrochemcial properties. When used as a promising anode for lithium-ion batteres, it exhibits outstanding lithium storage performance, delivering a high capacity of 687.2 mAh g-1 after even 400 cycles.

Enhancement of visible light photocatalytic activity over bistructural SnO2 nanobelts

NASA Astrophysics Data System (ADS)

Wang, Lihua; Wang, Yongli; Su, Dezhi; Zhao, Yongjie

2018-02-01

SnO2 nanobelts were synthesized by hydrothermal method. The structure and morphology were investigated by XRD, Raman spectra, SEM and TEM. The results revealed that the synthesized SnO2 nanobelts were covered with amorphous surface. For the photocatalytic efficiency of methylene blue, the none-fully crystallized SnO2 nanobelts were over four times higher than bulk SnO2. Moreover, the photo-degradation rate constant with SnO2 nanobelts as photocatalysts was over six times higher than bulk SnO2. It was considered that the subtle structure of SnO2 nanobelts not only lowered the band gap but also improved the transfer of charge carriers and trapping effect of solar light. Furthermore, this strategy of enhancing photocatalytic performance could be extended to the other kinds of metal oxide photocatalyst.

PMA Induces SnoN Proteolysis and CD61 Expression through an Autocrine Mechanism

PubMed Central

Li, Chonghua; Peart, Natoya; Xuan, Zhenyu; Lewis, Dorothy E; Xia, Yang; Jin, Jianping

2014-01-01

Phorbol-12-myristate-13-acetate, also called PMA, is a small molecule that activates protein kinase C and functions to differentiate hematologic lineage cells. However, the mechanism of PMA-induced cellular differentiation is not fully understood. We found that PMA triggers global enhancement of protein ubiquitination in K562, a myelogenous leukemia cell line and one of the enhanced-ubiquitination targets is SnoN, an inhibitor of the Smad signaling pathway. Our data indicated that PMA stimulated the production of Activin A, a cytokine of the TGF-β family. Activin A then activated the phosphorylation of both Smad2 and Smad3. In consequence, SnoN is ubiquitinated by the APCCdh1 ubiquitin ligase with the help of phosphorylated Smad2. Furthermore, we found that SnoN proteolysis is important for the expression of CD61, a marker of megakaryocyte. These results indicate that protein ubiquitination promotes megakaryopoiesis via degrading SnoN, an inhibitor of CD61 expression, strengths the roles of ubiquitination in cellular differentiation. PMID:24637302

Metallic Sn spheres and SnO2@C core-shells by anaerobic and aerobic catalytic ethanol and CO oxidation reactions over SnO2 nanoparticles

PubMed Central

Kim, Won Joo; Lee, Sung Woo; Sohn, Youngku

2015-01-01

SnO2 has been studied intensely for applications to sensors, Li-ion batteries and solar cells. Despite this, comparatively little attention has been paid to the changes in morphology and crystal phase that occur on the metal oxide surface during chemical reactions. This paper reports anaerobic and aerobic ethanol and CO oxidation reactions over SnO2 nanoparticles (NPs), as well as the subsequent changes in the nature of the NPs. Uniform SnO2@C core-shells (10 nm) were formed by an aerobic ethanol oxidation reaction over SnO2 NPs. On the other hand, metallic Sn spheres were produced by an anaerobic ethanol oxidation reaction at 450 °C, which is significantly lower than that (1200 °C) used in industrial Sn production. Anaerobic and aerobic CO oxidation reactions were also examined. The novelty of the methods for the production of metallic Sn and SnO2@C core-shells including other anaerobic and aerobic reactions will contribute significantly to Sn and SnO2-based applications. PMID:26300041

Enhanced room temperature ferromagnetism in Ni doped SnO2 nanoparticles: A comprehensive study

NASA Astrophysics Data System (ADS)

Ahmed, Ateeq; Ali, T.; Naseem Siddique, M.; Ahmad, Abid; Tripathi, P.

2017-08-01

We emphasized on a detailed investigation of the structural, optical, and magnetic properties of pure and Ni-doped SnO2 nanoparticles (NPs) synthesized by a sol-gel process. An extensive structural study has been carried out using various characterization techniques. The X-ray Diffraction (XRD) spectra show the formation of the single phase tetragonal structure of pure and Ni-doped SnO2 NPs without any noticeable impurity phase such as NiO. XRD results indicate that the crystallite size of SnO2 is found to be decreased with Ni doping, which has also been confirmed by the Field Emission Scanning Electron Microscopy study. X-ray Photoelectron Spectroscopy (XPS) measurements displayed a clear sign for Ni2+ ions occupying the lattice sites of Sn4+ in the SnO2 host which also gives clear evidence for the formation of single phase Sn1-xNixO2 NPs. The optical analysis shows a significant decrease in the energy gap of SnO2, i.e., (from 3.71 eV to 3.28 eV) as Ni concentration increases which may be correlated with the core level valence band XPS analysis. Photoluminescence studies show that Ni doping creates oxygen vacancies due to dissimilar ionic radii of Ni2+ and Sn4+. Superconducting quantum interference device measurements revealed that the Ni doped SnO2 NPs exhibit strong ferromagnetic behavior at room temperature and this analysis has been well fitted with a simple relationship to find out magnetic parameters proposed by Stearns and Cheng et al. Hence, our results demonstrate that Ni-doping has strong impact on the structural, optical, and magnetic properties.

Porous SnO2-CuO nanotubes for highly reversible lithium storage

NASA Astrophysics Data System (ADS)

Cheong, Jun Young; Kim, Chanhoon; Jung, Ji-Won; Yoon, Ki Ro; Kim, Il-Doo

2018-01-01

Facile synthesis of rationally designed structures is critical to realize a high performance electrode for lithium-ion batteries (LIBs). Among different candidates, tin(IV) oxide (SnO2) is one of the most actively researched electrode materials due to its high theoretical capacity (1493 mAh g-1), abundance, inexpensive costs, and environmental friendliness. However, severe capacity decay from the volume expansion and low conductivity of SnO2 have hampered its use as a feasible electrode for LIBs. Rationally designed SnO2-based nanostructures with conductive materials can be an ideal solution to resolve such limitations. In this work, we have successfully fabricated porous SnO2-CuO composite nanotubes (SnO2-CuO p-NTs) by electrospinning and subsequent calcination step. The porous nanotubular structure is expected to mitigate the volume expansion of SnO2, while the as-formed Cu from CuO upon lithiation allows faster electron transport by improving the low conductivity of SnO2. With a synergistic effect of both Sn and Cu-based oxides, SnO2-CuO p-NTs deliver stable cycling performance (91.3% of capacity retention, ∼538 mAh g-1) even after 350 cycles at a current density of 500 mA g-1, along with enhanced rate capabilities compared with SnO2.

Thermoelectric Properties of Self Assembled TiO2/SnO2 Nanocomposites

NASA Technical Reports Server (NTRS)

Dynys, Fred; Sayir, Ali; Sehirlioglu, Alp

2008-01-01

Recent advances in improving efficiency of thermoelectric materials are linked to nanotechnology. Thermodynamically driven spinodal decomposition was utilized to synthesize bulk nanocomposites. TiO2/SnO2 system exhibits a large spinodal region, ranging from 15 to 85 mole % TiO2. The phase separated microstructures are stable up to 1400 C. Semiconducting TiO2/SnO2 powders were synthesized by solid state reaction between TiO2 and SnO2. High density samples were fabricated by pressureless sintering. Self assemble nanocomposites were achieved by annealing at 1000 to 1350 C. X-ray diffraction reveal phase separation of (Ti(x)Sn(1-x))O2 type phases. The TiO2/SnO2 nanocomposites exhibit n-type behavior; a power factor of 70 W/mK2 at 1000 C has been achieved with penta-valent doping. Seebeck, thermal conductivity, electrical resistivity and microstructure will be discussed in relation to composition and doping.

Soft exfoliation of 2D SnO with size-dependent optical properties

NASA Astrophysics Data System (ADS)

Singh, Mandeep; Della Gaspera, Enrico; Ahmed, Taimur; Walia, Sumeet; Ramanathan, Rajesh; van Embden, Joel; Mayes, Edwin; Bansal, Vipul

2017-06-01

Two-dimensional (2D) materials have recently gained unprecedented attention as potential candidates for next-generation (opto)electronic devices due to their fascinating optical and electrical properties. Tin monoxide, SnO, is an important p-type semiconductor with applications across photocatalysis (water splitting) and electronics (transistors). However, despite its potential in several important technological applications, SnO remains underexplored in its 2D form. Here we present a soft exfoliation strategy to produce 2D SnO nanosheets with tunable optical and electrical properties. Our approach involves the initial synthesis of layered SnO microspheres, which are readily exfoliated through a low-power sonication step to form high quality SnO nanosheets. We demonstrate that the properties of 2D SnO are strongly dependent on its dimensions. As verified through optical absorption and photoluminescence studies, a strong size-dependent quantum confinement effect in 2D SnO leads to substantial variation in its optical and electrical properties. This results in a remarkable (>1 eV) band gap widening in atomically thin SnO. Through photoconductivity measurements, we further validate a strong correlation between the quantum-confined properties of 2D SnO and the selective photoresponse of atomically thin sheets in the high energy UV light. Such tunable semiconducting properties of 2D SnO could be exploited for a variety of applications including photocatalysis, photovoltaics and optoelectronics in general.

Enhanced photovoltaic properties in dye sensitized solar cells by surface treatment of SnO2 photoanodes

PubMed Central

Basu, Kaustubh; Benetti, Daniele; Zhao, Haiguang; Jin, Lei; Vetrone, Fiorenzo; Vomiero, Alberto; Rosei, Federico

2016-01-01

We report the fabrication and testing of dye sensitized solar cells (DSSC) based on tin oxide (SnO2) particles of average size ~20 nm. Fluorine-doped tin oxide (FTO) conducting glass substrates were treated with TiOx or TiCl4 precursor solutions to create a blocking layer before tape casting the SnO2 mesoporous anode. In addition, SnO2 photoelectrodes were treated with the same precursor solutions to deposit a TiO2 passivating layer covering the SnO2 particles. We found that the modification enhances the short circuit current, open-circuit voltage and fill factor, leading to nearly 2-fold increase in power conversion efficiency, from 1.48% without any treatment, to 2.85% achieved with TiCl4 treatment. The superior photovoltaic performance of the DSSCs assembled with modified photoanode is attributed to enhanced electron lifetime and suppression of electron recombination to the electrolyte, as confirmed by electrochemical impedance spectroscopy (EIS) carried out under dark condition. These results indicate that modification of the FTO and SnO2 anode by titania can play a major role in maximizing the photo conversion efficiency. PMID:26988622

Thermoelectric Properties of Self Assemble TiO2/SnO2 Nanocomposites

NASA Technical Reports Server (NTRS)

Dynys, Fred; Sayir, Ali; Sehirlioglu, Alp

2008-01-01

Recent advances in improving efficiency of thermoelectric materials are linked to nanotechnology. Thermodynamically driven spinodal decomposition was utilized to synthesize bulk nanocomposites. TiO2/SnO2 system exhibits a large spinodal region, ranging from 15 to 85 mole % TiO2. The phase separated microstructures are stable up to 1400 C. Semiconducting TiO2/SnO2 powders were synthesized by solid state reaction between TiO2 and SnO2. High density samples were fabricated by pressureless sintering. Self assemble nanocomposites were achieved by annealing at 1000 to 1350 C. X-ray diffraction reveal phase separation of (Ti(x)Sn(1-x))O2 type phases. The TiO2/SnO2 nanocomposites exhibit n-type behavior; a power factor of 70 (mu)W/m sq K at 1000 C has been achieved with penta-valent doping. Seebeck, thermal conductivity, electrical resistivity and microstructure will be discussed in relation to composition and doping.

Designed hybrid nanostructure with catalytic effect: beyond the theoretical capacity of SnO2 anode material for lithium ion batteries

PubMed Central

Wang, Ye; Huang, Zhi Xiang; Shi, Yumeng; Wong, Jen It; Ding, Meng; Yang, Hui Ying

2015-01-01

Transition metal cobalt (Co) nanoparticle was designed as catalyst to promote the conversion reaction of Sn to SnO2 during the delithiation process which is deemed as an irreversible reaction. The designed nanocomposite, named as SnO2/Co3O4/reduced-graphene-oxide (rGO), was synthesized by a simple two-step method composed of hydrothermal (1st step) and solvothermal (2nd step) synthesis processes. Compared to the pristine SnO2/rGO and SnO2/Co3O4 electrodes, SnO2/Co3O4/rGO nanocomposites exhibit significantly enhanced electrochemical performance as the anode material of lithium-ion batteries (LIBs). The SnO2/Co3O4/rGO nanocomposites can deliver high specific capacities of 1038 and 712 mAh g−1 at the current densities of 100 and 1000 mA g−1, respectively. In addition, the SnO2/Co3O4/rGO nanocomposites also exhibit 641 mAh g−1 at a high current density of 1000 mA g−1 after 900 cycles, indicating an ultra-long cycling stability under high current density. Through ex-situ TEM analysis, the excellent electrochemical performance was attributed to the catalytic effect of Co nanoparticles to promote the conversion of Sn to SnO2 and the decomposition of Li2O during the delithiation process. Based on the results, herein we propose a new method in employing the catalyst to increase the capacity of alloying-dealloying type anode material to beyond its theoretical value and enhance the electrochemical performance. PMID:25776280

NO2 Gas Sensing Properties of Multiple Networked ZnGa2O4 Nanorods Coated with TiO2.

PubMed

An, Soyeon; Park, Sunghoon; Ko, Hyunsung; Jin, Changhyun; Lee, Chongmu

2015-01-01

The NO2 gas sensing properties of ZnGa2O4-TiO2 heterostructure nanorods was examined. ZnGa2O4-core/TiO2-shell nanorods were fabricated by the thermal evaporation of a mixture of Zn and GaN powders and the sputter deposition of TiO2. Multiple networked ZnGa2O4-core/TiO2-shell nanorod sensors showed the response of 876% at 10 ppm NO2 at 300 degrees C. This response value at 10 ppm NO2 is approximately 4 times larger than that of bare ZnGa2O4 nanorod sensors. The response values obtained by the ZnGa2O4-core/TiO2-shell nanorods in this study are more than 13 times higher than those obtained previously by the SnO2-core/ZnO-shell nanofibers at 5% NO2. The significant enhancement in the response of ZnGa2O4 nanorods to NO2 gas by coating them with TiO2 can be explained based on the space-charge model.

Effect of annealing temperature on optical and electrical properties of ZrO2-SnO2 based nanocomposite thin films

NASA Astrophysics Data System (ADS)

Anitha, V. S.; Lekshmy, S. Sujatha; Berlin, I. John; Joy, K.

2014-01-01

Transparent nanocomposite ZrO2-SnO2 thin films were prepared by sol-gel dip-coating technique. Films were annealed at 500°C, 800°C and 1200°C respectively. X-ray diffraction(XRD) spectra showed a mixture of three phases: tetragonal ZrO2 and SnO2 and orthorhombic ZrSnO4. The grain size of all the three phases' increased with annealing temperature. An average transmittance greater than 85%(in UV-Visible region) is observed for all the films. The band gap for the films decreased from 4.79 eV to 4.62 eV with increase in annealing temperature from 500 to 1200 °C. The electrical resistivity increased with increase in annealing temperature. Such composite ZrO2-SnO2 films can be used in many applications and in optoelectronic devices.

Superparamagnetic behavior of Fe-doped SnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Hachisu, M.; Onuma, K.; Kondo, T.; Miike, K.; Miyasaka, T.; Mori, K.; Ichiyanagi, Y.

2014-02-01

SnO2 is an n-type semiconductor with a wide band gap of 3.62 eV, and SnO2 nanoparticles doped with magnetic ions are expected to realized new diluted magnetic semiconductors (DMSs). Realizing ferromagnetism at room temperature is important for spintronics device applications, and it is interesting that the magnetic properties of these DMS systems can be varied significantly by modifying the preparation methods or conditions. In this study, the magnetic properties of Fe-doped (3% and 5%) SnO2 nanoparticles, prepared using our novel chemical preparation method and encapsulated in amorphous SiO2, were investigated. The particle size (1.8-16.9 nm) and crystal phase were controlled by the annealing temperature. X-ray diffraction confirmed a rutile SnO2 single-phase structure for samples annealed at 1073-1373 K, and the composition was confirmed using X-ray fluorescence analysis. SQUID magnetometer measurements revealed superparamagnetic behavior of the 5%-Fe-doped sample at room temperature, although SnO2 is known to be diamagnetic. Magnetization curves at 5 K indicated that the 3%-Fe-doped has a larger magnetization than that of the 5%-Fe-doped sample. We conclude that the magnetization of the 5%-Fe-doped sample decreased at 5 K due to the superexchange interaction between the antiferromagnetic coupling in the nanoparticle system.

Optimized photodegradation of Bisphenol A in water using ZnO, TiO2 and SnO2 photocatalysts under UV radiation as a decontamination procedure

NASA Astrophysics Data System (ADS)

Abo, Rudy; Kummer, Nicolai-Alexeji; Merkel, Broder J.

2016-09-01

Experiments on photodegradation of Bisphenol A (BPA) were carried out in water samples by means photocatalytic and photo-oxidation methods in the presence of ZnO, TiO2 and SnO2 catalysts. The objective of this study was to develop an improved technique that can be used as a remediation procedure for a BPA-contaminated surface water and groundwater based on the UV solar radiation. The photodegradation of BPA in water performed under a low-intensity UV source mimics the UVC and UVA spectrum of solar radiation between 254 and 365 nm. The archived results reveal higher degradation rates observed in the presence of ZnO than with TiO2 and SnO2 catalysts during 20 h of irradiation. The intervention of the advanced photocatalytic oxidation (PCO) reduces the time of degradation to less than 1 h to reach a degradation rate of 90 % for BPA in water. The study proposes the use of ZnO as a competitor catalyst to the traditional TiO2, providing the most effective treatment of contaminated water with phenolic products.

Functional and Structural Insights of the Zinc-Finger HIT protein family members Involved in Box C/D snoRNP Biogenesis.

PubMed

Bragantini, Benoit; Tiotiu, Decebal; Rothé, Benjamin; Saliou, Jean-Michel; Marty, Hélène; Cianférani, Sarah; Charpentier, Bruno; Quinternet, Marc; Manival, Xavier

2016-06-05

Zf–HIT family members share the zf–HIT domain (ZHD), which is characterized by a fold in “treble-clef” through interleaved CCCC and CCHC ZnF motifs that both bind a zinc atom. Six proteins containing ZHD are present in human and three in yeast proteome, all belonging to multimodular RNA/protein complexes involved in gene regulation, chromatin remodeling, and snoRNP assembly. An interesting characteristic of the cellular complexes that ensure these functions is the presence of the RuvBL1/2/Rvb1/2 ATPases closely linked with zf–HIT proteins. Human ZNHIT6/BCD1 and its counterpart in yeast Bcd1p were previously characterized as assembly factors of the box C/D snoRNPs. Our data reveal that the ZHD of Bcd1p is necessary but not sufficient for yeast growth and that the motif has no direct RNA-binding capacity but helps Bcd1p maintain the box C/D snoRNAs level in steady state. However, we demonstrated that Bcd1p interacts nonspecifically with RNAs depending on their length. Interestingly, the ZHD of Bcd1p is functionally interchangeable with that of Hit1p, another box C/D snoRNP assembly factor belonging to the zf–HIT family. This prompted us to use NMR to solve the 3D structures of ZHD from yeast Bcd1p and Hit1p to highlight the structural similarity in the zf–HIT family. We identified structural features associated with the requirement of Hit1p and Bcd1p ZHD for cell growth and box C/D snoRNA stability under heat stress. Altogether, our data suggest an important role of ZHD could be to maintain functional folding to the rest of the protein, especially under heat stress conditions.

Selective Improvement of NO2 Gas Sensing Behavior in SnO2 Nanowires by Ion-Beam Irradiation.

PubMed

Kwon, Yong Jung; Kang, Sung Yong; Wu, Ping; Peng, Yuan; Kim, Sang Sub; Kim, Hyoun Woo

2016-06-01

We irradiated SnO2 nanowires with He ions (45 MeV) with different ion fluences. Structure and morphology of the SnO2 nanowires did not undergo noticeable changes upon ion-beam irradiation. Chemical equilibrium in SnO2/gas systems was calculated from thermodynamic principles, which were used to study the sensing selectivity of the tested gases, demonstrating the selective sensitivity of the SnO2 surface to NO2 gas. Being different from other gases, including H2, ethanol, acetone, SO2, and NH3, the sensor response to NO2 gas significantly increases as the ion fluence increases, showing a maximum under an ion fluence of 1 × 10(16) ions/cm(2). Photoluminescence analysis shows that the relative intensity of the peak at 2.1 eV to the peak at 2.5 eV increases upon ion-beam irradiation, suggesting that structural defects and/or tin interstitials have been generated. X-ray photoelectron spectroscopy indicated that the ionic ratio of Sn(2+/)Sn(4+) increases by the ion-beam irradiation, supporting the formation of surface Sn interstitials. Using thermodynamic calculations, we explained the observed selective sensing behavior. A molecular level model was also established for the adsorption of NO2 on ion-irradiated SnO2 (110) surfaces. We propose that the adsorption of NO2-related species is considerably enhanced by the generation of surface defects that are comprised of Sn interstitials.

Facile fabrication of robust TiO2@SnO2@C hollow nanobelts for outstanding lithium storage

NASA Astrophysics Data System (ADS)

Tian, Qinghua; Li, Lingxiangyu; Chen, Jizhang; Yang, Li; Hirano, Shin-ichi

2018-02-01

Elaborate fabrication of state-of-the-art nanostructure SnO2@C-based composites greatly contributes to alleviate the huge volume expansion issue of the SnO2 anodes. But the preparation processes of most of them are complicated and tedious, which is generally adverse to the development of SnO2@C-based composite anodes. Herein, a unique nanostructure of TiO2@SnO2@C hollow nanobelts (TiO2@SnO2@C HNBs), including the characteristics of one-dimensional architecture, sandwich protection, hollow structure, carbon coating, and a mechanically robust TiO2 support, has been fabricated by a facile approach for the first time. As anodes for lithium-ion batteries, the as-fabricated TiO2@SnO2@C HNBs exhibit an outstanding lithium storage performance, delivering capacity of 804.6 and 384. 5 mAh g-1 at 200 and even 1000 mA g-1 after 500 cycles, respectively. It is demonstrated that thus outstanding performance is mainly attributed to the unique nanostructure of TiO2@SnO2@C HNBs.

Fabrication of SnO2-TiO2 core-shell nanopillar-array films for enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Cheng, Hsyi-En; Lin, Chun-Yuan; Hsu, Ching-Ming

2017-02-01

Immobilized or deposited thin film TiO2 photocatalysts are suffering from a low photocatalytic activity due to either a low photon absorption efficiency or a high carrier recombination rate. Here we demonstrate that the photocatalytic activity of TiO2 can be effectively improved by the SnO2-TiO2 core-shell nanopillar-array structure which combines the benefits of SnO2/TiO2 heterojunction and high reaction surface area. The SnO2-TiO2 core-shell nanopillar-array films were fabricated using atomic layer deposition and dry etching techniques via barrier-free porous anodic alumina templates. The photocatalytic activity of the prepared films was evaluated by methylene blue (MB) bleaching under 352 nm UV light irradiation. The results show that the photocatalytic activity of TiO2 film was 45% improved by introducing a SnO2 film between TiO2 and ITO glass substrate and was 300% improved by using the SnO2-TiO2 core-shell nanopillar-array structure. The 45% improvement by the SnO2 interlayer is attributed to the SnO2/TiO2 heterojunction which separates the photogenerated electron-hole pairs in TiO2 for MB degradation, and the high photocatalytic activity of the SnO2-TiO2 core-shell nanopillar-array films is attributed to the three dimensional SnO2/TiO2 heterojunction which owns both the carrier separation ability and the high photocatalytic reaction surface area.

Highly enhanced ultraviolet photosensitivity and recovery speed in electrospun Ni-doped SnO2 nanobelts

NASA Astrophysics Data System (ADS)

Huang, Siya; Matsubara, Kohei; Cheng, Jing; Li, Heping; Pan, Wei

2013-09-01

Precisely controlled Ni-doped SnO2 (NSO) nanobelt arrays are synthesized and assembled via electrospinning. In comparison to pristine SnO2 nanobelts, enhanced photosensitivity (˜103) as well as recovery speed (˜1 s) is obtained in NSO nanobelts. The mechanism is clarified by the compensation effect of acceptor impurity Ni, which not only promotes the oxygen-surface interaction but also introduces trapping centers in SnO2 matrix. The reduced grain size (˜4 nm) along with increased depletion layer thickness also benefits the photosensitivity of NSO nanobelts. These improved photoresponse properties make the NSO nanobelt a promising candidate for high-performance ultraviolet detectors.

Hierarchical MnO2/SnO2 heterostructures for a novel free-standing ternary thermite membrane.

PubMed

Yang, Yong; Zhang, Zhi-Cheng; Wang, Peng-Peng; Zhang, Jing-Chao; Nosheen, Farhat; Zhuang, Jing; Wang, Xun

2013-08-19

We report the synthesis of a novel hierarchical MnO2/SnO2 heterostructures via a hydrothermal method. Secondary SnO2 nanostructure grows epitaxially on the surface of MnO2 backbones without any surfactant, which relies on the minimization of surface energy and interfacial lattice mismatch. Detailed investigations reveal that the cover density and morphology of the SnO2 nanostructure can be tailored by changing the experimental parameter. Moreover, we demonstrate a bottom-up method to produce energetic nanocomposites by assembling nanoaluminum (n-Al) and MnO2/SnO2 hierarchical nanostructures into a free-standing MnO2/SnO2/n-Al ternary thermite membrane. This assembled approach can significantly reduce diffusion distances and increase their intimacy between the components. Different thermite mixtures were investigated to evaluate the corresponding activation energies using DSC techniques. The energy performance of the ternary thermite membrane can be manipulated through different components of the MnO2/SnO2 heterostructures. Overall, our work may open a new route for new energetic materials.

Photocurrent generation in SnO2 thin film by surface charged chemisorption O ions

NASA Astrophysics Data System (ADS)

Lee, Po-Ming; Liao, Ching-Han; Lin, Chia-Hua; Liu, Cheng-Yi

2018-06-01

We report a photocurrent generation mechanism in the SnO2 thin film surface layer by the charged chemisorption O ions on the SnO2 thin film surface induced by O2-annealing. A critical build-in electric field in the SnO2 surface layer resulted from the charged O ions on SnO2 surface prolongs the lifetime and reduces the recombination probability of the photo-excited electron-hole pairs by UV-laser irradiation (266 nm) in the SnO2 surface layer, which is the key for the photocurrent generation in the SnO2 thin film surface layer. The critical lifetime of prolonged photo-excited electron-hole pair is calculated to be 8.3 ms.

Self-cleaning antimicrobial surfaces by bio-enabled growth of SnO2 coatings on glass

NASA Astrophysics Data System (ADS)

André, Rute; Natalio, Filipe; Tahir, Muhammad Nawaz; Berger, Rüdiger; Tremel, Wolfgang

2013-03-01

photoactivity - creates a self-cleaning surface. The intrinsic self-cleaning properties could lead to the development of new protective, antifouling coatings on various substrates. Electronic supplementary information (ESI) available: (1) QCM measurement of SnO2 deposition on spermine functionalized silica-based sensors, (2) scheme of the surface functionalization procedure, (3) FTIR-ATR analysis of polyamine (spermine) functionalized glass surfaces, (4) FITC staining of amine groups on glass surfaces, (5) AFM height analysis of bare, spermine coated and SnO2 coated glass slides, (6) SEM micrograph of a spermine functionalized SnO2 coated glass slide, (7) XPS analysis of SnO2 coated surfaces, (8) kinetic profile of rhodamine B degradation with spermine/SnO2, (9) control experiments for the photodegradation of rhodamine B, (10) comparison with commercial SnO2 catalyst, (11) incubation of non-functionalized glass surfaces with E. coli, and (12) incubation of SnO2 coated glass surfaces with E. coli. See DOI: 10.1039/c3nr00007a

Structural and optical characterization of p-type highly Fe-doped SnO2 thin films and tunneling transport on SnO2:Fe/p-Si heterojunction

NASA Astrophysics Data System (ADS)

Ben Haj Othmen, Walid; Ben Hamed, Zied; Sieber, Brigitte; Addad, Ahmed; Elhouichet, Habib; Boukherroub, Rabah

2018-03-01

Nanocrystalline highly Fe-doped SnO2 thin films were prepared using a new simple sol-gel method with iron amounts of 5, 10, 15 and 20%. The obtained gel offers a long durability and high quality allowing to reach a sub-5 nm nanocrystalline size with a good crystallinity. The films were structurally characterized through X-ray diffraction (XRD) that confirms the formation of rutile SnO2. High Resolution Transmission Electron Microscopy (HRTEM) images reveals the good crystallinity of the nanoparticles. Raman spectroscopy shows that the SnO2 rutile structure is maintained even for high iron concentration. The variation of the PL intensity with Fe concentration reveals that iron influences the distribution of oxygen vacancies in tin oxide. The optical transmittance results indicate a redshift of the SnO2 band gap when iron concentration increases. The above optical results lead us to assume the presence of a compensation phenomenon between oxygen vacancies and introduced holes following Fe doping. From current-voltage measurements, an inversion of the conduction type from n to p is strongly predicted to follow the iron addition. Electrical characterizations of SnO2:Fe/p-Si and SnO2:Fe/n-Si heterojunctions seem to be in accordance with this deduction. The quantum tunneling mechanism is expected to be important at high Fe doping level, which was confirmed by current-voltage measurements at different temperatures. Both optical and electrical properties of the elaborated films present a particularity for the same iron concentration and adopt similar tendencies with Fe amount, which strongly correlate the experimental observations. In order to evaluate the applicability of the elaborated films, we proceed to the fabrication of the SnO2:Fe/SnO2 homojunction for which we note a good rectifying behavior.

Microstructural, Optical and Dielectric Properties of Al-Incorporated SnO2 Nanoparticles

NASA Astrophysics Data System (ADS)

Ahmed, Ateeq; Tripathi, P.; Naseem Siddique, M.; Ali, Tinku

2017-08-01

In this work, Pure SnO2 and Al doped SnO2 nanoparticles with the composition Sn1-xAlxO2 (x = 0, and 0.05) have been successfully prepared using sol-gel technique. The effect of Al dopant on microstructural, optical and dielectric properties has been investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Ultraviolet (UV-Visible) absorption spectroscopy andImpedance spectroscopy (LCR meter)respectively. The XRD patterns indicated tetragonal rutile structure with single phase without any detectable impurity for all samples and incorporation of Al ions into the SnO2 lattice. Crystalline size decreased with aluminum content. The results of SEM confirm nanoparticles size decreases with Al dopant. UV-Visible results showed that optical band also decreases when Al is doped into pure SnO2 lattice. Frequency dependent dielectric properties of pure and doped SnO2 nanoparticles have been also studied.

Shape Engineering Driven by Selective Growth of SnO2 on Doped Ga2O3 Nanowires.

PubMed

Alonso-Orts, Manuel; Sánchez, Ana M; Hindmarsh, Steven A; López, Iñaki; Nogales, Emilio; Piqueras, Javier; Méndez, Bianchi

2017-01-11

Tailoring the shape of complex nanostructures requires control of the growth process. In this work, we report on the selective growth of nanostructured tin oxide on gallium oxide nanowires leading to the formation of SnO 2 /Ga 2 O 3 complex nanostructures. Ga 2 O 3 nanowires decorated with either crossing SnO 2 nanowires or SnO 2 particles have been obtained in a single step treatment by thermal evaporation. The reason for this dual behavior is related to the growth direction of trunk Ga 2 O 3 nanowires. Ga 2 O 3 nanowires grown along the [001] direction favor the formation of crossing SnO 2 nanowires. Alternatively, SnO 2 forms rhombohedral particles on [110] Ga 2 O 3 nanowires leading to skewer-like structures. These complex oxide structures were grown by a catalyst-free vapor-solid process. When pure Ga and tin oxide were used as source materials and compacted powders of Ga 2 O 3 acted as substrates, [110] Ga 2 O 3 nanowires grow preferentially. High-resolution transmission electron microscopy analysis reveals epitaxial relationship lattice matching between the Ga 2 O 3 axis and SnO 2 particles, forming skewer-like structures. The addition of chromium oxide to the source materials modifies the growth direction of the trunk Ga 2 O 3 nanowires, growing along the [001], with crossing SnO 2 wires. The SnO 2 /Ga 2 O 3 junctions does not meet the lattice matching condition, forming a grain boundary. The electronic and optical properties have been studied by XPS and CL with high spatial resolution, enabling us to get both local chemical and electronic information on the surface in both type of structures. The results will allow tuning optical and electronic properties of oxide complex nanostructures locally as a function of the orientation. In particular, we report a dependence of the visible CL emission of SnO 2 on its particular shape. Orange emission dominates in SnO 2 /Ga 2 O 3 crossing wires while green-blue emission is observed in SnO 2 particles attached to Ga 2

Microwave-Hydrothermal Synthesis of SnO2-CNTs Hybrid Nanocomposites with Visible Light Photocatalytic Activity.

PubMed

Wu, Shuisheng; Dai, Weili

2017-03-03

SnO2 nanoparticles coated on carbon nanotubes (CNTs) were prepared via a simple microwave-hydrothermal route. The as-obtained SnO2-CNTs composites were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The photocatalytic activity of as-prepared SnO2-CNTs for degradation of Rhodamine B under visible light irradiation was investigated. The results show that SnO2-CNTs nanocomposites have a higher photocatalytic activity than pure SnO2 due to the rapid transferring of electrons and the effective separation of holes and electrons on SnO2-CNTs.

Microwave-Hydrothermal Synthesis of SnO2-CNTs Hybrid Nanocomposites with Visible Light Photocatalytic Activity

PubMed Central

Wu, Shuisheng; Dai, Weili

2017-01-01

SnO2 nanoparticles coated on carbon nanotubes (CNTs) were prepared via a simple microwave-hydrothermal route. The as-obtained SnO2-CNTs composites were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The photocatalytic activity of as-prepared SnO2-CNTs for degradation of Rhodamine B under visible light irradiation was investigated. The results show that SnO2-CNTs nanocomposites have a higher photocatalytic activity than pure SnO2 due to the rapid transferring of electrons and the effective separation of holes and electrons on SnO2-CNTs. PMID:28336888

A computational search for box C/D snoRNA genes in the Drosophila melanogaster genome.

PubMed

Accardo, M C; Giordano, E; Riccardo, S; Digilio, F A; Iazzetti, G; Calogero, R A; Furia, M

2004-12-12

In eukaryotes, the family of non-coding RNA genes includes a number of genes encoding small nucleolar RNAs (mainly C/D and H/ACA snoRNAs), which act as guides in the maturation or post-transcriptional modifications of target RNA molecules. Since in Drosophila melanogaster (Dm) only few examples of snoRNAs have been identified so far by cDNA libraries screening, integration of the molecular data with in silico identification of these types of genes could throw light on their organization in the Dm genome. We have performed a computational screening of the Dm genome for C/D snoRNA genes, followed by experimental validation of the putative candidates. Few of the 26 confirmed snoRNAs had been recognized by cDNA library analysis. Organization of the Dm genome was also found to be more variegated than previously suspected, with snoRNA genes nested in both the introns and exons of protein-coding genes. This finding suggests that the presence of additional mechanisms of snoRNA biogenesis based on the alternative production of overlapping mRNA/snoRNA molecules. Additional information is available at http://www.bioinformatica.unito.it/bioinformatics/snoRNAs.

High Efficiency Dye-sensitized Solar Cells Constructed with Composites of TiO2 and the Hot-bubbling Synthesized Ultra-Small SnO2 Nanocrystals.

PubMed

Mao, Xiaoli; Zhou, Ru; Zhang, Shouwei; Ding, Liping; Wan, Lei; Qin, Shengxian; Chen, Zhesheng; Xu, Jinzhang; Miao, Shiding

2016-01-13

An efficient photo-anode for the dye-sensitized solar cells (DSSCs) should have features of high loading of dye molecules, favorable band alignments and good efficiency in electron transport. Herein, the 3.4 nm-sized SnO2 nanocrystals (NCs) of high crystallinity, synthesized via the hot-bubbling method, were incorporated with the commercial TiO2 (P25) particles to fabricate the photo-anodes. The optimal percentage of the doped SnO2 NCs was found at ~7.5% (SnO2/TiO2, w/w), and the fabricated DSSC delivers a power conversion efficiency up to 6.7%, which is 1.52 times of the P25 based DSSCs. The ultra-small SnO2 NCs offer three benefits, (1) the incorporation of SnO2 NCs enlarges surface areas of the photo-anode films, and higher dye-loading amounts were achieved; (2) the high charge mobility provided by SnO2 was confirmed to accelerate the electron transport, and the photo-electron recombination was suppressed by the highly-crystallized NCs; (3) the conduction band minimum (CBM) of the SnO2 NCs was uplifted due to the quantum size effects, and this was found to alleviate the decrement in the open-circuit voltage. This work highlights great contributions of the SnO2 NCs to the improvement of the photovoltaic performances in the DSSCs.

High Efficiency Dye-sensitized Solar Cells Constructed with Composites of TiO2 and the Hot-bubbling Synthesized Ultra-Small SnO2 Nanocrystals

PubMed Central

Mao, Xiaoli; Zhou, Ru; Zhang, Shouwei; Ding, Liping; Wan, Lei; Qin, Shengxian; Chen, Zhesheng; Xu, Jinzhang; Miao, Shiding

2016-01-01

An efficient photo-anode for the dye-sensitized solar cells (DSSCs) should have features of high loading of dye molecules, favorable band alignments and good efficiency in electron transport. Herein, the 3.4 nm-sized SnO2 nanocrystals (NCs) of high crystallinity, synthesized via the hot-bubbling method, were incorporated with the commercial TiO2 (P25) particles to fabricate the photo-anodes. The optimal percentage of the doped SnO2 NCs was found at ~7.5% (SnO2/TiO2, w/w), and the fabricated DSSC delivers a power conversion efficiency up to 6.7%, which is 1.52 times of the P25 based DSSCs. The ultra-small SnO2 NCs offer three benefits, (1) the incorporation of SnO2 NCs enlarges surface areas of the photo-anode films, and higher dye-loading amounts were achieved; (2) the high charge mobility provided by SnO2 was confirmed to accelerate the electron transport, and the photo-electron recombination was suppressed by the highly-crystallized NCs; (3) the conduction band minimum (CBM) of the SnO2 NCs was uplifted due to the quantum size effects, and this was found to alleviate the decrement in the open-circuit voltage. This work highlights great contributions of the SnO2 NCs to the improvement of the photovoltaic performances in the DSSCs. PMID:26758941

Study of lattice strain and optical properties of nanocrystalline SnO2

NASA Astrophysics Data System (ADS)

Ahmad, Naseem; Khan, Shakeel; Bhargava, Richa; Ansari, Mohd Mohsin Nizam

2018-05-01

Nanocrystalline SnO2 has been synthesized by co-precipitation method by using two solvents (water and ethylene glycol). The structure and surface morphology were investigated using XRD and scanning electron microscope (SEM). The optical properties were studied using diffused reflectance spectroscopy (DRS). From the XRD analysis, the prepared materials are found to be pure crystalline with tetragonal rutile structure. The lattice strain and crystallite size, were calculated using Williamson-Hall method, are found to be 0.00413 & 16.3 nm in water assisted SnO2 and 0.00495 & 35.6 nm for EG assisted SnO2. Study of surface morphology of the samples was carried out using SEM. It has been seen that the solvents which are used in synthesis can also alter the optical properties of the materials. The optical band gap of the water based SnO2 and EG based SnO2 are found to be 3.92eV and 3.86eV respectively.

Size effect of SnO2 nanoparticles on bacteria toxicity and their membrane damage.

PubMed

Chávez-Calderón, Adriana; Paraguay-Delgado, Francisco; Orrantia-Borunda, Erasmo; Luna-Velasco, Antonia

2016-12-01

Semiconductor SnO 2 nanoparticles (NPs) are being exploited for various applications, including those in the environmental context. However, toxicity studies of SnO 2 NPs are very limited. This study evaluated the toxic effect of two sizes of spherical SnO 2 NPs (2 and 40 nm) and one size of flower-like SnO 2 NPs (800 nm) towards the environmental bacteria E. coli and B. subtilis. SnO 2 NPs were synthesized using a hydrothermal or calcination method and they were well characterized prior to toxicity assessment. To evaluate toxicity, cell viability and membrane damage were determined in cells (1 × 10 9  CFU mL -1 ) exposed to up to 1000 mg L -1 of NPs, using the plate counting method and confocal laser scanning microscopy. Spherical NPs of smaller primary size (E2) had the lowest hydrodynamic size (226 ± 96 nm) and highest negative charge (-30.3 ± 10.1 mV). Smaller spherical NPs also showed greatest effect on viability (IC 50  > 500 mg L -1 ) and membrane damage of B. subtilis, whereas E. coli was unaffected. Scanning electron microscopy confirmed the membrane damage of exposed B. subtilis and also exhibited the attachment of E2 NPs to the cell surface, as well as the elongation of cells. It was also apparent that toxicity was caused solely by NPs, as released Sn 4+ was not toxic to B. subtilis. Thus, surface charge interaction between negatively charged SnO 2 NPs and positively charged molecules on the membrane of the Gram positive B. subtilis was indicated as the key mechanism related to toxicity of NPs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Facile fabrication of a well-ordered porous Cu-doped SnO2 thin film for H2S sensing.

PubMed

Zhang, Shumin; Zhang, Pingping; Wang, Yun; Ma, Yanyun; Zhong, Jun; Sun, Xuhui

2014-09-10

Well-ordered Cu-doped and undoped SnO2 porous thin films with large specific surface areas have been fabricated on a desired substrate using a self-assembled soft template combined with simple physical cosputtering deposition. The Cu-doped SnO2 porous film gas sensor shows a significant enhancement in its sensing performance, including a high sensitivity, selectivity, and a fast response and recovery time. The sensitivity of the Cu-doped SnO2 porous sensor is 1 order of magnitude higher than that of the undoped SnO2 sensor, with average response and recovery times to 100 ppm of H2S of ∼ 10.1 and ∼ 42.4 s, respectively, at the optimal operating temperature of 180 °C. The well-defined porous sensors fabricated by the method also exhibit high reproducibility because of the accurately controlled fabrication process. The facile process can be easily extended to the fabrication of other semiconductor oxide gas sensors with easy doping and multilayer porous nanostructure for practical sensing applications.

Identification of a novel box C/D snoRNA from mouse nucleolar cDNA library.

PubMed

Zhou, Hui; Zhao, Jin; Yu, Chuan-He; Luo, Qing-Jun; Chen, Yue-Qin; Xiao, Yu; Qu, Liang-Hu

2004-02-18

By construction and screen of mouse nucleolar cDNA library, a novel mammalian small nucleolar RNAs (snoRNA) was identified. The novel snoRNA, 70 nt in length, displays structural features typical of C/D box snoRNA family. The snoRNA possesses an 11-nt-long rRNA antisense element and is predicted to guide the 2'-O-methylation of mouse 28S rRNA at G4043, a site unknown so far to be modified in vertebrates. The comparison of functional element of snoRNA guides among eukaryotes reveals that the novel snoRNA is a mammalian counterpart of yeast snR38 despite highly divergent sequence between them. Mouse and human snR38 and other cognates in distant vertebrates were positively detected with slight length variability. As expected, the rRNA ribose-methylation site predicted by mouse snR38 was precisely mapped by specific-primer extension assay. Furthermore, our analyses show that mouse and human snR38 gene have multiple variants and are nested in the introns of different host genes with unknown function. Thus, snR38 is a phylogenetically conserved methylation guide but exhibits different genomic organization in eukaryotes.

Synthesis and Gas Sensing Properties of Single La-Doped SnO2 Nanobelts

PubMed Central

Wu, Yuemei; Zhang, Heng; Liu, Yingkai; Chen, Weiwu; Ma, Jiang; Li, Shuanghui; Qin, Zhaojun

2015-01-01

Single crystal SnO2 nanobelts (SnO2 NBs) and La-SnO2 nanobelts (La-SnO2 NBs) were synthesized by thermal evaporation. Both a single SnO2 NB sensor and a single La-SnO2 NB sensor were developed and their sensing properties were investigated. It is found that the single La-SnO2 NB sensor had a high sensitivity of 8.76 to ethanediol at a concentration of 100 ppm at 230 °C, which is the highest sensitivity of a single SnO2 NB to ethanediol among three kinds of volatile organic (VOC) liquids studied, including ethanediol, ethanol, and acetone. The La-SnO2 NBs sensor also exhibits a high sensitivity, good selectivity and long-term stability with prompt response time to ethanediol. The mechanism behind the enhanced sensing performance of La-doped SnO2 nanobelts is discussed. PMID:26087374

Are Ski and SnoN Involved in the Tumorigenesis of Oral Squamous Cell Carcinoma Through Smad4?

PubMed

Alaeddini, Mojgan; Etemad-Moghadam, Shahroo

2018-05-04

Transforming growth factor-β has been implicated in the tumorigenesis of oral squamous cell carcinoma (OSCC). Ski and SnoN are negative regulators of transforming growth factor-β/Smad pathway with both prooncogenic and antioncogenic functions in different cancers. The aim of this study was to assess the expression of Ski and SnoN in OSCC for the first time. Smad4 was also evaluated in these tumors. Clinical data on 61 primary OSCCs were gathered, and the specimens were subjected to immunohistochemical staining with monoclonal antibodies against SKI, SnoN, and Smad4 and scored semiquantitatively. Spearman rank, Fisher exact, and χ tests were used for statistical analysis, and P-value <0.05 was considered significant. Ski positivity and SnoN positivity were mostly cytoplasmic and found in 96.7% and 100% of the cases, respectively. Smad4 staining was low to negative in 65% of the specimens. No significant relationship was found either among the markers or between each of the proteins and the clinicopathologic data (P>0.05). According to our findings, Ski, SnoN, and Smad4 seem to play a role in OSCC oncogenesis, and we suggest that Ski and SnoN functions may take place independent of Smad4. Considering the dual and complex role of these proteins in tumorigenesis, further investigation to clarify the molecular pathways involved in their mode of action is suggested.

Novel Chemoresistive CH4 Sensor with 10 ppm Sensitivity Based on Multi-Walled Carbon Nanotubes (MWCNTs) Functionalized with SnO2nanocrystals

EPA Science Inventory

Chemoresistive sensors based on multi-walled carbon nanotubes (MWCNTs)functionalized with SnO2 nanocrystals have great potential for detecting trace gases at low concentrations (single ppm levels) at room temperature, because the SnO2 nanocrystals act as active sites for the chem...

Electrospinning Hetero-Nanofibers In2O3/SnO2 of Homotype Heterojunction with High Gas Sensing Activity

PubMed Central

Du, Haiying; Yao, PengJun; Sun, Yanhui; Wang, Jing; Wang, Huisheng; Yu, Naisen

2017-01-01

In2O3/SnO2 composite hetero-nanofibers were synthesized by an electrospinning technique for detecting indoor volatile organic gases. The physical and chemical properties of In2O3/SnO2 hetero-nanofibers were characterized and analyzed by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), Energy Dispersive X-Ray Spectroscopy (EDX), specific surface Brunauer–Emmett–Teller (BET) and X-ray photoelectron spectroscopy (XPS). Gas sensing properties of In2O3/SnO2 composite hetero-nanofibers were measured with six kinds of indoor volatile organic gases in concentration range of 0.5~50 ppm at the operating temperature of 275 °C. The In2O3/SnO2 composite hetero-nanofibers sensor exhibited good formaldehyde sensing properties, which would be attributed to the formation of n-n homotype heterojunction in the In2O3/SnO2 composite hetero-nanofibers. Finally, the sensing mechanism of the In2O3/SnO2 composite hetero-nanofibers was analyzed based on the energy-band principle. PMID:28792433

SnO2/CNT nanocomposite supercapacitors fabricated using scanning atmospheric-pressure plasma jets

NASA Astrophysics Data System (ADS)

Xu, Chang-Han; Chiu, Yi-Fan; Yeh, Po-Wei; Chen, Jian-Zhang

2016-08-01

SnO2/CNT electrodes for supercapacitors are fabricated by first screen-printing pastes containing SnO2 nanoparticles and CNTs on carbon cloth, following which nitrogen atmospheric pressure plasma jet (APPJ) sintering is performed at various APPJ scan rates. The APPJ scan rates change the time intervals for which the reactive plasma species and the heat of the nitrogen APPJs influence the designated sintering spot on the carbon cloth, resulting in APPJ-sintered SnO2/CNT nanocomposites with different properties. The water contact angle decreases with the APPJ scan rate. The improved wettability can facilitate the penetration of the electrolyte into the nanopores of the SnO2/CNT nanocomposites, thereby improving the charge storage and specific capacitance of the supercapacitors. Among the three tested APPJ scan rates, 1.5, 3, and 6 mm s-1, the SnO2/CNT supercapacitor sintered by APPJ under the lowest APPJ scan rate of 1.5 mm s-1 shows the best specific capacitance of ˜90 F g-1 as evaluated by cyclic voltammetry under a potential scan rate of 2 mV s-1. A high APPJ scan rate may result in low degree of materials activation and sintering, leading to poorer performance of SnO2/CNT supercapacitors. The results suggest the feasibility of an APPJ roll-to-roll process for the fabrication of SnO2/CNT nanocomposite supercapacitors.

Heterojunction Fe2O3-SnO2 Nanostructured Photoanode for Efficient Photoelectrochemical Water Splitting

NASA Astrophysics Data System (ADS)

Han, Hyun Soo; Shin, Sun; Noh, Jun Hong; Cho, In Sun; Hong, Kug Sun

2014-04-01

Hierarchically organized nanostructures were fabricated by growing SnO2 nanoparticles on a fluorine-doped tin oxide/glass substrate via a laser ablation method. Cauliflower-like clusters consisting of agglomerated nanoparticles were deposited and aligned with respect to the substrate with a large internal surface area and open channels of pores. The morphological changes of SnO2 nanostructured films were investigated as a function of the oxygen working pressure in the range of 100-500 mTorr. A nanostructured scaffold prepared at an oxygen working pressure of 100 mTorr exhibited the best photoelectrochemical (PEC) performance. A Ti:Fe2O3-SnO2 nanostructured photoanode showed the photocurrent that was 34% larger than that of a Ti:Fe2O3 flat photoanode when the amount of Ti:Fe2O3 sensitizer was identical for the two photoanodes. The larger surface area and longer electron lifetime of the Ti:Fe2O3-SnO2 nanostructured photoanode explains its improved PEC performance.

On the physics of dispersive electron transport characteristics in SnO2 nanoparticle-based dye sensitized solar cells.

PubMed

Ashok, Aditya; Vijayaraghavan, S N; Unni, Gautam E; Nair, Shantikumar V; Shanmugam, Mariyappan

2018-04-27

The present study elucidates dispersive electron transport mediated by surface states in tin oxide (SnO 2 ) nanoparticle-based dye sensitized solar cells (DSSCs). Transmission electron microscopic studies on SnO 2 show a distribution of ∼10 nm particles exhibiting (111) crystal planes with inter-planar spacing of 0.28 nm. The dispersive transport, experienced by photo-generated charge carriers in the bulk of SnO 2 , is observed to be imposed by trapping and de-trapping processes via SnO 2 surface states present close to the band edge. The DSSC exhibits 50% difference in performance observed between the forward (4%) and reverse (6%) scans due to the dispersive transport characteristics of the charge carriers in the bulk of the SnO 2 . The photo-generated charge carriers are captured and released by the SnO 2 surface states that are close to the conduction band-edge resulting in a very significant variation; this is confirmed by the hysteresis observed in the forward and reverse scan current-voltage measurements under AM1.5 illumination. The hysteresis behavior assures that the charge carriers are accumulated in the bulk of electron acceptor due to the trapping, and released by de-trapping mediated by surface states observed during the forward and reverse scan measurements.

On the physics of dispersive electron transport characteristics in SnO2 nanoparticle-based dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Ashok, Aditya; Vijayaraghavan, S. N.; Unni, Gautam E.; Nair, Shantikumar V.; Shanmugam, Mariyappan

2018-04-01

The present study elucidates dispersive electron transport mediated by surface states in tin oxide (SnO2) nanoparticle-based dye sensitized solar cells (DSSCs). Transmission electron microscopic studies on SnO2 show a distribution of ˜10 nm particles exhibiting (111) crystal planes with inter-planar spacing of 0.28 nm. The dispersive transport, experienced by photo-generated charge carriers in the bulk of SnO2, is observed to be imposed by trapping and de-trapping processes via SnO2 surface states present close to the band edge. The DSSC exhibits 50% difference in performance observed between the forward (4%) and reverse (6%) scans due to the dispersive transport characteristics of the charge carriers in the bulk of the SnO2. The photo-generated charge carriers are captured and released by the SnO2 surface states that are close to the conduction band-edge resulting in a very significant variation; this is confirmed by the hysteresis observed in the forward and reverse scan current-voltage measurements under AM1.5 illumination. The hysteresis behavior assures that the charge carriers are accumulated in the bulk of electron acceptor due to the trapping, and released by de-trapping mediated by surface states observed during the forward and reverse scan measurements.

SnO2 quantum dots with rapid butane detection at lower ppm-level

NASA Astrophysics Data System (ADS)

Cai, Pan; Dong, Chengjun; Jiang, Ming; Shen, Yuanyuan; Tao, You; Wang, Yude

2018-04-01

SnO2 quantum dots (QDs) were successfully synthesized by a facile approach employing benzyl alcohol and ammonium hydroxide at lower temperature of 130 °C. It is revealed that the SnO2 QDs is about 3 nm in size to form clusters. The gas sensor based on SnO2 QDs shows a high potential for detecting low-ppm-level butane at 400 °C, exhibiting a high sensitivity, short response and rapid recovery time, and effective selectivity. The sensing mechanism is understood in terms of adsorbed oxygen species. Significantly, the excellent sensing performance is attributed to the smaller size of SnO2 and larger surface area (204.85 m2/g).

Probing the Failure Mechanism of SnO2 Nanowires for Sodium-ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, Meng; Kushima, Akihiro; Shao, Yuyan

2013-09-30

Non-lithium metals such as sodium have attracted wide attention as a potential charge carrying ion for rechargeable batteries, performing the same role as lithium in lithium- ion batteries. As sodium and lithium have the same +1 charge, it is assumed that what has been learnt about the operation of lithium ion batteries can be transferred directly to sodium batteries. Using in-situ TEM, in combination with DFT calculations, we probed the structural and chemical evolution of SnO2 nanowire anodes in Na-ion batteries and compared them quantitatively with results from Li-ion batteries [Science 330 (2010) 1515]. Upon Na insertion into SnO2, amore » displacement reaction occurs, leading to the formation of amorphous NaxSn nanoparticles covered by crystalline Na2O shell. With further Na insertion, the NaxSn core crystallized into Na15Sn4 (x=3.75). Upon extraction of Na (desodiation), the NaxSn core transforms to Sn nanoparticles. Associated with a volume shrinkage, nanopores appear and metallic Sn particles are confined in hollow shells of Na2O, mimicking a peapod structure. These pores greatly increase electrical impedance, therefore naturally accounting for the poor cyclability of SnO2. DFT calculations indicate that Na+ diffuses 30 times slower than Li+ in SnO2, in agreement with in-situ TEM measurement. Insertion of Na can chemo-mechanically soften the reaction product to greater extent than in lithiation. Therefore, in contrast to the lithiation of SnO2, no dislocation plasticity was seen ahead of the sodiation front. This direct comparison of the results from Na and Li highlights the critical role of ionic size and electronic structure of different ionic species on the charge/discharge rate and failure mechanisms in these batteries.« less

Strain effect in epitaxial VO2 thin films grown on sapphire substrates using SnO2 buffer layers

NASA Astrophysics Data System (ADS)

Kim, Heungsoo; Bingham, Nicholas S.; Charipar, Nicholas A.; Piqué, Alberto

2017-10-01

Epitaxial VO2/SnO2 thin film heterostructures were deposited on m-cut sapphire substrates via pulsed laser deposition. By adjusting SnO2 (150 nm) growth conditions, we are able to control the interfacial strain between the VO2 film and SnO2 buffer layer such that the semiconductor-to-metal transition temperature (TC) of VO2 films can be tuned without diminishing the magnitude of the transition. It is shown that in-plane tensile strain and out-of-plane compressive strain of the VO2 film leads to a decrease of Tc. Interestingly, VO2 films on SnO2 buffer layers exhibit a structural phase transition from tetragonal-like VO2 to tetragonal-VO2 during the semiconductor-to-metal transition. These results suggest that the strain generated by SnO2 buffer provides an effective way for tuning the TC of VO2 films.

Dopant controlled photoinduced hydrophilicity and photocatalytic activity of SnO2 thin films

NASA Astrophysics Data System (ADS)

Talinungsang; Dhar Purkayastha, Debarun; Krishna, M. Ghanashyam

2018-07-01

The influence of Fe and Ni (1 wt.%) doping on the wettability and photocatalytic activity of sol-gel derived SnO2 films is reported. X-ray diffraction studies revealed the presence of tetragonal phase for both pure and doped SnO2 thin films. The crystallite size was of the order of 8 nm indicating the nanocrystalline nature of the films. The pure SnO2 films which were hydrophilic with a contact angle of 11.8° showed increase in contact angle with doping (38.7° for Fe and 48.6° for Ni). This is accompanied by decrease in surface energy and root mean square roughness, with doping of SnO2 film. In order to further increase the water contact angle, the film surfaces were modified using a layer of stearic acid. As a consequence, the water contact angles increased to 108°, 110° and 111° for the pure, Fe and Ni doped SnO2 films respectively, rendering them hydrophobic. Significantly, the unmodified surfaces that did not exhibit any change under UV irradiation showed photoinduced hydrophilicity on modification with stearic acid. There was a red-shift in the optical band gap of SnO2 films from 3.8 to 3.5 eV with doping, indicating the possibility of dopant controlled photocatalytic activity. This was confirmed by observing the photocatalytic degradation of an aqueous solution of methylene blue under UV irradiation. There was, indeed, significant improvement in the photocatalytic efficiency of the metal doped SnO2 thin film in comparison to undoped film. The current work, thus, demonstrates a simple method to chemically engineer the wettability and photocatalytic activity of SnO2 thin film surfaces.

Data of chemical analysis and electrical properties of SnO2-TiO2 composite nanofibers.

PubMed

Bakr, Zinab H; Wali, Qamar; Ismail, Jamil; Elumalai, Naveen Kumar; Uddin, Ashraf; Jose, Rajan

2018-06-01

In this data article, we provide energy dispersive X-ray spectroscopy (EDX) spectra of the electrospun composite (SnO 2 -TiO 2 ) nanowires with the elemental values measured in atomic and weight%. The linear sweep voltammetry data of composite and its component nanofibers are provided. The data collected in this article is directly related to our research article "Synergistic combination of electronic and electrical properties of SnO 2 and TiO 2 in a single SnO 2 -TiO 2 composite nanowire for dye-sensitized solar cells" [1].

Ultrafast Recombination Dynamics in Dye-Sensitized SnO2/TiO2 Core/Shell Films.

PubMed

Gish, Melissa K; Lapides, Alexander M; Brennaman, M Kyle; Templeton, Joseph L; Meyer, Thomas J; Papanikolas, John M

2016-12-15

Interfacial dynamics are investigated in SnO 2 /TiO 2 core/shell films derivatized with a Ru(II)-polypyridyl chromophore ([Ru II (bpy) 2 (4,4'-(PO 3 H 2 ) 2 bpy)] 2+ , RuP) using transient absorption methods. Electron injection from the chromophore into the TiO 2 shell occurs within a few picoseconds after photoexcitation. Loss of the oxidized dye through recombination occurs across time scales spanning 10 orders of magnitude. The majority (60%) of charge recombination events occur shortly after injection (τ = 220 ps), while a small fraction (≤20%) of the oxidized chromophores persists for milliseconds. The lifetime of long-lived charge-separated states (CSS) depends exponentially on shell thickness, suggesting that the injected electrons reside in the SnO 2 core and must tunnel through the TiO 2 shell to recombine with oxidized dyes. While the core/shell architecture extends the lifetime in a small fraction of the CSS, making water oxidation possible, the subnanosecond recombination process has profound implications for the overall efficiencies of dye-sensitized photoelectrosynthesis cells (DSPECs).

Photocatalytic degradation of diclofenac using TiO2-SnO2 mixed oxide catalysts.

PubMed

Mugunthan, E; Saidutta, M B; Jagadeeshbabu, P E

2017-12-26

The complex nature of diclofenac limits its biological degradation, posing a serious threat to aquatic organisms. Our present work aims to eliminate diclofenac from wastewater through photocatalytic degradation using TiO 2 -SnO 2 mixed-oxide catalysts under various operating conditions such as catalyst loading, initial diclofenac concentration and initial pH. Different molar ratios of Ti-Sn (1:1, 5:1, 10:1, 20:1 and 30:1) were prepared by the hydrothermal method and were characterized. The results indicated that addition of Sn in small quantity enhances the catalytic activity of TiO 2 . Energy Band gap of the TiO 2 -SnO 2 catalysts was found to increase with an increase in Tin content. TiO 2 -SnO 2 catalyst with a molar ratio of 20:1 was found to be the most effective when compared to other catalysts. The results suggested that initial drug concentration of 20 mg/L, catalyst loading of 0.8 g/L and pH 5 were the optimum operating conditions for complete degradation of diclofenac. Also, the TiO 2 -SnO 2 catalyst was effective in complete mineralization of diclofenac with a maximum total organic carbon removal of 90% achieved under ultraviolet irradiation. The repeatability and stability results showed that the TiO 2 -SnO 2 catalyst exhibited an excellent repeatability and better stability over the repeated reaction cycles. The photocatalytic degradation of diclofenac resulted in several photoproducts, which were identified through LC-MS.

Gas-sensing enhancement methods for hydrothermal synthesized SnO2-based sensors

NASA Astrophysics Data System (ADS)

Zhao, Yalei; Zhang, Wenlong; Yang, Bin; Liu, Jingquan; Chen, Xiang; Wang, Xiaolin; Yang, Chunsheng

2017-11-01

Gas sensing for hydrothermal synthesized SnO2-based gas sensors can be enhanced in three ways: structural improvement, composition optimization, and processing improvement. There have been zero-dimensional, one-dimensional, and three-dimensional structures reported in the literature. Controllable synthesis of different structures has been deployed to increase specific surface area. Change of composition would intensively tailor the SnO2 structure, which affected the gas-sensing performance. Furthermore, doping and compounding methods have been adopted to promote gas-sensing performance by adjusting surface conditions of SnO2 crystals and constructing heterojunctions. As for processing area, it is very important to find the optimal reaction time and temperature. In this paper, a gas-solid reaction rate constant was proposed to evaluate gas-sensing properties and find an excellent hydrothermal synthesized SnO2-based gas sensor.

Metal-to-insulator transition induced by UV illumination in a single SnO2 nanobelt

NASA Astrophysics Data System (ADS)

Viana, E. R.; Ribeiro, G. M.; de Oliveira, A. G.; González, J. C.

2017-11-01

An individual tin oxide (SnO2) nanobelt was connected in a back-gate field-effect transistor configuration and the conductivity of the nanobelt was measured at different temperatures from 400 K to 4 K, in darkness and under UV illumination. In darkness, the SnO2 nanobelts showed semiconductor behavior for the whole temperature range measured. However, when subjected to UV illumination the photoinduced carriers were high enough to lead to a metal-to-insulator transition (MIT), near room temperature, at T MIT = 240 K. By measuring the current versus gate voltage curves, and considering the electrostatic properties of a non-ideal conductor, for the SnO2 nanobelt on top of a gate-oxide substrate, we estimated the capacitance per unit length, the mobility and the density of carriers. In darkness, the density was estimated to be 5-10 × 1018 cm-3, in agreement with our previously reported result (Phys. Status Solid. RRL 6, 262-4 (2012)). However, under UV illumination the density of carriers was estimated to be 0.2-3.8 × 1019 cm-3 near T MIT, which exceeded the critical Mott density estimated to be 2.8 × 1019 cm-3 above 240 K. These results showed that the electrical properties of the SnO2 nanobelts can be drastically modified and easily tuned from semiconducting to metallic states as a function of temperature and light.

Preparation of Ru-doped SnO2-supported Pt catalysts and their electrocatalytic properties for methanol oxidation.

PubMed

Pang, H L; Zhang, X H; Zhong, X X; Liu, B; Wei, X G; Kuang, Y F; Chen, J H

2008-03-01

Ru-doped SnO2 nanoparticles were prepared by chemical precipitation and calcinations at 823 K. Due to high stability in diluted acidic solution, Ru-doped SnO2 nanoparticles were selected as the catalyst support and second catalyst for methanol electrooxidation. The micrograph, elemental composition, and structure of the Ru-doped SnO2 nanoparticles were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction, respectively. The electrocatalytic properties of the Ru-doped SnO2-supported Pt catalyst (Pt/Ru-doped SnO2) for methanol oxidation have been investigated by cyclic voltammetry. Under the same loading mass of Pt, the Pt/Ru-doped SnO2 catalyst shows better electrocatalytic performance than the Pt/SnO2 catalyst and the best atomic ratio of Ru to Sn in Ru-doped SnO2 is 1/75. Additionally, the Pt/Ru-doped SnO2 catalyst possesses good long-term cycle stability.

Characterization and properties of TiO2-SnO2 nanocomposites, obtained by hydrolysis method

NASA Astrophysics Data System (ADS)

Kutuzova, Anastasiya S.; Dontsova, Tetiana A.

2018-04-01

The paper deals with the process of TiO2-SnO2 nanocomposites synthesis utilizing simple hydrolysis method with further calcination for photocatalytic applications. The obtained nanopowders contain 100, 90, 75, 65 and 25 wt% of TiO2. The synthesized nanocomposite samples were analyzed by X-ray diffraction method, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and N2 adsorption-desorption method. The correlation between structure and morphology of the obtained nanocrystalline composite powders and their sorption and photocatalytic activity towards methylene blue degradation was established. It was found that the presence of SnO2 in the nanocomposites stabilizes the anatase phase of TiO2. Furthermore, sorption and photocatalytic properties of the obtained composites are significantly influenced not only by specific surface area, but also by pore size distribution and mesopore volume of the samples. In our opinion, the results obtained in this study have shown that the TiO2-SnO2 composites with SnO2 content that does not exceed 10% are promising for photocatalytic applications.

Synthesis of nanodimensional orthorhombic SnO2 thin films

NASA Astrophysics Data System (ADS)

Kondkar, V.; Rukade, D.; Kanjilal, D.; Bhattacharyya, V.

2018-04-01

Amorphous thin films of SnO2 are irradiated by swift heavy ions at two different fluences. Unirradiated as well as irradiated films are characterized by glancing angle X-ray diffraction (GAXRD), UV-Vis spectroscopy and atomic force microscopy (AFM). GAXRD study reveals formation of orthorhombic nanophases of SnO2. Nanophase formation is also confirmed by the quantum size effect manifested by blue shift in terms of increase in band gap energy. The size and shape of the irradiation induced surface structures depend on ion fluence.

Nanocrystalline SnO2:F thin films for liquid petroleum gas sensors.

PubMed

Chaisitsak, Sutichai

2011-01-01

This paper reports the improvement in the sensing performance of nanocrystalline SnO(2)-based liquid petroleum gas (LPG) sensors by doping with fluorine (F). Un-doped and F-doped tin oxide films were prepared on glass substrates by the dip-coating technique using a layer-by-layer deposition cycle (alternating between dip-coating a thin layer followed by a drying in air after each new layer). The results showed that this technique is superior to the conventional technique for both improving the film thickness uniformity and film transparency. The effect of F concentration on the structural, surface morphological and LPG sensing properties of the SnO(2) films was investigated. Atomic Force Microscopy (AFM) and X-ray diffraction pattern measurements showed that the obtained thin films are nanocrystalline SnO(2) with nanoscale-textured surfaces. Gas sensing characteristics (sensor response and response/recovery time) of the SnO(2):F sensors based on a planar interdigital structure were investigated at different operating temperatures and at different LPG concentrations. The addition of fluorine to SnO(2) was found to be advantageous for efficient detection of LPG gases, e.g., F-doped sensors are more stable at a low operating temperature (300 °C) with higher sensor response and faster response/recovery time, compared to un-doped sensor materials. The sensors based on SnO(2):F films could detect LPG even at a low level of 25% LEL, showing the possibility of using this transparent material for LPG leak detection.

Nanocrystalline SnO2:F Thin Films for Liquid Petroleum Gas Sensors

PubMed Central

Chaisitsak, Sutichai

2011-01-01

This paper reports the improvement in the sensing performance of nanocrystalline SnO2-based liquid petroleum gas (LPG) sensors by doping with fluorine (F). Un-doped and F-doped tin oxide films were prepared on glass substrates by the dip-coating technique using a layer-by-layer deposition cycle (alternating between dip-coating a thin layer followed by a drying in air after each new layer). The results showed that this technique is superior to the conventional technique for both improving the film thickness uniformity and film transparency. The effect of F concentration on the structural, surface morphological and LPG sensing properties of the SnO2 films was investigated. Atomic Force Microscopy (AFM) and X-ray diffraction pattern measurements showed that the obtained thin films are nanocrystalline SnO2 with nanoscale-textured surfaces. Gas sensing characteristics (sensor response and response/recovery time) of the SnO2:F sensors based on a planar interdigital structure were investigated at different operating temperatures and at different LPG concentrations. The addition of fluorine to SnO2 was found to be advantageous for efficient detection of LPG gases, e.g., F-doped sensors are more stable at a low operating temperature (300 °C) with higher sensor response and faster response/recovery time, compared to un-doped sensor materials. The sensors based on SnO2:F films could detect LPG even at a low level of 25% LEL, showing the possibility of using this transparent material for LPG leak detection. PMID:22164007

[Ski and SnoN: antagonistic proteins of TGFbeta signaling].

PubMed

Vignais, M L

2000-02-01

Ski and SnoN are two proto-oncogenes that, at high cellular concentrations, are associated with tumors. Up to now, apart the fact that SnoN and Ski were known to bind to DNA indirectly, very little was known about the mechanism which enables these factors to induce tumorigenesis. We know now that SnoN and Ski interact with the SMAD proteins which are mediators of TGFbeta signaling. These SMADs enable recruitment to target gene promoters of SnoN and Ski as well as the histone deacetylase activity which is associated with them. Whereas physiologic concentrations of SnoN and Ski allow a feedback regulation of TGFbeta signaling, deregulation of SnoN or Ski expression leads to total inhibition of TGFbeta signaling and of the tumor suppressors Smad2 and Smad4, which can explain the role of SnoN and Ski as oncogenes.

A novel snowflake-like SnO2 hierarchical architecture with superior gas sensing properties

NASA Astrophysics Data System (ADS)

Li, Yanqiong

2018-02-01

Snowflake-like SnO2 hierarchical architecture has been synthesized via a facile hydrothermal method and followed by calcination. The SnO2 hierarchical structures are assembled with thin nanoflakes blocks, which look like snowflake shape. A possible mechanism for the formation of the SnO2 hierarchical structures is speculated. Moreover, gas sensing tests show that the sensor based on snowflake-like SnO2 architectures exhibited excellent gas sensing properties. The enhancement may be attributed to its unique structures, in which the porous feature on the snowflake surface could further increase the active surface area of the materials and provide facile pathways for the target gas.

Fabrication of textured SnO2 transparent conductive films using self-assembled Sn nanospheres

NASA Astrophysics Data System (ADS)

Fukumoto, Michitaka; Nakao, Shoichiro; Hirose, Yasushi; Hasegawa, Tetsuya

2018-06-01

We present a novel method to fabricate textured surfaces on transparent conductive SnO2 films by processing substrates through a bottom-up technique with potential for industrially scalable production. The substrate processing consists of three steps: deposition of precursor Sn films on glass substrates, formation of a self-assembled Sn nanosphere layer with reductive annealing, and conversion of Sn to SnO2 by oxidative annealing. Ta-doped SnO2 films conformally deposited on the self-assembled nanospherical SnO2 templates exhibited attractive optical and electrical properties, namely, enhanced haze values and low sheet resistances, for applications as transparent electrodes in photovoltaics.

SnO2@C@VO2 Composite Hollow Nanospheres as an Anode Material for Lithium-Ion Batteries.

PubMed

Guo, Wenbin; Wang, Yong; Li, Qingyuan; Wang, Dongxia; Zhang, Fanchao; Yang, Yiqing; Yu, Yang

2018-05-02

Porous SnO 2 @C@VO 2 composite hollow nanospheres were ingeniously constructed through the combination of layer-by-layer deposition and redox reaction. Moreover, to optimize the electrochemical properties, SnO 2 @C@VO 2 composite hollow nanospheres with different contents of the external VO 2 were also studied. On the one hand, the elastic and conductive carbon as interlayer in the SnO 2 @C@VO 2 composite can not only buffer the huge volume variation during repetitive cycling but also effectively improve electronic conductivity and enhance the utilizing rate of SnO 2 and VO 2 with high theoretical capacity. On the other hand, hollow nanostructures of the composite can be consolidated by the multilayered nanocomponents, resulting in outstanding cyclic stability. In virtue of the above synergetic contribution from individual components, SnO 2 @C@VO 2 composite hollow nanospheres exhibit a large initial discharge capacity (1305.6 mAhg -1 ) and outstanding cyclic stability (765.1 mAhg -1 after 100 cycles). This design of composite hollow nanospheres may be extended to the synthesis of other nanomaterials for electrochemical energy storage.

SnO2-gated AlGaN/GaN high electron mobility transistors based oxygen sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hung, S.T.; Chung, Chi-Jung; Chen, Chin Ching

2012-01-01

Hydrothermally grown SnO2 was integrated with AlGaN/GaN high electron mobility transistor (HEMT) sensor as the gate electrode for oxygen detection. The crystalline of the SnO2 was improved after annealing at 400 C. The grain growth kinetics of the SnO2 nanomaterials, together with the O2 gas sensing properties and sensing mechanism of the SnO2 gated HEMT sensors were investigated. Detection of 1% oxygen in nitrogen at 100 C was possible. A low operation temperature and low power consumption oxygen sensor can be achieved by combining the SnO2 films with the AlGaN/GaN HEMT structure

Excellent rate capability and cycling stability in Li+-conductive Li2SnO3-coated LiNi0.5Mn1.5O4 cathode materials for lithium-ion batteries.

PubMed

Mou, Jirong; Deng, Yunlong; Song, Zhicui; Zheng, Qiaoji; Lam, Kwok Ho; Lin, Dunmin

2018-05-22

High-voltage LiNi0.5Mn1.5O4 is a promising cathode candidate for lithium-ion batteries (LIBs) due to its considerable energy density and power density, but the material generally undergoes serious capacity fading caused by side reactions between the active material and organic electrolyte. In this work, Li+-conductive Li2SnO3 was coated on the surface of LiNi0.5Mn1.5O4 to protect the cathode against the attack of HF, mitigate the dissolution of Mn ions during cycling and improve the Li+ diffusion coefficient of the materials. Remarkable improvement in cycling stability and rate performance has been achieved in Li2SnO3-coated LiNi0.5Mn1.5O4. The 1.0 wt% Li2SnO3-coated LiNi0.5Mn1.5O4 cathode exhibits excellent cycling stability with a capacity retention of 88.2% after 150 cycles at 0.1 C and rate capability at high discharge rates of 5 C and 10 C, presenting discharge capacities of 119.5 and 112.2 mAh g-1, respectively. In particular, a significant improvement in cycling stability at 55 °C is obtained after the coating of 1.0 wt% Li2SnO3, giving a capacity retention of 86.8% after 150 cycles at 1 C and 55 °C. The present study provides a significant insight into the effective protection of Li-conductive coating materials for a high-voltage LiNi0.5Mn1.5O4 cathode material.

A novel approach for the synthesis of SnO2 nanoparticles and its application as a catalyst in the reduction and photodegradation of organic compounds.

PubMed

Bhattacharjee, Archita; Ahmaruzzaman, M; Sinha, Tanur

2015-02-05

Tin oxide (SnO2) nanoparticles of sizes ∼4.5, ∼10 and ∼30 nm were successfully synthesized by a simple chemical precipitation method using amino acid, glycine which acts as a complexing agent and surfactant, namely sodium dodecyl sulfate (SDS) as a stabilizing agent, at various calcination temperatures of 200, 400 and 600°C. This method resulted in the formation of spherical SnO2 nanoparticles and the size of the nanoparticles was found to be a factor of calcination temperature. The spherical SnO2 nanoparticles show a tetragonal rutile crystalline structure. A dramatic increase in band gap energy (3.8-4.21 eV) was observed with a decrease in grain size (30-4.5 nm) due to three dimensional quantum confinement effect shown by the synthesized SnO2 nanoparticles. SnO2 nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and fourier transformed infrared spectroscopy (FT-IR). The optical properties were investigated using UV-visible spectroscopy. These SnO2 nanoparticles were employed as catalyst for the reduction of p-nitro phenol to p-amino phenol in aqueous medium for the first time. The synthesized SnO2 nanoparticles act as an efficient photocatalyst in the degradation of methyl violet 6B dye under direct sunlight. For the first time, methyl violet 6B dye was degraded by SnO2 nanoparticles under direct sunlight. Copyright © 2014 Elsevier B.V. All rights reserved.

BiVO4/WO3/SnO2 Double-Heterojunction Photoanode with Enhanced Charge Separation and Visible-Transparency for Bias-Free Solar Water-Splitting with a Perovskite Solar Cell.

PubMed

Baek, Ji Hyun; Kim, Byeong Jo; Han, Gill Sang; Hwang, Sung Won; Kim, Dong Rip; Cho, In Sun; Jung, Hyun Suk

2017-01-18

Coupling dissimilar oxides in heterostructures allows the engineering of interfacial, optical, charge separation/transport and transfer properties of photoanodes for photoelectrochemical (PEC) water splitting. Here, we demonstrate a double-heterojunction concept based on a BiVO 4 /WO 3 /SnO 2 triple-layer planar heterojunction (TPH) photoanode, which shows simultaneous improvements in the charge transport (∼93% at 1.23 V vs RHE) and transmittance at longer wavelengths (>500 nm). The TPH photoanode was prepared by a facile solution method: a porous SnO 2 film was first deposited on a fluorine-doped tin oxide (FTO)/glass substrate followed by WO 3 deposition, leading to the formation of a double layer of dense WO 3 and a WO 3 /SnO 2 mixture at the bottom. Subsequently, a BiVO 4 nanoparticle film was deposited by spin coating. Importantly, the WO 3 /(WO 3 +SnO 2 ) composite bottom layer forms a disordered heterojunction, enabling intimate contact, lower interfacial resistance, and efficient charge transport/transfer. In addition, the top BiVO 4 /WO 3 heterojunction layer improves light absorption and charge separation. The resultant TPH photoanode shows greatly improved internal quantum efficiency (∼80%) and PEC water oxidation performance (∼3.1 mA/cm 2 at 1.23 V vs RHE) compared to the previously reported BiVO 4 /WO 3 photoanodes. The PEC performance was further improved by a reactive-ion etching treatment and CoO x electrocatalyst deposition. Finally, we demonstrated a bias-free and stable solar water-splitting by constructing a tandem PEC device with a perovskite solar cell (STH ∼3.5%).

Study on preparation of SnO2-TiO2/Nano-graphite composite anode and electro-catalytic degradation of ceftriaxone sodium.

PubMed

Guo, Xiaolei; Wan, Jiafeng; Yu, Xiujuan; Lin, Yuhui

2016-12-01

In order to improve the electro-catalytic activity and catalytic reaction rate of graphite-like material, Tin dioxide-Titanium dioxide/Nano-graphite (SnO 2 -TiO 2 /Nano-G) composite was synthesized by a sol-gel method and SnO 2 -TiO 2 /Nano-G electrode was prepared in hot-press approach. The composite was characterized by X-ray photoelectron spectroscopy, fourier transform infrared, Raman, N 2 adsorption-desorption, scanning electrons microscopy, transmission electron microscopy and X-ray diffraction. The electrochemical performance of the SnO 2 -TiO 2 /Nano-G anode electrode was investigated via cyclic voltammetry and electrochemical impedance spectroscopy. The electro-catalytic performance was evaluated by the degradation of ceftriaxone sodium and the yield of ·OH radicals in the reaction system. The results demonstrated that TiO 2 , SnO 2 and Nano-G were composited successfully, and TiO 2 and SnO 2 particles dispersed on the surface and interlamination of the Nano-G uniformly. The specific surface area of SnO 2 modified anode was higher than that of TiO 2 /Nano-G anode and the degradation rate of ceftriaxone sodium within 120 min on SnO 2 -TiO 2 /Nano-G electrode was 98.7% at applied bias of 2.0 V. The highly efficient electro-chemical property of SnO 2 -TiO 2 /Nano-G electrode was attributed to the admirable conductive property of the Nano-G and SnO 2 -TiO 2 /Nano-G electrode. Moreover, the contribution of reactive species ·OH was detected, indicating the considerable electro-catalytic activity of SnO 2 -TiO 2 /Nano-G electrode. Copyright © 2016 Elsevier Ltd. All rights reserved.

High-pressure phases transitions in SnO2 to 117 GPa: Implications for silica

NASA Astrophysics Data System (ADS)

Shieh, S. R.; Kubo, A.; Duffy, T. S.; Prakapenka, V. B.; Shen, G.

2005-12-01

Cassiterite (SnO2) is regarded to be a good analog material for silica as both SnO2 and SiO2 are group IV-B metal dioxides. The high-pressure behavior of SnO2 has been the subject of many previous investigations extending up to 49 GPa and in addition to the rutile structure, three high-pressure phases, CaCl2-type, α-PbO2-type, and pyrite-type were observed. Better knowledge of high-pressure phases of SnO2 will be useful to understand the behavior of silica at deep mantle conditions. In addition, high-pressure metal dioxide phases may qualify as superhard solids. Our study will also provide insights into interpretation of shock compression data. Pure natural cassiterite (SnO2) powder was compressed in a diamond anvil cell using an argon medium. Pressure was determined from the equation of state of platinum. In situ monochromatic x-ray diffraction at high pressure was carried out at the GSECARS, Advanced Photon Source. High temperatures were achieved using double-sided laser heating . Three heating cycles were conducted with total heating times up to 30 minutes. Our diffraction results on SnO2 demonstrate the existence of four phase transitions to 117 GPa. The observed sequence of high-pressure phases for SnO2 is rutile-type, CaCl2-type, pyrite-type, ZrO2 orthorhombic phase I (Pbca), cotunnite-type. Our observations of the first three phases are generally in agreement with earlier studies. The orthorhombic phase I and cotunnite-type structures were observed in SnO2 for the first time. The Pbca phase is found at 50-74 GPa during room-temperature compression. The cotunnite-type structure was synthesized when SnO2 was heated at 74 GPa and 1200 K. The cotunnite-type form was observed during compression between 54-117 GPa. Fitting the pressure-volume data for the high-pressure phases to the second-order Birch-Murnaghan equation of state yields a bulk modulus of 259(26) GPa for the Pbca phase and 417(7) GPa for the cotunnite-type phase. Rietveld profile refinements were

A comparative study of the magnetization in transition metal ion doped CeO2, TiO2 and SnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Apostolov, A. T.; Apostolova, I. N.; Wesselinowa, J. M.

2018-05-01

Using the microscopic s-d model taking into account anharmonic spin-phonon interactions we have studied the magnetic properties of Co and Cu ion doped CeO2 and TiO2 nanoparticles and compared them with those of SnO2. By Co-doping there is a maximum in the magnetization M(x) curve for all nanoparticles observed in the most transition metal doped ones. The s-d interaction plays an important role by the decrease of M at higher dopant concentration. We have discussed the magnetization in dependence of different model parameters. By small Cu-ion doping there are some differences. In CeO2M decreases with the Cu-concentration, whereas in TiO2 and SnO2M increases. For higher Cu dopant concentrations M(X) decreases in TiO2 nanoparticles. We obtain room temperature ferromagnetism also in Zn doped CeO2, TiO2 and SnO2 nanoparticles, i.e. in non-transition metal ion doped ones. The different behavior of M in Co and Cu doped nanoparticles is due to a combination effect of multivalent metal ions, oxygen vacancies, different radius of cation dopants, connection between lattice and magnetism, as well as competition between the s-d and d-d ferromagnetic or antiferromagnetic interactions.

In situ synthesized SnO2 nanorod/reduced graphene oxide low-dimensional structure for enhanced lithium storage

NASA Astrophysics Data System (ADS)

Zhang, Wei; Xiao, Xuezhang; Zhang, Yiwen; Li, Junpeng; Zhong, Jiayi; Li, Meng; Fan, Xiulin; Wang, Chuntao; Chen, Lixin

2018-03-01

A unique SnO2 nanorod (NR)/reduced graphene oxide (RGO) composite morphology has been synthesized using the in situ hydrothermal method, for use as an anode material in lithium-ion batteries. The SnO2 NR adhering to the RGO exhibits a length of 250-400 nm and a diameter of 60-80 nm without any obvious aggregation. The initial discharge/charge capacities of the SnO2 NR/RGO composite are 1761.3 mAh g-1 and 1233.1 mAh g-1, with a coulombic efficiency (CE) of 70% under a current density of 200 mA g-1, and a final capacity of 1101 mAh g-1 after 50 cycles. The rate capability of the SnO2 NR/RGO is also improved compared to that of bare SnO2 NR. The superior electrochemical performance is ascribed to the special morphology of the SnO2 NRs—which plays a role in shorting the transmission path—and the sheet-like 2D graphene, which prevents the agglomeration of SnO2 and enhances conductivity during the electrochemical reaction of SnO2 NR/RGO.

Chip-to-chip SnO2 nanowire network sensors for room temperature H2 detection

NASA Astrophysics Data System (ADS)

Köck, A.; Brunet, E.; Mutinati, G. C.; Maier, T.; Steinhauer, S.

2012-06-01

The employment of nanowires is a very powerful strategy to improve gas sensor performance. We demonstrate a gas sensor device, which is based on silicon chip-to-chip synthesis of ultralong tin oxide (SnO2) nanowires. The sensor device employs an interconnected SnO2 nanowire network configuration, which exhibits a huge surface-to-volume ratio and provides full access of the target gas to the nanowires. The chip-to-chip SnO2 nanowire device is able to detect a H2 concentration of only 20 ppm in synthetic air with ~ 60% relative humidity at room temperature. At an operating temperature of 300°C a concentration of 50 ppm H2 results in a sensitivity of 5%. At this elevated temperature the sensor shows a linear response in a concentration range between 10 ppm and 100 ppm H2. The SnO2-nanowire fabrication procedure based on spray pyrolysis and subsequent annealing is performed at atmospheric pressure, requires no vacuum and allows upscale of the substrate to a wafer size. 3D-integration with CMOS chips is proposed as viable way for practical realization of smart nanowire based gas sensor devices for the consumer market.

Synthesis and characterisations of SnO2 nanorods via low temperature hydrothermal method

NASA Astrophysics Data System (ADS)

Inderan, Vicinisvarri; Lim, Shin Ye; Ong, Teng Sian; Bastien, Samuel; Braidy, Nadi; Lee, Hooi Ling

2015-12-01

In the present study, tin oxide (SnO2) nanorods were successfully synthesized through hydrothermal treatment at a relatively low temperature (180 °C) using various concentrations of metal precursor, SnCl4·5H2O (0.04 M-0.16 M) in a mixed solution of ethanol and water before bringing the pH to 13 by adding 6 M NaOH. The effect of concentration on the morphology and structure of SnO2 were comprehensively studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis) and Fourier Transform Infrared (FTIR). It was found that increasing the concentration of tin precursor from 0.04 M to 0.16 M leads to a complete conversion from nanospheres to nanoplates and finally to nanorods. The SEM results confirmed that SnO2 nanorods are obtained for concentrations up to 0.12 M. At synthesis condition of 0.12 M, SnCl4·5H2O and pH 13, single rutile nanorods with preferential growth in the [002] direction were obtained. It was found that the diameter of nanorods formed at 0.12 M is similar to that of nanoplates formed at 0.08 M (20 nm), which suggests that spear-shaped nanorods might have originated from the primary nanoparticles (the particles grown in lower concentration during hydrothermal treatment). Possible reaction mechanisms are proposed to explain the observed morphologies.

Phylogenetic distribution of plant snoRNA families.

PubMed

Patra Bhattacharya, Deblina; Canzler, Sebastian; Kehr, Stephanie; Hertel, Jana; Grosse, Ivo; Stadler, Peter F

2016-11-24

Small nucleolar RNAs (snoRNAs) are one of the most ancient families amongst non-protein-coding RNAs. They are ubiquitous in Archaea and Eukarya but absent in bacteria. Their main function is to target chemical modifications of ribosomal RNAs. They fall into two classes, box C/D snoRNAs and box H/ACA snoRNAs, which are clearly distinguished by conserved sequence motifs and the type of chemical modification that they govern. Similarly to microRNAs, snoRNAs appear in distinct families of homologs that affect homologous targets. In animals, snoRNAs and their evolution have been studied in much detail. In plants, however, their evolution has attracted comparably little attention. In order to chart the phylogenetic distribution of individual snoRNA families in plants, we applied a sophisticated approach for identifying homologs of known plant snoRNAs across the plant kingdom. In response to the relatively fast evolution of snoRNAs, information on conserved sequence boxes, target sequences, and secondary structure is combined to identify additional snoRNAs. We identified 296 families of snoRNAs in 24 species and traced their evolution throughout the plant kingdom. Many of the plant snoRNA families comprise paralogs. We also found that targets are well-conserved for most snoRNA families. The sequence conservation of snoRNAs is sufficient to establish homologies between phyla. The degree of this conservation tapers off, however, between land plants and algae. Plant snoRNAs are frequently organized in highly conserved spatial clusters. As a resource for further investigations we provide carefully curated and annotated alignments for each snoRNA family under investigation.

Facile fabrication of hollow mesosphere of crystalline SnO2 nanoparticles and synthesis of SnO2@SWCNTs@Reduced Graphene Oxide nanocomposite as efficient Pt-Free counter electrode for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Khan, Muhammad Wasim; Yao, Jixin; Zhang, Kang; Zuo, Xueqin; Yang, Qun; Tang, Huaibao; Ur Rehman, Khalid Mehmood; Li, Guang; Wu, Mingzai; Zhu, Kerong; Zhang, Haijun

2018-06-01

In this research, SnO2@SWCNTs@Reduced Graphene Oxide based nanocomposite was synthesized by a one step hydrothermal method and reported new cost effective platinum-free counter-electrodes (CEs) in dye-sensitized solar cells (DSSCs). The CEs were formed by using the nanocomposites with the help of a pipette using a doctor-blade technique. The efficiency of this nanocomposite revealed significant elctrocatalytic properties upon falling the triiodide, possessing to synergistic effect of SnO2 nano particles and improved conductivity when SWCNTs dispersed on graphene sheet. Therefore, the power conversion efficiency (PCE) of prepared SnO2@SWCNTs@RGO nanocomposite CE attained of (6.1%) in DSSCs which is equivalent to the value (6.2%) which attained to the value (6.2%) with pure Pt CE as a reference. SnO2@SWCNTs@RGO nanocomposite CEs give more stable catalytic activities for triiodide reduction than SnO2 and SWCNTs CEs in the cyclic voltammetry (CV) analysis. Furthermore, to the subsistence of graphene oxide, the nanocomposite acquired both higher stability and efficiency in the nanocomposite.

Highly Efficient Gas Sensor Using a Hollow SnO2 Microfiber for Triethylamine Detection.

PubMed

Zou, Yihui; Chen, Shuai; Sun, Jin; Liu, Jingquan; Che, Yanke; Liu, Xianghong; Zhang, Jun; Yang, Dongjiang

2017-07-28

Triethylamine (TEA) gas sensors having excellent response and selectivity are in great demand to monitor the real environment. In this work, we have successfully prepared a hollow SnO 2 microfiber by a unique sustainable biomass conversion strategy and shown that the microfiber can be used in a high-performance gas sensor. The sensor based on the hollow SnO 2 microfiber shows a quick response/recovery toward triethylamine. The response of the hollow SnO 2 microfiber is up to 49.5 when the concentration of TEA gas is 100 ppm. The limit of detection is as low as 2 ppm. Furthermore, the sensor has a relatively low optimal operation temperature of 270 °C, which is lower than those of many other reported sensors. The excellent sensing properties are largely attributed to the high sensitivity provided by SnO 2 and the good permeability and conductivity of the one-dimensional hollow structure. Thus, the hollow SnO 2 microfiber using sustainable biomass as a template is a significant strategy for a unique TEA gas sensor.

Carbon-coated SnO2 nanotubes: template-engaged synthesis and their application in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wu, Ping; Du, Ning; Zhang, Hui; Yu, Jingxue; Qi, Yue; Yang, Deren

2011-02-01

This paper reports the synthesis of carbon-coated SnO2 (SnO2-C) nanotubes through a simple glucose hydrothermal and subsequent carbonization approach by using Sn nanorods as sacrificial templates. The as-synthesized SnO2-C nanotubes have been applied as anode materials for lithium-ion batteries, which exhibit improved cyclic performance compared to pure SnO2 nanotubes. The hollow nanostructure, together with the carbon matrix which has good buffering effect and high electronic conductivity, can be responsible for the improved cyclic performance.

Spectral and ion emission features of laser-produced Sn and SnO2 plasmas

NASA Astrophysics Data System (ADS)

Hui, Lan; Xin-Bing, Wang; Du-Luo, Zuo

2016-03-01

We have made a detailed comparison of the atomic and ionic debris, as well as the emission features of Sn and SnO2 plasmas under identical experimental conditions. Planar slabs of pure metal Sn and ceramic SnO2 are irradiated with 1.06 μm, 8 ns Nd:YAG laser pulses. Fast photography employing an intensified charge coupled device (ICCD), optical emission spectroscopy (OES), and optical time of flight emission spectroscopy are used as diagnostic tools. Our results show that the Sn plasma provides a higher extreme ultraviolet (EUV) conversion efficiency (CE) than the SnO2 plasma. However, the kinetic energies of Sn ions are relatively low compared with those of SnO2. OES studies show that the Sn plasma parameters (electron temperature and density) are lower compared to those of the SnO2 plasma. Furthermore, we also give the effects of the vacuum degree and the laser pulse energy on the plasma parameters. Project supported by the National Natural Science Foundation of China (Grant No. 11304235) and the Director Fund of WNLO, China.

A Facile Large-Scale Synthesis of Porous SnO2 by Bronze for Superior Lithium Storage and Gas Sensing Properties Through a Wet Chemical Reaction Strategy

NASA Astrophysics Data System (ADS)

Yue, Lu; Ge, Jingjing; Luo, Gaixia; Bian, Kaiting; Yin, Chao; Guan, Rongfeng; Zhang, Wenhui; Zhou, Zheng; Wang, Kaixin; Guo, Xiufeng

2018-03-01

A facile approach to prepare porous SnO2 and SnO2/C composite with Cu-Sn alloy as raw material by wet chemical reaction strategy has been developed. The prepared porous SnO2 and its carbon composite showed homogeneous mesoporous structure and high surface area, displayed superior rate performance and high reversible capacity of 625 mAh g-1 and 1185 mAh g-1 over 800 cycles at 0.4 A g-1, respectively. Compared with commercial SnO2, porous SnO2 sensor presented higher response, faster response/recovery capability, good selectivity and repeatability to ethanol at 180°C.

New SnO2/MgAl-layered double hydroxide composites as photocatalysts for cationic dyes bleaching.

PubMed

Dvininov, E; Ignat, M; Barvinschi, P; Smithers, M A; Popovici, E

2010-05-15

A new type of nanocomposite containing SnO(2) has been obtained by wet impregnation of dehydrated Mg/Al-hydrotalcite-type compounds with ethanolic solutions of SnCl(4).2H(2)O. Tin chloride hydrolysis was achieved using NaOH or NH(4)OH aqueous solutions, at pH around 9, followed by the conversion into corresponding hydroxides through calcinations. The powder X-ray diffraction (PXRD) and UV-Vis diffuse reflectance (UV-DR) methods confirmed the structure of as-synthesized solids. The chemical composition and morphology of the synthesized materials were investigated by energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The as-synthesized materials were used for photocatalytic studies showing a good activity for methylene blue decolourization, which varies with SnO(2) content and used as a hydrolysing agent. The proposed mechanism is based on the shifting of flat band potential of SnO(2) due to the interaction with Mg/Al-LDH, this being energetically favourable to the formation of hydroxyl radicals responsible for methylene blue degradation. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Expression profiling of snoRNAs in normal hematopoiesis and AML

PubMed Central

Warner, Wayne A.; Spencer, David H.; Trissal, Maria; White, Brian S.; Helton, Nichole; Ley, Timothy J.

2018-01-01

Small nucleolar RNAs (snoRNAs) are noncoding RNAs that contribute to ribosome biogenesis and RNA splicing by modifying ribosomal RNA and spliceosome RNAs, respectively. We optimized a next-generation sequencing approach and a custom analysis pipeline to identify and quantify expression of snoRNAs in acute myeloid leukemia (AML) and normal hematopoietic cell populations. We show that snoRNAs are expressed in a lineage- and development-specific fashion during hematopoiesis. The most striking examples involve snoRNAs located in 2 imprinted loci, which are highly expressed in hematopoietic progenitors and downregulated during myeloid differentiation. Although most snoRNAs are expressed at similar levels in AML cells compared with CD34+, a subset of snoRNAs showed consistent differential expression, with the great majority of these being decreased in the AML samples. Analysis of host gene expression, splicing patterns, and whole-genome sequence data for mutational events did not identify transcriptional patterns or genetic alterations that account for these expression differences. These data provide a comprehensive analysis of the snoRNA transcriptome in normal and leukemic cells and should be helpful in the design of studies to define the contribution of snoRNAs to normal and malignant hematopoiesis. PMID:29365324

Improved Li storage performance in SnO 2 nanocrystals by a synergetic doping

DOE PAGES

Wan, Ning; Lu, Xia; Wang, Yuesheng; ...

2016-01-06

Tin dioxide (SnO 2) is a widely investigated lithium (Li) storage material because of its easy preparation, two-step storage mechanism and high specific capacity for lithium-ion batteries (LIBs). In this contribution, a phase-pure cobalt-doped SnO 2 (Co/SnO 2) and a cobalt and nitrogen co-doped SnO 2 (Co-N/SnO 2) nanocrystals are prepared to explore their Li storage behaviors. It is found that the morphology, specific surface area, and electrochemical properties could be largely modulated in the doped and co-doped SnO 2 nanocrystals. Gavalnostatic cycling results indicate that the Co-N/SnO 2 electrode delivers a specific capacity as high as 716 mAh gmore » –1 after 50 cycles, and the same outstanding rate performance can be observed in subsequent cycles due to the ionic/electronic conductivity enhancement by co-doping effect. Further, microstructure observation indicates the existence of intermediate phase of Li 3N with high ionic conductivity upon cycling, which probably accounts for the improvements of Co-N/SnO 2 electrodes. Furthermore, we find that the method of synergetic doping into SnO 2 with Co and N, with which the electrochemical performances is enhanced remarkably, undoubtedly, will have an important influence on the material itself and community of LIBs as well.« less

Ultrahigh broadband photoresponse of SnO2 nanoparticle thin film/SiO2/p-Si heterojunction.

PubMed

Ling, Cuicui; Guo, Tianchao; Lu, Wenbo; Xiong, Ya; Zhu, Lei; Xue, Qingzhong

2017-06-29

The SnO 2 /Si heterojunction possesses a large band offset and it is easy to control the transportation of carriers in the SnO 2 /Si heterojunction to realize high-response broadband detection. Therefore, we investigated the potential of the SnO 2 nanoparticle thin film/SiO 2 /p-Si heterojunction for photodetectors. It is demonstrated that this heterojunction shows a stable, repeatable and broadband photoresponse from 365 nm to 980 nm. Meanwhile, the responsivity of the device approaches a high value in the range of 0.285-0.355 A W -1 with the outstanding detectivity of ∼2.66 × 10 12 cm H 1/2 W -1 and excellent sensitivity of ∼1.8 × 10 6 cm 2 W -1 , and its response and recovery times are extremely short (<0.1 s). This performance makes the device stand out among previously reported oxide or oxide/Si based photodetectors. In fact, the photosensitivity and detectivity of this heterojunction are an order of magnitude higher than that of 2D material based heterojunctions such as (Bi 2 Te 3 )/Si and MoS 2 /graphene (photosensitivity of 7.5 × 10 5 cm 2 W -1 and detectivity of ∼2.5 × 10 11 cm H 1/2 W -1 ). The excellent device performance is attributed to the large Fermi energy difference between the SnO 2 nanoparticle thin film and Si, SnO 2 nanostructure, oxygen vacancy defects and thin SiO 2 layer. Consequently, practical highly-responsive broadband PDs may be actualized in the future.

Laser induced forward transfer of SnO2 for sensing applications using different precursors systems

NASA Astrophysics Data System (ADS)

Mattle, Thomas; Hintennach, Andreas; Lippert, Thomas; Wokaun, Alexander

2013-02-01

This paper presents the transfer of SnO2 by laser induced forward transfer (LIFT) for gas sensor applications. Different donor substrates of SnO2 with and without triazene polymer (TP) as a dynamic release layer were prepared. Transferring these films under different conditions were evaluated by optical microscopy and functionality. Transfers of sputtered SnO2 films do not lead to satisfactory results and transfers of SnO2 nanoparticles are difficult. Transfers of SnO2 nanoparticles can only be achieved when applying a second laser pulse to the already transferred material, which improves the adhesion resulting in a complete pixel. A new approach of decomposing the transfer material during LIFT transfer was developed. Donor films based on UV absorbing metal complex precursors namely, SnCl2(acac)2 were prepared and transferred using the LIFT technique. Transfer conditions were optimized for the different systems, which were deposited onto sensor-like microstructures. The conductivity of the transferred material at temperatures of about 400 ∘C are in a range usable for SnO2 gas sensors. First sensing tests were carried out and the transferred material proved to change conductivity when exposed to ethanol, acetone, and methane.

LPG sensing characteristics of electrospray deposited SnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Gürbüz, Mevlüt; Günkaya, Göktuğ; Doğan, Aydın

2014-11-01

In this study, SnO2 films were fabricated on conductive substrate such as aluminum and platinum coated alumina using electro-spray deposition (ESD) method for gas sensor applications. Solution flow rate, coating time, substrate-nozzle distance and solid/alcohol ratio were studied to optimize SnO2 film structure. The morphology of the deposited films was characterized by stereo and scanning electron microscopy (SEM). The gas sensing properties of tin oxide films were investigated using liquid petroleum gas (LPG) for various lower explosive limit (LEL). The results obtained from microscopic analyses show that optimum SnO2 films were evaluated at flow rate of 0.05 ml/min, at distance of 6 cm, for 10 min deposition time, for 20 gSnO2/Lethanol ratio and at 7 kV DC electric field. By the results obtained from the gas sensing behavior, the sensitivity of the films was increased with operating temperature. The films showed better sensitivity for 20 LEL LPG concentration at 450 °C operating temperature.

Thermoelectric Properties in the TiO2/SnO2 System

NASA Technical Reports Server (NTRS)

Dynys, F.; Sayir, A.; Sehirlioglu, A.; Berger, M.

2009-01-01

Nanotechnology has provided a new interest in thermoelectric technology. A thermodynamically driven process is one approach in achieving nanostructures in bulk materials. TiO2/SnO2 system exhibits a large spinodal region with exceptional stable phase separated microstructures up to 1400 C. Fabricated TiO2/SnO2 nanocomposites exhibit n-type behavior with Seebeck coefficients greater than -300 .V/K. Composites exhibit good thermal conductance in the range of 7 to 1 W/mK. Dopant additions have not achieved high electrical conductivity (<1000 S/m). Formation of oxygen deficient composites, TixSn1-xO2-y, can change the electrical conductivity by four orders of magnitude. Achieving higher thermoelectric ZT by oxygen deficiency is being explored. Seebeck coeffcient, thermal conductivity, electrical conductance and microstructure will be discussed in relation to composition and doping.

Investigation of the structure and stability of SnO2 nanocrystal and its surface-bound water

NASA Astrophysics Data System (ADS)

Wang, H.; Wesolowski, D. J.; Proffen, T. E.; Kolesnikov, A. I.; Vlcek, L.; Wang, W.; Feygenson, M.; Sofo, J. O.; Anovitz, L.

2012-12-01

Driven partly by a myriad use of engineered metal oxide nanoparticles, understanding their stabilities and interactions with environmental matrix during and after applications are desired. SnO2 (cassiterite) is one of the frequently used oxides in solid-state gas sensors and oxidation catalysts. A close relationship between the gas sensitivity and catalysis of oxides with their surface chemistry ensures continuous interests in the study of SnO2-water interfacial complexity (unavoidable "contamination" in which water can potentially participate in reactions and change SnO2 conductivity). Such information is important, as the existence of hydration layers on the surface of SnO2 nanoparticles not only play a critical role in stabilizing the nanoparticle but also affect its selectivity/sensitivity, as a nanosensor. SnO2 nanoparticles (2-5 nm) synthesized by a wet chemical route are dominated by {110} faces and are capped with H2O or D2O water molecules (after purification), depending on isotopic composition of water used for syntheses. When water is in direct contact with terminal Sn and O atoms, there is a controversial argument as to whether or not dissociative adsorption occurs (i.e., formation of hydroxyl groups). Although theoretical studies point toward a tendency for dissociative configuration in the direct contact layer, experimental studies have not unambiguously confirmed this conclusion. We present combined investigations using neutron total scattering (NPDF at the NOMAD beamline, SNS) and inelastic neutron scattering (INS at the SEQUOIA beamline, SNS) techniques as static and dynamic probes to reveal structure and dynamics of water and SnO2 nanocrystalline stability upon dehydration. The NPDF results (measured with deuterated samples) suggest layered water configurations with G(r) signals dominated by O-D bonds at 0.98 Å, and the second hydration layer that gives a broad peak at 2.5-4 Å. There is no evidence of a third hydration layer at 5-7 Å as shown

Highly uniform and vertically aligned SnO2 nanochannel arrays for photovoltaic applications

NASA Astrophysics Data System (ADS)

Kim, Jae-Yup; Kang, Jin Soo; Shin, Junyoung; Kim, Jin; Han, Seung-Joo; Park, Jongwoo; Min, Yo-Sep; Ko, Min Jae; Sung, Yung-Eun

2015-04-01

Nanostructured electrodes with vertical alignment have been considered ideal structures for electron transport and interfacial contact with redox electrolytes in photovoltaic devices. Here, we report large-scale vertically aligned SnO2 nanochannel arrays with uniform structures, without lateral cracks fabricated by a modified anodic oxidation process. In the modified process, ultrasonication is utilized to avoid formation of partial compact layers and lateral cracks in the SnO2 nanochannel arrays. Building on this breakthrough, we first demonstrate the photovoltaic application of these vertically aligned SnO2 nanochannel arrays. These vertically aligned arrays were directly and successfully applied in quasi-solid state dye-sensitized solar cells (DSSCs) as photoanodes, yielding reasonable conversion efficiency under back-side illumination. In addition, a significantly short process time (330 s) for achieving the optimal thickness (7.0 μm) and direct utilization of the anodized electrodes enable a simple, rapid and low-cost fabrication process. Furthermore, a TiO2 shell layer was coated on the SnO2 nanochannel arrays by the atomic layer deposition (ALD) process for enhancement of dye-loading and prolonging the electron lifetime in the DSSC. Owing to the presence of the ALD TiO2 layer, the short-circuit photocurrent density (Jsc) and conversion efficiency were increased by 20% and 19%, respectively, compared to those of the DSSC without the ALD TiO2 layer. This study provides valuable insight into the development of efficient SnO2-based photoanodes for photovoltaic application by a simple and rapid fabrication process.Nanostructured electrodes with vertical alignment have been considered ideal structures for electron transport and interfacial contact with redox electrolytes in photovoltaic devices. Here, we report large-scale vertically aligned SnO2 nanochannel arrays with uniform structures, without lateral cracks fabricated by a modified anodic oxidation process

Synthesis and properties of Li2SnO3/polyaniline nanocomposites as negative electrode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wang, Qiufen; Huang, Ying; Miao, Juan; Zhao, Yang; Wang, Yan

2012-10-01

The nanocomposites Li2SnO3/polyaniline (Li2SnO3/PANI) have been synthesized by a micro emulsion polymerization method. The structure, morphology and electrochemical properties of the as-prepared materials are characterized by XRD, FTIR, Raman, XPS, TGA, TEM and electrochemical measurements. Results show that Li2SnO3/PANI nanocomposites are composed of uniform and blocky nano-sized particles (40-50 nm) with clear lattice fringes. Electrochemical measurement suggests that Li2SnO3/PANI exhibits better cycling properties and lower initial irreversible capacities than Li2SnO3 as negative electrodes materials for lithium-ion batteries. At a current density of 60 mA g-1 in the voltage about 0.05-2.0 V, the initial irreversible capacity of Li2SnO3/PANI is 563 mAh g-1 while it is 687.5 mAh g-1 to Li2SnO3. The capacity retained of Li2SnO3/PANI (569.2 mAh g-1) is higher than that of Li2SnO3 (510.2 mAh g-1) after 50 cycles. The PANI in the Li2SnO3/PANI nanocomposites can buffer the released stress caused by the drastic volume variation during the alloying/de-alloying process of Li-Sn.

Zr-doped SnO2 thin films synthesized by spray pyrolysis technique for barrier layers in solar cells

NASA Astrophysics Data System (ADS)

Reddy, N. Nanda Kumar; Akkera, Harish Sharma; Sekhar, M. Chandra; Park, Si-Hyun

2017-12-01

In the present work, we investigated the effect of Zr doping (0-6 at%) on the structural, electrical, and optical properties of tin oxide (SnO2) thin films deposited onto glass substrates using a spray pyrolysis technique. The room-temperature X-ray diffraction pattern shows that all deposited films exhibit polycrystalline tetragonal structure. The pure SnO2 film is grown along a preferred (200) direction, whereas Zr-doped SnO2 (Zr:SnO2) films started growing along the (220) orientation along with a high intensity peak of (200). Scanning electron microscope (SEM) and atomic force microscope (AFM) images showed that the grains of the films are spherical in structure, and the grain size decreased with increasing of Zr concentration. The optical transmission spectra of deposited films as a function of wavelength confirm that the average optical transmittance is > 85% for Zr:SnO2 films. The value of the optical bandgap is significantly decreased from 3.94 to 3.68 eV with increasing Zr concentration. Furthermore, the electrical measurements found that the sheet resistance ( R sh) and resistivity ( ρ) values are decreased with increasing of Zr doping. The lowest values of R sh = 6.82 Ω and ρ = 0.4 × 10- 3 Ω cm are found in 6-at% Zr-doped SnO2 film. In addition, a good efficiency value of the figure of merit ( ɸ = 3.35 × 10- 3 Ω-1) is observed in 6-at% Zr-doped SnO2 film. These outstanding properties of Zr-doped SnO2 films make them useful for several optoelectronic device applications.

Interplay between O2 and SnO2: oxygen ionosorption and spectroscopic evidence for adsorbed oxygen.

PubMed

Gurlo, Alexander

2006-10-13

Tin dioxide is the most commonly used material in commercial gas sensors based on semiconducting metal oxides. Despite intensive efforts, the mechanism responsible for gas-sensing effects on SnO(2) is not fully understood. The key step is the understanding of the electronic response of SnO(2) in the presence of background oxygen. For a long time, oxygen interaction with SnO(2) has been treated within the framework of the "ionosorption theory". The adsorbed oxygen species have been regarded as free oxygen ions electrostatically stabilized on the surface (with no local chemical bond formation). A contradiction, however, arises when connecting this scenario to spectroscopic findings. Despite trying for a long time, there has not been any convincing spectroscopic evidence for "ionosorbed" oxygen species. Neither superoxide ions O(2)(-), nor charged atomic oxygen O,(-) nor peroxide ions O(2)(2-) have been observed on SnO(2) under the real working conditions of sensors. Moreover, several findings show that the superoxide ion does not undergo transformations into charged atomic oxygen at the surface, and represents a dead-end form of low-temperature oxygen adsorption on reduced metal oxide.

Metal-Organic Frameworks Derived Okra-like SnO2 Encapsulated in Nitrogen-Doped Graphene for Lithium Ion Battery.

PubMed

Zhou, Xiangyang; Chen, Sanmei; Yang, Juan; Bai, Tao; Ren, Yongpeng; Tian, Hangyu

2017-04-26

A facile process is developed to prepare SnO 2 -based composites through using metal-organic frameworks (MOFs) as precursors. The nitrogen-doped graphene wrapped okra-like SnO 2 composites (SnO 2 @N-RGO) are successfully synthesized for the first time by using Sn-based metal-organic frameworks (Sn-MOF) as precursors. When utilized as an anode material for lithium-ion batteries, the SnO 2 @N-RGO composites possess a remarkably superior reversible capacity of 1041 mA h g -1 at a constant current of 200 mA g -1 after 180 charge-discharge processes and excellent rate capability. The excellent performance can be primarily ascribed to the unique structure of 1D okra-like SnO 2 in SnO 2 @N-RGO which are actually composed of a great number of SnO 2 primary crystallites and numerous well-defined internal voids, can effectively alleviate the huge volume change of SnO 2 , and facilitate the transport and storage of lithium ions. Besides, the structural stability acquires further improvement when the okra-like SnO 2 are wrapped by N-doped graphene. Similarly, this synthetic strategy can be employed to synthesize other high-capacity metal-oxide-based composites starting from various metal-organic frameworks, exhibiting promising application in novel electrode material field of lithium-ion batteries.

An insight into the origin of room-temperature ferromagnetism in SnO2 and Mn-doped SnO2 quantum dots: an experimental and DFT approach.

PubMed

Manikandan, Dhamodaran; Boukhvalov, D W; Amirthapandian, S; Zhidkov, I S; Kukharenko, A I; Cholakh, S O; Kurmaev, E Z; Murugan, Ramaswamy

2018-02-28

SnO 2 and Mn-doped SnO 2 single-phase tetragonal crystal structure quantum dots (QDs) of uniform size with control over dopant composition and microstructure were synthesized using the high pressure microwave synthesis technique. On a broader vision, we systematically investigated the influence of dilute Mn ions in SnO 2 under the strong quantum confinement regime through various experimental techniques and density functional theoretical (DFT) calculations to disclose the physical mechanism governing the observed ferromagnetism. DFT calculations revealed that the formation of the stable (001) surface was much more energetically favorable than that of the (100) surface, and the formation energy of the oxygen vacancies in the stable (001) surface was comparatively higher in the undoped SnO 2 QDs. X-ray photoelectron spectroscopy (XPS) and first-principles modeling of doped QDs revealed that the lower doping concentration of Mn favored the formation of MnO-like (Mn 2+ ) structures in defect-rich areas and the higher doping concentration of Mn led to the formation of multiple configurations of Mn (Mn 2+ and Mn 3+ ) in the stable surfaces of SnO 2 QDs. Electronic absorption spectra indicated the characteristic spin allowed ligand field transitions of Mn 2+ and Mn 3+ and the red shift in the band gap. DFT calculations clearly indicated that only the substitutional dopant antiferromagnetic configurations were more energetically favorable. The gradual increase of magnetization at a low level of Mn-doping could be explained by the prevalence of antiferromagnetic manganese-vacancy pairs. Higher concentrations of Mn led to the appearance of ferromagnetic interactions between manganese and oxygen vacancies. The increase in the concentration of metallic dopants caused not just an increase in the total magnetic moment of the system but also changed the magnetic interactions between the magnetic moments on the metal ions and oxygen. The present study provides new insight into the

Effect of size on structural, optical and magnetic properties of SnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Thamarai Selvi, E.; Meenakshi Sundar, S.

2017-07-01

Tin Oxide (SnO2) nanostructures were synthesized by a microwave oven assisted solvothermal method using with and without cetyl trimethyl ammonium bromide (CTAB) capping agent. XRD confirmed the pure rutile-type tetragonal phase of SnO2 for both uncapped and capped samples. The presence of functional groups was analyzed by Fourier transform infrared spectroscopy. Scanning electron microscopy shows the morphology of the samples. Transmission electron microscopy images exposed the size of the SnO2 nanostructures. Surface defect-related g factor of SnO2 nanoparticles using fluorescence spectroscopy is shown. For both uncapped and capped samples, UV-visible spectrum shows a blue shift in absorption edge due to the quantum confinement effect. Defect-related bands were identified by electron paramagnetic resonance (EPR) spectroscopy. The magnetic properties were studied by using vibrating sample magnetometer (VSM). A high value of magnetic moment 0.023 emu g-1 at room temperature for uncapped SnO2 nanoparticles was observed. Capping with CTAB enhanced the saturation magnetic moment to high value of 0.081 emu g-1 by altering the electronic configuration on the surface.

Optical calibration of SNO +

NASA Astrophysics Data System (ADS)

Leming, Edward; SNO+ Collaboration

2015-04-01

Situated 2 km underground in Sudbury, Northern Ontario, the SNO + detector consists of an acrylic sphere 12 m in diameter containing 780 tons of target mass, surrounded by approximately 9,500 PMTs. For SNO, this target mass was heavy water, however the change to SNO + is defined by the change of this target mass to a novel scintillator. With the lower energy threshold, low intrinsic radioactivity levels and the best shielding against muons and cosmogenic activation of all existing neutrino experiments, SNO + will be sensitive to exciting new physics. The experiment will be studying solar, reactor, super nova and geo-neutrinos, though the main purpose of SNO + is the search for neutrinoless double-beta decay of Te-130. To meet the requirements imposed by the physics on detector performance, a detailed optical calibration is needed. Source deployment must be kept to a minimum and eliminated if possible, in order to meet the stringent radiopurity requirements. This led to the development of the Embedded LED/laser Light Injection Entity (ELLIE) system. This talk provides a summary of the upgrades to from SNO to SNO +, discussing the requirements on and methods of optical calibration, focusing on the deployed laserball and ELLIE system.

Electrochemical and fluorescence properties of SnO2 thin films and its antibacterial activity

NASA Astrophysics Data System (ADS)

Henry, J.; Mohanraj, K.; Sivakumar, G.; Umamaheswari, S.

2015-05-01

Nanocrystalline SnO2 thin films were deposited by a simple and inexpensive sol-gel spin coating technique and the films were annealed at two different temperatures (350 °C and 450 °C). Structural, vibrational, optical and electrochemical properties of the films were analyzed using XRD, FTIR, UV-Visible, fluorescence and cyclic voltammetry techniques respectively and their results are discussed in detail. The antimicrobial properties of SnO2 thin films were investigated by agar agar method and the results confirm the antibacterial activity of SnO2 against Escherichia coli and Bacillus.

Field emission from in situ-grown vertically aligned SnO2 nanowire arrays

PubMed Central

2012-01-01

Vertically aligned SnO2 nanowire arrays have been in situ fabricated on a silicon substrate via thermal evaporation method in the presence of a Pt catalyst. The field emission properties of the SnO2 nanowire arrays have been investigated. Low turn-on fields of 1.6 to 2.8 V/μm were obtained at anode-cathode separations of 100 to 200 μm. The current density fluctuation was lower than 5% during a 120-min stability test measured at a fixed applied electric field of 5 V/μm. The favorable field-emission performance indicates that the fabricated SnO2 nanowire arrays are promising candidates as field emitters. PMID:22330800

Effect of Growth Parameters on SnO2 Nanowires Growth by Electron Beam Evaporation Method

NASA Astrophysics Data System (ADS)

Rakesh Kumar, R.; Manjula, Y.; Narasimha Rao, K.

2018-02-01

Tin oxide (SnO2) nanowires were synthesized via catalyst assisted VLS growth mechanism by the electron beam evaporation method at a growth temperature of 450 °C. The effects of growth parameters such as evaporation rate of Tin, catalyst film thickness, and different types of substrates on the growth of SnO2 nanowires were studied. Nanowires (NWs) growth was completely seized at higher tin evaporation rates due to the inability of the catalyst particle to initiate the NWs growth. Nanowires diameters were able to tune with catalyst film thickness. Nanowires growth was completely absent at higher catalyst film thickness due to agglomeration of the catalyst film. Optimum growth parameters for SnO2 NWs were presented. Nanocomposites such as Zinc oxide - SnO2, Graphene oxide sheets- SnO2 and Graphene nanosheets-SnO2 were able to synthesize at a lower substrate temperature of 450 °C. These nanocompsoites will be useful in enhancing the capacity of Li-ion batteries, the gas sensing response and also useful in increasing the photo catalytic activity.

Thermal stability enhancement of modified carboxymethyl cellulose films using SnO2 nanoparticles.

PubMed

Baniasad, Arezou; Ghorbani, Mohsen

2016-05-01

In this study, in-situ and ex-situ hydrothermal synthesis procedures were applied to synthesize novel CMC/porous SnO2 nanocomposites from rice husk extracted carboxymethyl cellulose (CMC) biopolymer. In addition, the effects of SnO2 nanoparticles on thermal stability of the prepared nanocomposite were specifically studied. Products were investigated in terms of morphology, particle size, chemical structure, crystallinity and thermal stability by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA), respectively. Presence of characteristic bands in the FTIR spectra of samples confirmed the successful formation of CMC and CMC/SnO2 nanocomposites. In addition, FESEM images revealed four different morphologies of porous SnO2 nanoparticles including nanospheres, microcubes, nanoflowers and olive-like nanoparticles with hollow cores which were formed on CMC. These nanoparticles possessed d-spacing values of 3.35Å. Thermal stability measurements revealed that introduction of SnO2 nanoparticles in the structure of CMC enhanced stability of CMC to 85%. Copyright © 2016 Elsevier B.V. All rights reserved.

Carbon-Coated Hierarchical SnO2 Hollow Spheres for Lithium Ion Batteries.

PubMed

Liu, Qiannan; Dou, Yuhai; Ruan, Boyang; Sun, Ziqi; Chou, Shu-Lei; Dou, Shi Xue

2016-04-18

Hierarchical SnO2 hollow spheres self-assembled from nanosheets were prepared with and without carbon coating. The combination of nanosized architecture, hollow structure, and a conductive carbon layer endows the SnO2 -based anode with improved specific capacity and cycling stability, making it more promising for use in lithium ion batteries. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SnO2 epitaxial films with varying thickness on c-sapphire: Structure evolution and optical band gap modulation

NASA Astrophysics Data System (ADS)

Zhang, Mi; Xu, Maji; Li, Mingkai; Zhang, Qingfeng; Lu, Yinmei; Chen, Jingwen; Li, Ming; Dai, Jiangnan; Chen, Changqing; He, Yunbin

2017-11-01

A series of a-plane SnO2 films with thickness between 2.5 nm and 1436 nm were grown epitaxially on c-sapphire by pulsed laser deposition (PLD), to allow a detailed probe into the structure evolution and optical band gap modulation of SnO2 with growing thickness. All films exhibit excellent out-of-plane ordering (lowest (200) rocking-curve half width ∼0.01°) with an orientation of SnO2(100) || Al2O3(0001), while three equivalent domains that are rotated by 120° with one another coexist in-plane with SnO2[010] || Al2O3 [11-20]. Initially the SnO2(100) film assumes a two-dimensional (2D) layer-by-layer growth mode with atomically smooth surface (minimum root-mean-square roughness of 0.183 nm), and endures compressive strain along both c and a axes as well as mild tensile strain along the b-axis. With increasing thickness, transition from the 2D to 3D island growth mode takes place, leading to formation of various defects to allow relief of the stress and thus relaxation of the film towards bulk SnO2. More interestingly, with increasing thickness from nm to μm, the SnO2 films present a non-monotonic V-shaped variation in the optical band gap energy. While the band gap of SnO2 films thinner than 6.1 nm increases rapidly with decreasing film thickness due to the quantum size effect, the band gap of thicker SnO2 films broadens almost linearly with increasing film thickness up to 374 nm, as a result of the strain effect. The present work sheds light on future design of SnO2 films with desired band gap for particular applications by thickness control and strain engineering.

Structural and spectroscopic study of mechanically synthesized SnO2 nanostructures

NASA Astrophysics Data System (ADS)

Vij, Ankush; Kumar, Ravi

2016-05-01

We report the single step synthesis of SnO2 nanostructures using high energy mechanical attrition method. X-ray diffraction (XRD) pattern reveals the single phase rutile structure with appreciable broadening of diffraction peaks, which is a signature of nanostructure formation. The average crystallite size of SnO2 nanostructures has been calculated to be ~15 nm. The micro-Raman study reveals the shifting of A1g Raman mode towards lower wave number, which is correlated with the nanostructure formation.

A Fast Humidity Sensor Based on Li+-Doped SnO2 One-Dimensional Porous Nanofibers

PubMed Central

Yin, Min; Yang, Fang; Wang, Zhaojie; Zhu, Miao; Liu, Ming; Xu, Xiuru; Li, Zhenyu

2017-01-01

One-dimensional SnO2- and Li+-doped SnO2 porous nanofibers were easily fabricated via electrospinning and a subsequent calcination procedure for ultrafast humidity sensing. Different Li dopant concentrations were introduced to investigate the dopant’s role in sensing performance. The response properties were studied under different relative humidity levels by both statistic and dynamic tests. The best response was obtained with respect to the optimal doping of Li+ into SnO2 porous nanofibers with a maximum 15 times higher response than that of pristine SnO2 porous nanofibers, at a relative humidity level of 85%. Most importantly, the ultrafast response and recovery time within 1 s was also obtained with the 1.0 wt % doping of Li+ into SnO2 porous nanofibers at 5 V and at room temperature, benefiting from the co-contributions of Li-doping and the one-dimensional porous structure. This work provides an effective method of developing ultrafast sensors for practical applications—especially fast breathing sensors. PMID:28772895

Azadirachta indica (neem) leaves mediated synthesis of SnO2/NiO nanocomposite and assessment of its photocatalytic activity

NASA Astrophysics Data System (ADS)

Varshney, Bhaskar; Shoeb, Mohd; Siddiqui, M. J.; Azam, Ameer; Mobin, Mohammad

2018-05-01

SnO2/NiO nanocomposite are prepared by using a simple cost effective and ecofriendly green soft template method followed by ultrasonication treatment further by calcination at 300 °C. The resulting nanocatalysts were characterized by X-ray diffraction (XRD), UV-Visible spectroscopy and transmission electron microscopy (TEM). The SnO2-NiO photocatalyst was made of a mesoporous network of aggregated NiO and cassiterite SnO2 nanocrystallites, the size of which was estimated to be 16.68 nm and 13.17 nm, respectively, after calcination. According to UV-visible spectroscopy, the evident energy band gap value of the SnO2-NiO photocatalyst was estimated to be 3.132 eV to be compared with those of pure SnO2, that is, 3.7 eV. Moreover, the heterostructure SnO2-NiO photocatalyst showed much higher photocatalytic activities for the degradation of methylene blue than those of individual SnO2 and NiO nanomaterials. This behaviour was rationalized in terms of better charge separation and the suppression of charge recombination in the SnO2-NiO photocatalyst because of the energy difference between the conduction band edges of SnO2 and NiO as evidenced by the band alignment determination. Finally, this mesoporous SnO2-NiO heterojunction nanocatalyst was stable and could be easily recycled several times opening new avenues for potential industrial applications.

Colloid electrostatic self-assembly synthesis of SnO2/graphene nanocomposite for supercapacitors

NASA Astrophysics Data System (ADS)

Wang, Yankun; Liu, Yushan; Zhang, Jianmin

2015-10-01

In this paper, a simple and fast colloid electrostatic self-assembly method was adopted to prepare the SnO2/graphene nanocomposite (SGNC). The crystal structure, chemical composition, and porous property of composite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman microscopy, X-ray photoelectron spectroscopy (XPS), and N2 adsorption-desorption experiments. The morphology analyses showed that the SnO2 nanoparticles about 5 nm were distributed homogenously on the reduced graphene oxide (rGO) sheets surface. The electrochemical performance measurements exhibited that SGNC possessed the specific capacitance of 347.3 F g-1 at a scan rate of 5 mV s-1 in 1 M Na2SO4 electrolyte solution. Furthermore, this material also showed excellent cycling stability, and the specific capacitance still retained 90 % after 3000 cycles. These results indicate that the SGNC is a promising electrode material for high-performance supercapacitors.

SnO2/Reduced Graphene Oxide Interlayer Mitigating the Shuttle Effect of Li-S Batteries.

PubMed

Hu, Nana; Lv, Xingshuai; Dai, Ying; Fan, Linlin; Xiong, Dongbin; Li, Xifei

2018-06-06

The short cycle life of lithium-sulfur batteries (LSBs) plagues its practical application. In this study, a uniform SnO 2 /reduced graphene oxide (denoted as SnO 2 /rGO) composite is successfully designed onto the commercial polypropylene separator for use of interlayer of LSBs to decrease the charge-transfer resistance and trap the soluble lithium polysulfides (LPSs). As a result, the assembled devices using the separator modified with the functional interlayer (SnO 2 /rGO) exhibit improved cycle performance; for instance, over 200 cycles at 1C, the discharge capacity of the cells reaches 734 mAh g -1 . The cells also display high rate capability, with the average discharge capacity of 541.9 mAh g -1 at 5C. Additionally, the mechanism of anchoring behavior of the SnO 2 /rGO interlayer was systematically investigated using density functional theory calculations. The results demonstrate that the improved performance is related to the ability of SnO 2 /rGO to effectively absorb S 8 cluster and LPS. The strong Li-O/Sn-S/O-S bonds and tight chemical adsorption between LPS and SnO 2 mitigate the shuttle effect of LSBs. This study demonstrates that engineering the functional interlayer of metal oxide and carbon materials in LSBs may be an easy way to improve their rate capacity and cycling life.

Deformation Microstructures Near Vickers Indentations in SNO2/SI Coated Systems

NASA Astrophysics Data System (ADS)

Daria, G.; Evghenii, H.; Olga, S.; Zinaida, D.; Iana, M.; Victor, Z.

The micromechanical properties (hardness and brittleness) of the hard-on-hard SnO2 / Si-coated system (CS) and their modification depending the on load value has been studied. A nonmonotonic changing of microhardness with load growth was detected. The brittle/plastic behavior of the rigid/hard-on-hard SnO2 / Si CS and its response to concentrated load action explains it.A specific evolution of the indentation-deformed zone vs. load value attributed to the change in the internal stress redistribution between film and substrate was detected. It results in a brittleness indentation size effect (BISE) of the SnO2 / Si CS revealed in this experiment.It was shown that the greater portion of internal stresses under indentation is concentrated in the coating layer at small loads. This fact causes a strong elastic-plastic relaxation in the film and its delamination from substrate. The increase of brittle failure in the indentation-deformed zone with a decrease of indentation load was revealed.

Polyaniline assisted by TiO2:SnO2 nanoparticles as a hydrogen gas sensor at environmental conditions

NASA Astrophysics Data System (ADS)

Nasirian, Shahruz; Milani Moghaddam, Hossain

2015-02-01

In the present research, polyaniline assisted by TiO2:SnO2 nanoparticles was synthesized and deposited onto an epoxy glass substrate with Cu-interdigited electrodes for gas sensing application. To examine the efficiency of the polyaniline/TiO2:SnO2 nanocomposite (PTS) as a hydrogen (H2) gas sensor, its nature, stability, response, recovery/response time have been studied with a special focus on its ability to work at environmental conditions. H2 gas sensing results demonstrated that a PTS sensor with 20 and 10 wt% of anatase-TiO2 and SnO2 nanoparticles, respectively, has the best response time (75 s) with a recovery time of 117 s at environmental conditions. The highest (lowest) response (recovery time) was 6.18 (46 s) in PTS sensor with 30 and 15 wt% of anatase- (rutile-)TiO2 and SnO2 nanoparticles, respectively, at 0.8 vol.% H2 gas. Further, the H2 gas sensing mechanism of PTS sensor has also been studied.

Commissioning the SNO+ detector

NASA Astrophysics Data System (ADS)

Descamps, Freija; SNO+ Collaboration

2016-09-01

The SNO+ experiment is the successor to the Sudbury Neutrino Observatory (SNO), in which SNO's heavy water is replaced by approximately 780T of liquid scintillator (LAB). The combination of the 2km underground location, the use of ultra-clean materials and the high light-yield of the liquid scintillator means that a low background level and a low energy threshold can be achieved. This creates a new multipurpose neutrino detector with the potential to address a diverse set of physics goals, including the detection of reactor, solar, geo- and supernova neutrinos. A main physics goal of SNO+ is the search for neutrinoless double beta decay. By loading the liquid scintillator with 0.5% of natural Tellurium, resulting in about 1300kg of 130Te (isotopic abundance is slightly over 34%), a competitive sensitivity to the effective neutrino mass can be reached. This talk will present the status of the SNO+ detector, specifically the results and status of the detector commissioning with water.

Ethanol chemiresistor with enhanced discriminative ability from acetone based on Sr-doped SnO2 nanofibers.

PubMed

Jiang, Ziqiao; Jiang, Tingting; Wang, Jinfeng; Wang, Zhaojie; Xu, Xiuru; Wang, Zongxin; Zhao, Rui; Li, Zhenyu; Wang, Ce

2015-01-01

We demonstrated a new metal oxides based chemiresistor (MOC), which exhibits fast response/recovery behavior, large sensitivity, and good selectivity to ethanol, enabled by Sr-doped SnO2 nanofibers via simple electrospinning and followed by calcination. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS) were carefully used to characterize their morphology, structure, and composition. The ethanol sensing performances based on Sr-doped SnO2 nanofibers were investigated. Comparing with the pristine SnO2 nanofibers, enhanced ethanol sensing performances (more rapid response/recovery behavior and larger response values) have been achieved owing to the basic SnO2 surface caused by Sr-doping, whereas the acetone sensing performances have been weakened. Thus, good discriminative ability to ethanol from acetone has been realized. Additionally, Sr-doped SnO2 nanofibers also exhibit good selectivity. Copyright © 2014 Elsevier Inc. All rights reserved.

Enhanced photo-, sono- and sonophotocatalysis of methylene blue via SnO2 nanoparticle supported on nanographene platelets (NGP)

NASA Astrophysics Data System (ADS)

Paramarta, V.; Taufik, A.; Saleh, R.

2017-07-01

In our previous study, we have reported the catalytic (photo- and sono-) performance of SnO2 nanoparticles in methylene blue (MB) removal from aqueous solution. In this study, SnO2/nanographene platelets (NGP) composites were fabricated by depositing SnO2 nanoparticle onto nanographene platelets surface to develop photo-, sono-, and sonophotocatalysts, SnO2 nanoparticle, and SnO2/NGP composites were successfully synthesized using the sol-gel and coprecipitation method, respectively. The nanographene platelets (NGP) content was varied from 5, 10, and 15 weight percentages (wt.%). The optical properties and thermal stability of the samples were characterized using X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and Thermal Gravimetric Analysis (TGA). The catalytic ability of the samples was investigated using photo-, sono-, and sonophoto degradation of MB which was observed when nanographene platelets (NGP) were added into SnO2 nanocomposite. The photo-, sono- and sonophotocatalytic activities of SnO2/NGP composites on dyes were analyzed by measuring the change in absorbance of dyes under UV-spectrophotometer. The degradation of the organic dyes has been calculated by monitoring the degradation in concentration of the dyes before and after irradiation of UV light, ultrasound, and both of them respectively. The influence of other parameters such as catalyst dosage, pH, and scavenger have also been investigated. The results showed that SnO2/NGP composite with 10 weight percent (wt.%) has better catalytic performance than pure SnO2 nanoparticle. The reusability tests have also been done to ensure the stability of the used catalysts.

Structural anisotropy in amorphous SnO2 film probed by X-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Zhu, Q.; Ma, Q.; Buchholz, D. B.; Chang, R. P. H.; Bedzyk, M. J.; Mason, T. O.

2013-07-01

Polarization-dependent X-ray absorption measurements reveal the existence of structural anisotropy in amorphous (a-) SnO2 film. The anisotropy is readily seen for the second neighbor interaction whose magnitude differs along three measured directions. The differences can be well accounted for by 10%-20% variation in the Debye-Waller factor. Instead of a single Gaussian distribution found in crystalline SnO2, the Sn-O bond distribution is bimodal in a-SnO2 whose separation shows a weak angular dependence. The oxygen vacancies, existing in the a-SnO2 film in the order of 1021 cm-3, distribute preferentially along the film surface direction.

The improvement of gas-sensing properties of SnO2/zeolite-assembled composite

NASA Astrophysics Data System (ADS)

Sun, Yanhui; Wang, Jing; Li, Xiaogan; Du, Haiying; Huang, Qingpan

2018-05-01

SnO2-impregnated zeolite composites were used as gas-sensing materials to improve the sensitivity and selectivity of the metal oxide-based resistive-type gas sensors. Nanocrystalline MFI type zeolite (ZSM-5) was prepared by hydrothermal synthesis. Highly dispersive SnO2 nanoparticles were then successfully assembled on the surface of the ZSM-5 nanoparticles by using the impregnation methods. The SnO2 nanoparticles are nearly spherical with the particle size of 10 nm. An enhanced formaldehyde sensing of as-synthesized SnO2-ZSM-5-based sensor was observed whereas a suppression on the sensor response to other volatile organic vapors (VOCs) such as acetone, ethanol, and methanol was noticed. The possible reasons for this contrary observation were proposed to be related to the amount of the produced water vapor during the sensing reactions assisted by the ZSM-5 nanoparticles. This provides a possible new strategy to improve the selectivity of the gas sensors. The effect of the humidity on the sensor response to formaldehyde was investigated and it was found the higher humidity would decrease the sensor response. A coating layer of the ZSM-5 nanoparticles on top of the SnO2-ZSM-5-sensing film was thus applied to further improve the sensitivity and selectivity of the sensor through the strong adsorption ability to polar gases and the "filtering effect" by the pores of ZSM-5.

Fluorine incorporation into SnO2 nanoparticles by co-milling with polyvinylidene fluoride

NASA Astrophysics Data System (ADS)

Senna, Mamoru; Turianicová, Erika; Šepelák, Vladimír; Bruns, Michael; Scholz, Gudrun; Lebedkin, Sergei; Kübel, Christian; Wang, Di; Kaňuchová, Mária; Kaus, Maximilian; Hahn, Horst

2014-04-01

Fluorine was incorporated into SnO2 nanoparticles from polyvinylidene fluoride (PVdF) by co-milling. The incorporation process was triggered by an oxidative partial decomposition of PVdF due to the abstraction of oxygen atoms, and began soon after milling with a simultaneous decrease in the crystallite size of SnO2 from 56 nm to 19 nm, and increase in the lattice strain by a factor 7. Appearance of D and G Raman peaks indicated that the decomposition of PVdF was accompanied by the formation of nanometric carbon species. Decomposing processes of PVdF were accompanied by the continuous change in the states of F, with a decrease of C-F in PVdF and increase in Sn-F. This indicates the gradual incorporation of F into SnO2, by replacing a part of oxygen in the oxide with fluorine. These serial mechanochemical reaction processes were discussed on the basis of X-ray diffractometry, FT-IR, Raman and UV-Vis diffuse reflectance spectroscopy, transmission electron microscopy, F1s, Sn3d and C1s X-ray photoelectron spectroscopy and Auger electron spectra, as well as magic angle spinning NMR spectroscopy of 19F and 119Sn. The present findings serve as an initial stage of incorporating fluorine into SnO2 via a solvent-free solid-state process, toward the rational fabrication of fluorine doped SnO2 powders.

Promotional effect of surface hydroxyls on electrochemical reduction of CO 2 over SnO x/Sn electrode

DOE PAGES

Cui, Chaonan; Han, Jinyu; Zhu, Xinli; ...

2016-01-16

In this study, tin oxide (SnO x) formation on tin-based electrode surfaces during CO 2 electrochemical reduction can have a significant impact on the activity and selectivity of the reaction. In the present study, density functional theory (DFT) calculations have been performed to understand the role of SnO x in CO 2 reduction using a SnO monolayer on the Sn(112) surface as a model for SnO x. Water molecules have been treated explicitly and considered actively participating in the reaction. The results showed that H 2O dissociates on the perfect SnO monolayer into two hydroxyl groups symmetrically on the surface.more » CO 2 energetically prefers to react with the hydroxyl, forming a bicarbonate (HCO 3(t)*) intermediate, which can then be reduced to either formate (HCOO*) by hydrogenating the carbon atom or carboxyl (COOH*) by protonating the oxygen atom. Both steps involve a simultaneous Csingle bondO bond breaking. Further reduction of HCOO* species leads to the formation of formic acid in the acidic solution at pH < 4, while the COOH* will decompose to CO and H 2O via protonation. Whereas the oxygen vacancy (VO) in the oxide monolayer maybe formed by the reduction, it can be recovered by H 2O dissociation, resulting in two embedded hydroxyl groups. The results show that the hydroxylated surface with two symmetric hydroxyls is energetically more favorable for CO 2 reduction than the hydroxylated VO surface with two embedded hydroxyls. The reduction potential for the former has a limiting-potential of –0.20 V (RHE), lower than that for the latter (–0.74 V (RHE)). Compared to the pure Sn electrode, the formation of SnO x monolayer on the electrode under the operating conditions promotes CO 2 reduction more effectively by forming surface hydroxyls, thereby providing a new channel via COOH* to the CO formation, although formic acid is still the major reduction product.« less

Growth of Fe2O3/SnO2 nanobelt arrays on iron foil for efficient photocatalytic degradation of methylene blue

NASA Astrophysics Data System (ADS)

Lei, Rui; Ni, Hongwei; Chen, Rongsheng; Zhang, Bowei; Zhan, Weiting; Li, Yang

2017-04-01

Tin(IV) oxide has been intensively employed in optoelectronic devices due to its excellent electrical and optical properties. But the high recombination rates of the photogenerated electron-hole pairs of SnO2 nanomaterials often results in low photocatalytic efficiency. Herein, we proposed a facile route to prepare a novel Fe2O3/SnO2 heterojunction structure. The nanobelt arrays grown on iron foil naturally form a Schottky-type contact and provide a direct pathway for the photogenerated excitons. Hence, the Fe2O3/SnO2 nanobelt arrays exhibit much improved photocatalytic performance with the degradation rate constant on the Fe2O3/SnO2 film of approximately 12 times to that of α-Fe2O3 nanobelt arrays.

Highly sensitive nanostructure SnO2 based gas sensor for environmental pollutants

NASA Astrophysics Data System (ADS)

Korgaokar, Sushil; Moradiya, Meet; Prajapati, Om; Thakkar, Pranav; Pala, Jay; Savaliya, Chirag; Parikh, Sachin; Markna, J. H.

2017-05-01

A major quantity of pollutants are produced from industries and vehicles in the form of gas. New approaches are needed to solve well-known environmental pollutants like CO, CO2, NO2, SOx. Therefore detection with effective gas sensors is a vital part of pollution prevention efforts. There is a need to develop fast, rapid, cost-effective, highly sensitive, low power, and non-intrusive rugged sensors that can be easily installed. In the present study, nanostructured SnO2 used as a sensitive material in the devices and synthesized using hydrothermal process. The detailed development of the fabrication of SnO2 nanostructures gas sensor is described, which shows the remarkable change in the sensing properties with varying particle size. Additionally, we have used X-ray diffraction, scanning electron microscopy (SEM) for characterization and carefully examined the relative parameters like response magnitude (sensitivity) and selectivity of SnO2 nano structures with different particle size.

Two-stage epitaxial growth of vertically-aligned SnO 2 nano-rods on(001) ceria

DOE PAGES

Solovyov, Vyacheslav F.; Wu, Li-jun; Rupich, Martin W.; ...

2014-09-20

Growth of high-aspect ratio oriented tin oxide, SnO 2, nano-rods is complicated by a limited choice of matching substrates. We show that a (001) cerium oxide, CeO 2, surface uniquely enables epitaxial growth of tin-oxide nano-rods via a two-stage process. First, (100) oriented nano-wires coat the ceria surface by lateral growth, forming a uniaxially-textured SnO 2 deposit. Second, vertical SnO 2nano-rods nucleate on the deposit by homoepitaxy. We demonstrate growth of vertically oriented 1-2 μm long nano-rods with an average diameter of ≈20 nm.

Scalable fabrication of SnO2 thin films sensitized with CuO islands for enhanced H2S gas sensing performance

NASA Astrophysics Data System (ADS)

Van Toan, Nguyen; Chien, Nguyen Viet; Van Duy, Nguyen; Vuong, Dang Duc; Lam, Nguyen Huu; Hoa, Nguyen Duc; Van Hieu, Nguyen; Chien, Nguyen Duc

2015-01-01

The detection of H2S, an important gaseous molecule that has been recently marked as a highly toxic environmental pollutant, has attracted increasing attention. We fabricate a wafer-scale SnO2 thin film sensitized with CuO islands using microelectronic technology for the improved detection of the highly toxic H2S gas. The SnO2-CuO island sensor exhibits significantly enhanced H2S gas response and reduced operating temperature. The thickness of CuO islands strongly influences H2S sensing characteristics, and the highest H2S gas response is observed with 20 nm-thick CuO islands. The response value (Ra/Rg) of the SnO2-CuO island sensor to 5 ppm H2S is as high as 128 at 200 °C and increases nearly 55-fold compared with that of the bare SnO2 thin film sensor. Meanwhile, the response of the SnO2-CuO island sensor to H2 (250 ppm), NH3 (250 ppm), CO (250 ppm), and LPG (1000 ppm) are low (1.3-2.5). The enhanced gas response and selectivity of the SnO2-CuO island sensor to H2S gas is explained by the sensitizing effect of CuO islands and the extension of electron depletion regions because of the formation of p-n junctions.

Fabrication of hydrogen peroxide biosensor based on Ni doped SnO2 nanoparticles.

PubMed

Lavanya, N; Radhakrishnan, S; Sekar, C

2012-01-01

Ni doped SnO(2) nanoparticles (0-5 wt%) have been prepared by a simple microwave irradiation (2.45 GHz) method. Powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies confirmed the formation of rutile structure with space group (P(42)/mnm) and nanocrystalline nature of the products with spherical morphology. Direct electrochemistry of horseradish peroxidase (HRP)/nano-SnO(2) composite has been studied. The immobilized enzyme retained its bioactivity, exhibited a surface confined, reversible one-proton and one-electron transfer reaction, and had good stability, activity and a fast heterogeneous electron transfer rate. A significant enzyme loading (3.374×10(-10) mol cm(-2)) has been obtained on nano-Ni doped SnO(2) as compared to the bare glassy carbon (GC) and nano-SnO(2) modified surfaces. This HRP/nano-Ni-SnO(2) film has been used for sensitive detection of H(2)O(2) by differential pulse voltammetry (DPV), which exhibited a wider linearity range from 1.0×10(-7) to 3.0×10(-4)M (R=0.9897) with a detection limit of 43 nM. The apparent Michaelis-Menten constant (K(M)(app)) of HRP on the nano-Ni-SnO(2) was estimated as 0.221 mM. This excellent performance of the fabricated biosensor is attributed to large surface-to-volume ratio and Ni doping into SnO(2) which facilitate the direct electron transfer between the redox enzyme and the surface of electrode. Copyright © 2012 Elsevier B.V. All rights reserved.

Microstructural, optical and electrical transport properties of Cd-doped SnO2 nanoparticles

NASA Astrophysics Data System (ADS)

Ahmad, Naseem; Khan, Shakeel; Mohsin Nizam Ansari, Mohd

2018-03-01

We have successfully investigated the structural, optical and dielectric properties of Cd assimilated SnO2 nanoparticles synthesized via very convenient precipitation route. The structural properties were studied by x-ray diffraction method (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy. As-synthesized samples in the form of powder were examined for its morphology and average particle size by Transmission electron microscopy (TEM). The optical properties were studied by diffuse reflectance spectroscopy. Dielectric properties such that complex dielectric constant and ac conductivity were investigated by LCR meter. Average crystallite size calculated by XRD and average particle size obtained from TEM were found to be consistent and below 50 nm for all samples. The optical band gap of as-synthesized powder samples from absorption study was found in the range of 3.76 to 3.97 eV. The grain boundary parameters such that Rgb, Cgb and τ were evaluated using impedance spectroscopy.

Label-free SnO2 nanowire FET biosensor for protein detection

NASA Astrophysics Data System (ADS)

Jakob, Markus H.; Dong, Bo; Gutsch, Sebastian; Chatelle, Claire; Krishnaraja, Abinaya; Weber, Wilfried; Zacharias, Margit

2017-06-01

Novel tin oxide field-effect-transistors (SnO2 NW-FET) for pH and protein detection applicable in the healthcare sector are reported. With a SnO2 NW-FET the proof-of-concept of a bio-sensing device is demonstrated using the carrier transport control of the FET channel by a (bio-) liquid modulated gate. Ultra-thin Al2O3 fabricated by a low temperature atomic layer deposition (ALD) process represents a sensitive layer to H+ ions safeguarding the nanowire at the same time. Successful pH sensitivity is demonstrated for pH ranging from 3 to 10. For protein detection, the SnO2 NW-FET is functionalized with a receptor molecule which specifically interacts with the protein of interest to be detected. The feasibility of this approach is demonstrated via the detection of a biotinylated protein using a NW-FET functionalized with streptavidin. An immediate label-free electronic read-out of the signal is shown. The well-established Enzyme-Linked Immunosorbent Assay (ELISA) method is used to determine the optimal experimental procedure which would enable molecular binding events to occur while being compatible with a final label-free electronic read-out on a NW-FET. Integration of the bottom-up fabricated SnO2 NW-FET pH- and biosensor into a microfluidic system (lab-on-a-chip) allows the automated analysis of small volumes in the 400 μl range as would be desired in portable on-site point-of-care (POC) devices for medical diagnosis.

Vacancy-Induced Ferromagnetism in SnO2 Nanocrystals: A Positron Annihilation Study

NASA Astrophysics Data System (ADS)

Chen, Zhi-Yuan; Chen, Zhi-Quan; Pan, Rui-Kun; Wang, Shao-Jie

2013-02-01

SnO2 nanopowders were pressed into pellets and annealed in air from 100 to 1400°C. Both XRD and Raman spectroscopy confirm that all annealed samples were single phase with a tetragonal rutile structure. Annealing induces an increase in the SnO2 grain size from 30 to 83 nm. Positron annihilation measurements reveal vacancy defects in the grain boundary region, and the interfacial defects remain stable after annealing below 400°C, then they are gradually recovered with increasing annealing temperature up to 1200°C. Room temperature ferromagnetism was observed for SnO2 nanocrystals annealed below 1200°C, and the magnetization decreases continuously with increasing annealing temperature. However, the ferromagnetism disappears at 1200°C annealing. This shows good coincidence with the recovery of interfacial defects in the nanocrystals, suggesting that the ferromagnetism is probably induced by vacancy defects in the interface region.

Identification of vacancy defect complexes in transparent semiconducting oxides ZnO, In2O3 and SnO2.

PubMed

Makkonen, Ilja; Korhonen, Esa; Prozheeva, Vera; Tuomisto, Filip

2016-06-08

Positron annihilation spectroscopy, when combined with supporting high-quality modeling of positron states and annihilation in matter, is a powerful tool for detailed defect identification of vacancy-type defects in semiconductors and oxides. Here we demonstrate that the Doppler broadening of the positron annihilation radiation is a very sensitive means for observing the oxygen environment around cation vacancies, the main open-volume defects trapping positrons in measurements made for transparent semiconducting oxides. Changes in the positron annihilation signal due to external manipulation such as irradiation and annealing can be correlated with the associated changes in the sizes of the detected vacancy clusters. Our examples for ZnO, In2O3 and SnO2 demonstrate that oxygen vacancies in oxides can be detected directly using positron annihilation spectroscopy when they are complexed with cation vacancies.

Identification of vacancy defect complexes in transparent semiconducting oxides ZnO, In2O3 and SnO2

NASA Astrophysics Data System (ADS)

Makkonen, Ilja; Korhonen, Esa; Prozheeva, Vera; Tuomisto, Filip

2016-06-01

Positron annihilation spectroscopy, when combined with supporting high-quality modeling of positron states and annihilation in matter, is a powerful tool for detailed defect identification of vacancy-type defects in semiconductors and oxides. Here we demonstrate that the Doppler broadening of the positron annihilation radiation is a very sensitive means for observing the oxygen environment around cation vacancies, the main open-volume defects trapping positrons in measurements made for transparent semiconducting oxides. Changes in the positron annihilation signal due to external manipulation such as irradiation and annealing can be correlated with the associated changes in the sizes of the detected vacancy clusters. Our examples for ZnO, In2O3 and SnO2 demonstrate that oxygen vacancies in oxides can be detected directly using positron annihilation spectroscopy when they are complexed with cation vacancies.

Strain-induced optical band gap variation of SnO 2 films

DOE PAGES

Rus, Stefania Florina; Ward, Thomas Zac; Herklotz, Andreas

2016-06-29

In this paper, thickness dependent strain relaxation effects are utilized to study the impact of crystal anisotropy on the optical band gap of epitaxial SnO 2 films grown by pulsed laser deposition on (0001)-oriented sapphire substrates. An X-ray diffraction analysis reveals that all films are under tensile biaxial in-plane strain and that strain relaxation occurs with increasing thickness. Variable angle spectroscopic ellipsometry shows that the optical band gap of the SnO 2 films continuously increases with increasing film thickness. This increase in the band gap is linearly related to the strain state of the films, which indicates that the mainmore » origin of the band gap change is strain relaxation. The experimental observation is in excellent agreement with results from density functional theory for biaxial in-plane strain. Our research demonstrates that strain is an effective way to tune the band gap of SnO 2 films and suggests that strain engineering is an appealing route to tailor the optical properties of oxide semiconductors.« less

Facile fabrication of all-solid-state SnO2/NiCo2O4 biosensor for self-powered glucose detection

NASA Astrophysics Data System (ADS)

Cai, Bin; Mao, Weiwei; Ye, Zhizhen; Huang, Jingyun

2016-09-01

With increasing attention on daily diabetes management, we develop an all-solid-state self-powered glucose biosensor, with simultaneous solar energy conversion, electrochemical energy storage and glucose sensing. The SnO2 nanosheet arrays are used to obtain photogenerated electron-hole pairs, and rhombus-shaped NiCo2O4 nanorod arrays are developed for solar energy storage. A stable open circuit voltage ~0.58 V is obtained after being fully charged, which is a suitable voltage for the oxidation of glucose. The biosensor can work under two different modes without any external bias voltage, and both show large linear range and excellent selectivity. Under the sunlight, photocurrent shows a sensitive decrease upon different glucose additions. Meanwhile, in the dark condition, the open circuit voltage of the charged biosensor also exhibits a corresponding response to glucose.

SNO+ Scintillator Purification and Assay

NASA Astrophysics Data System (ADS)

Ford, R.; Chen, M.; Chkvorets, O.; Hallman, D.; Vázquez-Jáuregui, E.

2011-04-01

We describe the R&D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g/L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation and steam stripping at a flow rate of 19 LPM. While the detector is operational the scintillator can be recirculated at 150 LPM (full detector volume in 4 days) to provide repurification as necessary by either water extraction (for Ra, K, Bi) or by functional metal scavenger columns (for Pb, Ra, Bi, Ac, Th) followed by steam stripping to remove noble gases and oxygen (Rn, O2, Kr, Ar). The metal scavenger columns also provide a method for scintillator assay for ex-situ measurement of the U and Th chain radioactivity. We have developed "natural" radioactive spikes of Pb and Ra in LAB and use these for purification testing. Lastly, we present the planned operating modes and purification strategies and the plant specifications and design.

Junction Quality of SnO2-Based Perovskite Solar Cells Investigated by Nanometer-Scale Electrical Potential Profiling.

PubMed

Xiao, Chuanxiao; Wang, Changlei; Ke, Weijun; Gorman, Brian P; Ye, Jichun; Jiang, Chun-Sheng; Yan, Yanfa; Al-Jassim, Mowafak M

2017-11-08

Electron-selective layers (ESLs) and hole-selective layers (HSLs) are critical in high-efficiency organic-inorganic lead halide perovskite (PS) solar cells for charge-carrier transport, separation, and collection. We developed a procedure to assess the quality of the ESL/PS junction by measuring potential distribution on the cross section of SnO 2 -based PS solar cells using Kelvin probe force microscopy. Using the potential profiling, we compared three types of cells made of different ESLs but otherwise having an identical device structure: (1) cells with PS deposited directly on bare fluorine-doped SnO 2 (FTO)-coated glass; (2) cells with an intrinsic SnO 2 thin layer on the top of FTO as an effective ESL; and (3) cells with the SnO 2 ESL and adding a self-assembled monolayer (SAM) of fullerene. The results reveal two major potential drops or electric fields at the ESL/PS and PS/HSL interfaces. The electric-field ratio between the ESL/PS and PS/HSL interfaces increased in devices as follows: FTO < SnO 2 -ESL < SnO 2 + SAM; this sequence explains the improvements of the fill factor (FF) and open-circuit voltage (V oc ). The improvement of the FF from the FTO to SnO 2 -ESL cells may result from the reduction in voltage loss at the PS/HSL back interface and the improvement of V oc from the prevention of hole recombination at the ESL/PS front interface. The further improvements with adding an SAM is caused by the defect passivation at the ESL/PS interface, and hence, improvement of the junction quality. These nanoelectrical findings suggest possibilities for improving the device performance by further optimizing the SnO 2 -based ESL material quality and the ESL/PS interface.

Two-stage epitaxial growth of vertically-aligned SnO2 nano-rods on (001) ceria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solovyov, VF; Wu, LJ; Rupich, MW

2014-12-15

Growth of high-aspect ratio oriented tin oxide, SnO2, nano-rods is complicated by a limited choice of matching substrates. We show that a (001) cerium oxide, CeO2, surface uniquely enables epitaxial growth of tin-oxide nano-rods via a two-stage process. First, (100) oriented nano-wires coat the ceria surface by lateral growth, forming a uniaxially-textured SnO2 deposit. Second, vertical SnO2 nano-rods nucleate on the deposit by homoepitaxy. We demonstrate growth of vertically oriented 1-2 mu m long nano-rods with an average diameter of approximate to 20 nm. 2014 Elsevier B.V. All rights reserved.

Synthesis of porous SnO2 nanocubes via selective leaching and enhanced gas-sensing properties

NASA Astrophysics Data System (ADS)

Li, Yining; Wei, Qi; Song, Peng; Wang, Qi

2016-01-01

Porous micro-/nanostructures are of great interest in many current and emerging areas of technology. In this paper, porous SnO2 nanocubes have been successfully fabricated via a selective leaching strategy using CoSn(OH)6 as precursor. The structure and morphology of as-prepared samples were investigated by several techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric and differential scanning calorimeter analysis (TG⿿DSC), transmission electron microscopy (TEM) and N2 adsorption⿿desorption analyses. On the basis of those characterizations, the mechanism for the formation of porous SnO2 nanocubes has been proposed. Owing to the well-defined and uniform porous structures, porous SnO2 nanocubes possessing more adsorbent amount of analytic gas and accelerate the transmission speed so as to enhance the gas-sensing properties. Gas sensing investigation showed that the sensor based on porous SnO2 nanocubes exhibited high response, short response⿿recovery times and good selectivity to ethanol gas.

Negative feedback regulation of TGF-beta signaling by the SnoN oncoprotein.

PubMed

Stroschein, S L; Wang, W; Zhou, S; Zhou, Q; Luo, K

1999-10-22

Smad proteins mediate transforming growth factor-beta (TGF-beta) signaling to regulate cell growth and differentiation. The SnoN oncoprotein was found to interact with Smad2 and Smad4 and to repress their abilities to activate transcription through recruitment of the transcriptional corepressor N-CoR. Immediately after TGF-beta stimulation, SnoN is rapidly degraded by the nuclear accumulation of Smad3, allowing the activation of TGF-beta target genes. By 2 hours, TGF-beta induces a marked increase in SnoN expression, resulting in termination of Smad-mediated transactivation. Thus, SnoN maintains the repressed state of TGF-beta-responsive genes in the absence of ligand and participates in negative feedback regulation of TGF-beta signaling.

Fabrication of a transparent ultraviolet detector by using n-type Ga2O3 and p-type Ga-doped SnO2 core-shell nanowires.

PubMed

Hsu, Cheng-Liang; Lu, Ying-Ching

2012-09-21

This study investigates the feasibility of synthesizing high-density transparent Ga(2)O(3)/SnO(2):Ga core-shell nanowires on a sapphire substrate at 1000 °C by VLS. The doping Ga concentrations are 0.46, 1.07, 2.30 and 17.53 atomic%. The XRD spectrum and HR-TEM reveal Ga(2)O(3) and SnO(2) as having monoclinic and tetragonal rutile structures, respectively. Experimental results indicate that the XRD peak shift of SnO(2) to a larger angle increases with the increasing amount of Ga doping. According to the CL spectrum, SnO(2) and Ga(2)O(3) peak at approximately 528-568 nm and 422-424 nm, respectively. The maximum quantum efficiency of Ga(2)O(3)/SnO(2):Ga core-shell nanowires is around 0.362%. The UV light on-off current contrast ratio of Ga(2)O(3)/SnO(2):Ga core-shell nanowires is around 1066.7 at a bias of 5 V. Moreover, the dynamic response of Ga(2)O(3)/SnO(2):Ga core-shell nanowires has an on-off current contrast ratio of around 16. Furthermore, the Ga(2)O(3) region functions similar to a capacitor and continues to accumulate SnO(2):Ga excited electrons under UV light exposure.

A novel flexible room temperature ethanol gas sensor based on SnO2 doped poly-diallyldimethylammonium chloride.

PubMed

Zhan, Shuang; Li, Dongmei; Liang, Shengfa; Chen, Xin; Li, Xia

2013-04-02

A novel flexible room temperature ethanol gas sensor was fabricated and demonstrated in this paper. The polyimide (PI) substrate-based sensor was formed by depositing a mixture of SnO2 nanopowder and poly-diallyldimethylammonium chloride (PDDAC) on as-patterned interdigitated electrodes. PDDAC acted both as the binder, promoting the adhesion between SnO2 and the flexible PI substrate, and the dopant. We found that the response of SnO2-PDDAC sensor is significantly higher than that of SnO2 alone, indicating that the doping with PDDAC effectively improved the sensor performance. The SnO2-PDDAC sensor has a detection limit of 10 ppm at room temperature and shows good selectivity to ethanol, making it very suitable for monitoring drunken driving. The microstructures of the samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier transform infrared spectra (FT-IR), and the sensing mechanism is also discussed in detail.

Junction Quality of SnO 2-Based Perovskite Solar Cells Investigated by Nanometer-Scale Electrical Potential Profiling

DOE PAGES

Xiao, Chuanxiao; Wang, Changlei; Ke, Weijun; ...

2017-10-13

Electron-selective layers (ESLs) and hole-selective layers (HSLs) are critical in high-efficiency organic-inorganic lead halide perovskite (PS) solar cells for charge-carrier transport, separation, and collection. We developed a procedure to assess the quality of the ESL/PS junction by measuring potential distribution on cross-section of SnO 2-based perovskite solar cells using Kelvin probe force microscopy. Using the potential profiling, we compared three types of cells made of different ESLs but otherwise having identical device structure: cells with PS deposited directly on bare fluorine-doped SnO 2 (FTO)-coated glass; cells with an intrinsic SnO 2 thin layer on the top of FTO as anmore » effective ESL; and cells with the SnO2 ESL and adding a self-assembled monolayer (SAM) of fullerene. The results reveal two major potential drops or electric fields at the ESL/PS and PS/HSL interfaces. The electric-field ratio between the ESL/PS and PS/HSL interfaces increased in devices as follows: FTO < SnO 2-ESL < SnO 2+SAM; this sequence explains the improvements of fill factor (FF) and open-circuit voltage ( V oc). The improvement of FF from the FTO to SnO 2-ESL cells may result from the reduction in voltage lose at the PS/HSL back interface and the improvement of V oc from the prevention of hole recombination at the ESL/PS front interface. The further improvements with adding a SAM is caused by the defect passivation at the ESL/PS interface, and hence, improvement of the junction quality. Furthermore, these nanoelectrical findings suggest possibilities for improving the device performance by further optimizing the SnO2-based ESL material quality and the ESL/PS interface.« less

Junction Quality of SnO 2-Based Perovskite Solar Cells Investigated by Nanometer-Scale Electrical Potential Profiling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Chuanxiao; Wang, Changlei; Ke, Weijun

Electron-selective layers (ESLs) and hole-selective layers (HSLs) are critical in high-efficiency organic-inorganic lead halide perovskite (PS) solar cells for charge-carrier transport, separation, and collection. We developed a procedure to assess the quality of the ESL/PS junction by measuring potential distribution on cross-section of SnO 2-based perovskite solar cells using Kelvin probe force microscopy. Using the potential profiling, we compared three types of cells made of different ESLs but otherwise having identical device structure: cells with PS deposited directly on bare fluorine-doped SnO 2 (FTO)-coated glass; cells with an intrinsic SnO 2 thin layer on the top of FTO as anmore » effective ESL; and cells with the SnO2 ESL and adding a self-assembled monolayer (SAM) of fullerene. The results reveal two major potential drops or electric fields at the ESL/PS and PS/HSL interfaces. The electric-field ratio between the ESL/PS and PS/HSL interfaces increased in devices as follows: FTO < SnO 2-ESL < SnO 2+SAM; this sequence explains the improvements of fill factor (FF) and open-circuit voltage ( V oc). The improvement of FF from the FTO to SnO 2-ESL cells may result from the reduction in voltage lose at the PS/HSL back interface and the improvement of V oc from the prevention of hole recombination at the ESL/PS front interface. The further improvements with adding a SAM is caused by the defect passivation at the ESL/PS interface, and hence, improvement of the junction quality. Furthermore, these nanoelectrical findings suggest possibilities for improving the device performance by further optimizing the SnO2-based ESL material quality and the ESL/PS interface.« less

Morphology-controlled construction of hierarchical hollow hybrid SnO2@TiO2 nanocapsules with outstanding lithium storage

PubMed Central

Zhou, Linzong; Guo, Hong; Li, Tingting; Chen, Weiwei; Liu, Lixiang; Qiao, Jinli; Zhang, Jiujun

2015-01-01

A novel synthesis containing microwave-assisted HCl etching reaction and precipitating reaction is employed to prepare hierarchical hollow SnO2@TiO2 nanocapsules for anode materials of Li-ion batteries. The intrinsic hollow nanostructure can shorten the lengths for both ionic and electronic transport, enlarge the electrode surface areas, and improving accommodation of the anode volume change during Li insertion/extraction cycling. The hybrid multi-elements in this material allow the volume change to take place in a stepwise manner during electrochemical cycling. In particular, the coating of TiO2 onto SnO2 can enhance the electronic conductivity of hollow SnO2 electrode. As a result, the as-prepared SnO2@TiO2 nanocapsule electrode exhibits a stably reversible capacity of 770 mA hg−1 at 1 C, and the capacity retention can keep over 96.1% after 200 cycles even at high current rates. This approach may shed light on a new avenue for the fast synthesis of hierarchical hollow nanocapsule functional materials for energy storage, catalyst and other new applications. PMID:26482415

Bio-green synthesis of Fe doped SnO2 nanoparticle thin film

NASA Astrophysics Data System (ADS)

Gattu, Ketan P.; Ghule, Kalyani; Huse, Nanasaheb P.; Dive, Avinash S.; Bagul, Sagar B.; Digraskar, Renuka V.; Sharma, Ramphal; Ghule, Anil V.

2017-05-01

Herein Fe doped SnO2 nanoparticles have been synthesized using simple, cost effective and ecofriendly biosynthesis method, in which remnant water (ideally kitchen waste) collected from soaked Bengal gram beans (Cicer arietinum L.) was used. This extract consists of different bio-molecules which acted as complexing as well as capping agents for synthesis of Fe-doped SnO2 nanoparticles. The X-ray powder diffraction (XRD) and Field-emission scanning electron microscopy (FE-SEM) revealed uniform size distribution with the average size of 6 nm and confirmed the formation of rutile structure with space group (P42/mnm) and nanocrystalline nature of the products with spherical morphology. Further, the gas sensing properties of the materials have been studied in comparison with other gases. The reported gas sensing results are promising, which suggest that the Fe-dopant is a promising noble metal additives to fabricate low cost SnO2 based sensor.

Enhanced lithium storage in Fe2O3-SnO2-C nanocomposite anode with a breathable structure

NASA Astrophysics Data System (ADS)

Rahman, Md Mokhlesur; Glushenkov, Alexey M.; Ramireddy, Thrinathreddy; Tao, Tao; Chen, Ying

2013-05-01

A novel nanocomposite architecture of a Fe2O3-SnO2-C anode, based on clusters of Fe2O3 and SnO2 nanoparticles dispersed along the conductive chains of Super P Li™ carbon black (Timcal Ltd.), is presented as a breathable structure in this paper for lithium-ion batteries. The synthesis of the nanocomposite is achieved by combining a molten salt precipitation process and a ball milling method for the first time. The crystalline structure, morphology, and electrochemical characterization of the synthesised product are investigated systematically. Electrochemical results demonstrate that the reversible capacity of the composite anode is 1110 mA h g-1 at a current rate of 158 mA g-1 with only 31% of initial irreversible capacity in the first cycle. A high reversible capacity of 502 mA h g-1 (higher than the theoretical capacity of graphite, ~372 mA h g-1) can be obtained at a high current rate of 3950 mA g-1. The electrochemical performance is compared favourably with those of Fe2O3-SnO2 and Fe2O3-SnO2-C composite anodes for lithium-ion batteries reported in the literature. This work reports a promising method for the design and preparation of nanocomposite electrodes for lithium-ion batteries.A novel nanocomposite architecture of a Fe2O3-SnO2-C anode, based on clusters of Fe2O3 and SnO2 nanoparticles dispersed along the conductive chains of Super P Li™ carbon black (Timcal Ltd.), is presented as a breathable structure in this paper for lithium-ion batteries. The synthesis of the nanocomposite is achieved by combining a molten salt precipitation process and a ball milling method for the first time. The crystalline structure, morphology, and electrochemical characterization of the synthesised product are investigated systematically. Electrochemical results demonstrate that the reversible capacity of the composite anode is 1110 mA h g-1 at a current rate of 158 mA g-1 with only 31% of initial irreversible capacity in the first cycle. A high reversible capacity of 502 m

Correlation between emission property and concentration of Sn2+ center in the SnO-ZnO-P2O5 glass.

PubMed

Masai, Hirokazu; Tanimoto, Toshiro; Fujiwara, Takumi; Matsumoto, Syuji; Tokuda, Yomei; Yoko, Toshinobu

2012-12-03

The authors report on the correlation between the photoluminescence (PL) property and the SnO amount in SnO-ZnO-P2O5 (SZP) glass. In the PL excitation (PLE) spectra of the SZP glass containing Sn2+ emission center, two S1 states, one of which is strongly affected by SnO amount, are assumed to exist. The PLE band closely correlates with the optical band edge originating from Sn2+ species, and they both largely red-shifts with increasing amount of SnO. The emission decay time of the SZP glass decreased with increasing amount of SnO and the internal quantum efficiencies of the SZP glasses containing 1~5 mol% of SnO are comparable to that of MgWO4. It is expected that the composition-dependent S1 state (the lower energy excitation band) governs the quantum efficiency of the SZP glasses.

Hierarchical nanostructured WO3-SnO2 for selective sensing of volatile organic compounds

NASA Astrophysics Data System (ADS)

Nayak, Arpan Kumar; Ghosh, Ruma; Santra, Sumita; Guha, Prasanta Kumar; Pradhan, Debabrata

2015-07-01

It remains a challenge to find a suitable gas sensing material that shows a high response and shows selectivity towards various gases simultaneously. Here, we report a mixed metal oxide WO3-SnO2 nanostructured material synthesized in situ by a simple, single-step, one-pot hydrothermal method at 200 °C in 12 h, and demonstrate its superior sensing behavior towards volatile organic compounds (VOCs) such as ammonia, ethanol and acetone. SnO2 nanoparticles with controlled size and density were uniformly grown on WO3 nanoplates by varying the tin precursor. The density of the SnO2 nanoparticles on the WO3 nanoplates plays a crucial role in the VOC selectivity. The responses of the present mixed metal oxides are found to be much higher than the previously reported results based on single/mixed oxides and noble metal-doped oxides. In addition, the VOC selectivity is found to be highly temperature-dependent, with optimum performance obtained at 200 °C, 300 °C and 350 °C for ammonia, ethanol and acetone, respectively. The present results on the cost-effective noble metal-free WO3-SnO2 sensor could find potential application in human breath analysis by non-invasive detection.It remains a challenge to find a suitable gas sensing material that shows a high response and shows selectivity towards various gases simultaneously. Here, we report a mixed metal oxide WO3-SnO2 nanostructured material synthesized in situ by a simple, single-step, one-pot hydrothermal method at 200 °C in 12 h, and demonstrate its superior sensing behavior towards volatile organic compounds (VOCs) such as ammonia, ethanol and acetone. SnO2 nanoparticles with controlled size and density were uniformly grown on WO3 nanoplates by varying the tin precursor. The density of the SnO2 nanoparticles on the WO3 nanoplates plays a crucial role in the VOC selectivity. The responses of the present mixed metal oxides are found to be much higher than the previously reported results based on single/mixed oxides and

Experimental Study of Acid Treatment Toward Characterization of Structural, Optical, and Morphological Properties of TiO2-SnO2 Composite Thin Film

NASA Astrophysics Data System (ADS)

Fajar, M. N.; Hidayat, R.; Triwikantoro; Endarko

2018-04-01

The TiO2-SnO2 thin film with single and double-layer structure has successfully synthesized on FTO (Fluorine-doped Tin Oxide) substrate using the screen printing technique. The structural, optical, and morphological properties of the film were investigated by XRD, UV-Vis, and SEM, respectively. The results showed that the single and double-layer structure of TiO2-SnO2 thin film has mixed phase with a strong formation of casseritte phase. The acid treatment effect on TiO2-SnO2 thin film decreases the peak intensity of anatase phase formation and thin film’s absorbance values. The morphological study is also revealed that the single layer TiO2-SnO2 thin film had a more porous nature and decreased particle size distribution after acid treatment, while the double-layer TiO2-SnO2 thin film Eroded due to acid treatment.

Characterization of SnO2 Film with Al-Zn Doping Using Sol-Gel Dip Coating Techniques

NASA Astrophysics Data System (ADS)

Doyan, A.; Susilawati; Ikraman, N.; Taufik, M.

2018-04-01

Sn1-2x AlxZnxO2 film has been developed using sol-gel dip coating technique. The materials SnCl2.2H2O, AlCl3 and ZnCl2 dissolved in water and ethanol with 5:95 volume ratio. Variations dopant concentration x = 0.000, 0.005, 0.0025, and 0.050. The film was grown with sol concentration 0.4 M, the withdrawal speed of 12 cm/min and sintering at 600 °C for 30 minutes. The characteristics Sn1-2x AlxZnxO2 films with various doping concentration phase were characterized by XRD. The morphological characteristics and the composition of the constituent elements of the film were characterized by SEM-EDX. The characteristics of the shape, structure, and size of the particles were characterized by TEM. The XRD results show that all films have a tetragonal SnO2 rutile phase without any secondary phase with an average particle size in the range 5.14 – 2.09 nm. The SEM results show that the film grown has a smooth morphology with a striped texture (x = 0.00), and there is a crack (x = 0.050). The EDX results show that the composition and distribution of the constituent elements of the film are uniformly distributed. TEM results show that the particle films has tetragonal rutile structure, orthorhombic and amorphous with a spherical shape.

Synthesis of Stable Interfaces on SnO2 Surfaces for Charge-Transfer Applications

NASA Astrophysics Data System (ADS)

Benson, Michelle C.

The commercial market for solar harvesting devices as an alternative energy source requires them to be both low-cost and efficient to replace or reduce the dependence on fossil fuel burning. Over the last few decades there has been promising efforts towards improving solar devices by using abundant and non-toxic metal oxide nanomaterials. One particular metal oxide of interest has been SnO2 due to its high electron mobility, wide-band gap, and aqueous stability. However SnO2 based solar cells have yet to reach efficiency values of other metal oxides, like TiO2. The advancement of SnO2 based devices is dependent on many factors, including improved methods of surface functionalization that can yield stable interfaces. This work explores the use of a versatile functionalization method through the use of the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The CuAAC reaction is capable of producing electrochemically, photochemically, and electrocatalytically active surfaces on a variety of SnO2 materials. The resulting charge-transfer characteristics were investigated as well as an emphasis on understanding the stability of the resulting molecular linkage. We determined the CuAAC reaction is able to proceed through both azide-modified and alkyne-modified surfaces. The resulting charge-transfer properties showed that the molecular tether was capable of supporting charge separation at the interface. We also investigated the enhancement of electron injection upon the introduction of an ultra-thin ZrO2 coating on SnO2. Several complexes were used to fully understand the charge-transfer capabilities, including model systems of ferrocene and a ruthenium coordination complex, a ruthenium mononuclear water oxidation catalyst, and a commercial ruthenium based dye.

SnO2 Nanostructures: Effect of Processing Parameters on Their Structural and Functional Properties

NASA Astrophysics Data System (ADS)

Dontsova, Tetiana A.; Nagirnyak, Svitlana V.; Zhorov, Vladyslav V.; Yasiievych, Yuriy V.

2017-05-01

Zero- and 1D (one-dimensional) tin (IV) oxide nanostructures have been synthesized by thermal evaporation method, and a comparison of their morphology, crystal structure, sorption properties, specific surface area, as well as electrical characteristics has been performed. Synthesized SnO2 nanomaterials were studied by X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM), N2 sorption/desorption technique, IR spectroscopy and, in addition, their current-voltage characteristics have also been measured. The single crystalline structures were obtained both in case of 0D (zero-dimensional) SnO2 powders and in case of 0D nanofibers, as confirmed by electron diffraction of TEM. It was found that SnO2 synthesis parameters significantly affect materials' properties by contributing to the difference in morphology, texture formation, changes in IR spectra of 1D structure as compared to 0D powders, increases in the specific surface area of nanofibers, and the alteration of current-voltage characteristics 0D and 1D SnO2 nanostructures. It was established that gas sensors utilizing of 1D nanofibers significantly outperform those based on 0D powders by providing higher specific surface area and ohmic I-V characteristics.

Structural, Optical and Ethanol Sensing Properties of Dy-Doped SnO2 Nanoparticles

NASA Astrophysics Data System (ADS)

Shaikh, F. I.; Chikhale, L. P.; Nadargi, D. Y.; Mulla, I. S.; Suryavanshi, S. S.

2018-04-01

We report a facile co-precipitation synthesis of dysprosium (Dy3+) doped tin oxide (SnO2) thick films and their use as gas sensors. The doping percentage (Dy3+) was varied from 1 mol.% to 4 mol.% with the step of 1 mol.%. As-produced material with varying doping levels were sintered in air; and by using a screen printing technique, their thick films were developed. Prior to sensing performance investigations, the films were examined for structural, morphological and compositional properties using x-ray diffraction, a field emission scanning electron microscope, a transmission electron microscope, selected area electron diffraction, energy dispersive analysis by x-rays, Fourier transform infrared spectroscopy and Raman spectroscopic techniques. The structural analyses revealed formation of single phase nanocrystalline material with tetragonal rutile structure of SnO2. The morphological analyses confirmed the nanocrystalline porous morphology of as-developed material. Elemental analysis defined the composition of material in accordance with the doping concentration. The produced sensor material exhibited good response towards different reducing gases (acetone, ethanol, LPG, and ammonia) at different operating temperatures. The present study confirms that the Dy3+ doping in SnO2 enhances the response towards ethanol with reduction in operating temperature. Particularly, 3 mol.% Dy3+ doped sensor exhibited the highest response (˜ 92%) at an operating temperature of 300°C with better selectivity, fast response (˜ 13 s) and recovery (˜ 22 s) towards ethanol.

Aminoacid N-substituted 1,4,7-triazacyclononane and 1,4,7,10-tetraazacyclododecane Zn2+, Cd2+ and Cu2+ complexes. A preparative, potentiometric titration and NMR spectroscopic study.

PubMed

Plush, Sally E; Lincoln, Stephen F; Wainwright, Kevin P

2004-05-07

The pK(a)s and Zn2+, Cd2+ and Cu2+ complexation constants (K) for 1,4,7-tris[(2''S)-acetamido-2''-(methyl-3''-phenylpropionate)]-1,4,7-triazacyclononane, 1, 1,4,7-tris[(2''S)-acetamido-2''-(1''-carboxy-3''-phenylpropane)]-1,4,7-triazacyclononane, H(3)2, 1,4,7-tris[(2''S)-acetamido-2''-(methyl-3''-(1H-3-indolyl)propionate)]-1,4,7-triazacyclononane, 3, and 1,4,7,10-tetrakis[(2''S)-acetamido-2''-(methyl-3''-phenylpropionate)]-1,4,7,10-tetraazacyclododecane, 4, 1,4,7,10-tetrakis[(2''S)-acetamido-2''-(1''-carboxy-3''-phenylpropane)]-1,4,7,10-tetraazacyclododecane, H(4)5, in 20 : 80 v/v water-methanol solution are reported. The pK(a)s within the potentiometric detection range for H(3)1(3+) = 8.69 and 3.59, for H(6)2(3+) = 9.06, 6.13, 4.93 and 4.52, H(3)3(3+) = 8.79 and 3.67, H(4)4(4+) = 8.50, 5.62 and 3.77 and for H(8)5(4+) = 9.89, 7.06, 5.53, 5.46, 4.44 and 4.26 where each tertiary amine nitrogen is protonated. The complexes of 1: [Zn(1)]2+(9.00), [Cd(1)]2+ (6.49), [Cd(H1)]3+ (4.54) and [Cu(1)]2+ (10.01) are characterized by the log(K/dm3 mol(-1)) values shown in parentheses. Analogous complexes are formed by 3 and 4: [Zn(3)]2+ (10.19), [Cd(3)]2+ (8.54), [Cu(3)]2+ (10.77), [Zn(4)]2+ (11.41) [Cd(4)]2+ (9.16), [Cd(H4)]3+ (6.16) and [Cu(4)]2+ (11.71). The tricarboxylic acid H(3)2 generates a greater variety of complexes as exemplified by: [Zn(2)-] (10.68) [Zn(H2)] (6.60) [Zn(H(2)2)+] (5.15), [Cd(2)](-) (4.99), [Cd(H2)] (4.64), [Cd(H2(2))]+ (3.99), [Cd(H(3)2)]2+ (3.55), [Cu(2)](-) (12.55) [Cu(H2)] (7.66), [Cu(H(2)2)]+ (5.54) and [Cu(2)2](4-) (3.23). The complexes of H(4)5 were insufficiently soluble to study in this way. The 1H and 13C NMR spectra of the ligands are consistent with formation of a predominant Zn2+ and Cd2+ Delta or Lambda diastereomer. The preparations of the new pendant arm macrocycles H(3)2, 3, 4 and H(4)5 are reported.

The electrical, optical, structural and thermoelectrical characterization of n- and p-type cobalt-doped SnO 2 transparent semiconducting films prepared by spray pyrolysis technique

NASA Astrophysics Data System (ADS)

Bagheri-Mohagheghi, Mohammad-Mehdi; Shokooh-Saremi, Mehrdad

2010-10-01

The electrical, optical and structural properties of Cobalt (Co) doped SnO 2 transparent semiconducting thin films, deposited by the spray pyrolysis technique, have been studied. The SnO 2:Co films, with different Co-content, were deposited on glass substrates using an aqueous-ethanol solution consisting of tin and cobalt chlorides. X-ray diffraction studies showed that the SnO 2:Co films were polycrystalline only with tin oxide phases and preferential orientations along (1 1 0) and (2 1 1) planes and grain sizes in the range 19-82 nm. Optical transmittance spectra of the films showed high transparency ∼75-90% in the visible region, decreasing with increase in Co-doping. The optical absorption edge for undoped SnO 2 films was found to be 3.76 eV, while for higher Co-doped films shifted toward higher energies (shorter wavelengths) in the range 3.76-4.04 eV and then slowly decreased again to 4.03 eV. A change in sign of the Hall voltage and Seebeck coefficient was observed for a specific acceptor dopant level ∼11.4 at% in film and interpreted as a conversion from n-type to p-type conductivity. The thermoelectric electro-motive force (e.m.f.) of the films was measured in the temperature range 300-500 K and Seebeck coefficients were found in the range from -62 to +499 μVK -1 for various Co-doped SnO 2 films.

Requirement for the SnoN oncoprotein in transforming growth factor beta-induced oncogenic transformation of fibroblast cells.

PubMed

Zhu, Qingwei; Pearson-White, Sonia; Luo, Kunxin

2005-12-01

Transforming growth factor beta (TGF-beta) was originally identified by virtue of its ability to induce transformation of the AKR-2B and NRK fibroblasts but was later found to be a potent inhibitor of the growth of epithelial, endothelial, and lymphoid cells. Although the growth-inhibitory pathway of TGF-beta mediated by the Smad proteins is well studied, the signaling pathway leading to the transforming activity of TGF-beta in fibroblasts is not well understood. Here we show that SnoN, a member of the Ski family of oncoproteins, is required for TGF-beta-induced proliferation and transformation of AKR-2B and NRK fibroblasts. TGF-beta induces upregulation of snoN expression in both epithelial cells and fibroblasts through a common Smad-dependent mechanism. However, a strong and prolonged activation of snoN transcription that lasts for 8 to 24 h is detected only in these two fibroblast lines. This prolonged induction is mediated by Smad2 and appears to play an important role in the transformation of both AKR-2B and NRK cells. Reduction of snoN expression by small interfering RNA or shortening of the duration of snoN induction by a pharmacological inhibitor impaired TGF-beta-induced anchorage-independent growth of AKR-2B cells. Interestingly, Smad2 and Smad3 play opposite roles in regulating snoN expression in both fibroblasts and epithelial cells. The Smad2/Smad4 complex activates snoN transcription by direct binding to the TGF-beta-responsive element in the snoN promoter, while the Smad3/Smad4 complex inhibits it through a novel Smad inhibitory site. Mutations of Smad4 that render it defective in heterodimerization with Smad3, which are found in many human cancers, convert the activity of Smad3 on the snoN promoter from inhibitory to stimulatory, resulting in increased snoN expression in cancer cells. Thus, we demonstrate a novel role of SnoN in the transforming activity of TGF-beta in fibroblasts and also uncovered a mechanism for the elevated SnoN expression in

Multi-yolk-shell SnO2/Co3Sn2@C Nanocubes with High Initial Coulombic Efficiency and Oxygen Reutilization for Lithium Storage.

PubMed

Su, Liwei; Xu, Yawei; Xie, Jian; Wang, Lianbang; Wang, Yuanhao

2016-12-28

The challenging problems of SnO 2 anode material for lithium ion batteries are the poor electronic conductivity and the low oxygen reutilization due to the irreversibility of Li 2 O generated in the initial discharge leading to a theoretical initial Coulombic efficiency (ICE) of only 52.4%. Different from these strategies, this work proposes a novel strategy to level up the oxygen reutilization in SnO 2 by introducing Co 3 Sn 2 nanoalloys which can release Co atoms to reversibly react with Li 2 O instead. According to this protocol, multi-yolk-shell SnO 2 /Co 3 Sn 2 @C nanocubes are designed and successfully prepared using hollow CoSn(OH) 6 nanocubes as precursors followed a hydrothermal carbon coating and calcination treatment. The unique multi-yolk-shell nanostructure offers adequate breathing space for the volumetric deformation during long-term cycling. Moreover, the removal of Li 2 O allows a high electronic conductivity and resultant rate performance. As a result, the efficient reutilization of oxygen enables a high ICE of 71.7% and a reversible capacity of 1003 mA h g -1 after 200 cycles at 100 mA g -1 . Cyclic voltammetry, cycling performance at different voltage windows, and X-ray photoelectron spectroscopy confirm the proposed mechanism. This strategy employing oxygen-poor metals or alloys provides a novel approach to enhance the oxygen reutilization in SnO 2 for higher reversibility.

Mo-doped SnO2 mesoporous hollow structured spheres as anode materials for high-performance lithium ion batteries

NASA Astrophysics Data System (ADS)

Wang, Xuekun; Li, Zhaoqiang; Zhang, Zhiwei; Li, Qun; Guo, Enyan; Wang, Chengxiang; Yin, Longwei

2015-02-01

We designed a facile infiltration route to synthesize mesoporous hollow structured Mo doped SnO2 using silica spheres as templates. It is observed that Mo is uniformly incorporated into SnO2 lattice in the form of Mo6+. The as-prepared mesoporous Mo-doped SnO2 LIBs anodes exhibit a significantly improved electrochemical performance with good cycling stability, high specific capacity and high rate capability. The mesoporous hollow Mo-doped SnO2 sample with 14 at% Mo doping content displays a specific capacity of 801 mA h g-1 after 60 cycles at a current density of 100 mA g-1, about 1.66 times higher than that of the pure SnO2 hollow sample. In addition, even if the current density is as high as 1600 mA g-1 after 60 cycles, it could still retain a stable specific capacity of 530 mA h g-1, exhibiting an extraordinary rate capability. The greatly improved electrochemical performance of the Mo-doped mesoporous hollow SnO2 sample could be attributed to the following factors. The large surface area and hollow structure can significantly enhance structural integrity by acting as mechanical buffer, effectively alleviating the volume changes generated during the lithiation/delithiation process. The incorporation of Mo into the lattice of SnO2 improves charge transfer kinetics and results in a faster Li+ diffusion rate during the charge-discharge process.

Characterization of dSnoN and its relationship to Decapentaplegic signaling in Drosophila.

PubMed

Barrio, Rosa; López-Varea, Ana; Casado, Mar; de Celis, Jose F

2007-06-01

Vertebrate members of the ski/snoN family of proto-oncogenes antagonize TGFbeta and BMP signaling in a variety of experimental situations. This activity of Ski/SnoN proteins is related to their ability to interact with Smads, the proteins acting as key mediators of the transcriptional response to the TGFbeta superfamily members. However, despite extensive efforts to identify the physiological roles of the Ski/SnoN proteins, it is not yet clear whether they participate in regulating Activin and/or BMP signaling during normal development. It is therefore crucial to examine their roles in vivo mostly because of the large number of known Ski/SnoN-interacting proteins and the association between the up-regulation of these genes and cancer progression. Here we characterize the Drosophila homolog to vertebrate ski and snoN genes. The Drosophila dSnoN protein retains the ability of its vertebrate counterparts to antagonize BMP signaling in vivo and in cultured cells. dSnoN does not interfere with Mad phosphorylation but it interacts genetically with Mad, Medea and dSmad2. Mutations in either the Smad2-3 or Smad4 putative binding sites of dSnoN prevent the antagonism of dSnoN towards Dpp signaling, although homozygous flies for these mutations or for a genetic deficiency of the locus are viable and have wings of normal size and pattern.

Ultrasmall SnO2 Nanocrystals: Hot-bubbling Synthesis, Encapsulation in Carbon Layers and Applications in High Capacity Li-Ion Storage

PubMed Central

Ding, Liping; He, Shulian; Miao, Shiding; Jorgensen, Matthew R.; Leubner, Susanne; Yan, Chenglin; Hickey, Stephen G.; Eychmüller, Alexander; Xu, Jinzhang; Schmidt, Oliver G.

2014-01-01

Ultrasmall SnO2 nanocrystals as anode materials for lithium-ion batteries (LIBs) have been synthesized by bubbling an oxidizing gas into hot surfactant solutions containing Sn-oleate complexes. Annealing of the particles in N2 carbonifies the densely packed surface capping ligands resulting in carbon encapsulated SnO2 nanoparticles (SnO2/C). Carbon encapsulation can effectively buffer the volume changes during the lithiation/delithiation process. The assembled SnO2/C thus deliver extraordinarily high reversible capacity of 908 mA·h·g−1 at 0.5 C as well as excellent cycling performance in the LIBs. This method demonstrates the great potential of SnO2/C nanoparticles for the design of high power LIBs. PMID:24732294

Ultrafast recombination dynamics in dye-sensitized SnO 2/TiO 2 core/shell films

DOE PAGES

Gish, Melissa K.; Lapides, Alexander M.; Brennaman, M. Kyle; ...

2016-12-02

In dye-sensitized photoelectrosynthesis cells (DSPECs), molecular chromophores and catalysts are integrated on a semiconductor surface to perform water oxidation or CO 2 reduction after a series of light-induced electron transfer events. Unfortunately, recombination of the charge separated state (CSS) is competitive with productive catalysis. To overcome this major obstacle, implementation of photoanodic core/shell films within these devices improve electrochemical behavior and slow recombination through the introduction of an energetic barrier between the semiconductor core and oxidized species on the surface. In this study, interfacial dynamics are investigated in SnO 2/TiO 2 core/shell films derivatized with a Ru(II)-polypyridyl chromophore ([RuII(bpy)2(4,4'-(PO 3Hmore » 2) 2bpy)] 2+, RuP) using transient absorption methods. Electron injection from the chromophore into the TiO 2 shell occurs within a few picoseconds after photoexcitation. Loss of the oxidized dye through recombination occurs across time scales spanning 10 orders of magnitude. The majority (60%) of charge recombination events occur shortly after injection (τ = 220 ps), while a small fraction (≤20%) of the oxidized chromophores persists for milliseconds. The lifetime of long-lived CSS depends exponentially on shell thickness, suggesting that the injected electrons reside in the SnO 2 core and must tunnel through the TiO 2 shell to recombine with oxidized dyes. While the core/shell architecture extends the lifetime in a small fraction of the CSS, making water oxidation possible, the subnanosecond recombination process has profound implications for the overall efficiencies of DSPECs.« less

Enhanced gas sensing correlated with structural and optical properties of Cs-loaded SnO2 nanofilms

NASA Astrophysics Data System (ADS)

Elia Raine, P. J.; Arun George, P.; Balasundaram, O. N.; Varghese, T.

2016-09-01

The Cs-loaded SnO2 thin films were prepared by the spray pyrolysis technique and were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible spectroscopy, impedance spectroscopy and conductometric method. Investigations based on the structural, optical and electrical properties confirm an enhanced gas sensing potential of cesium-loaded tin oxide films. It is found that the tin oxide thin film doped with 4% Cs with a mean grain size of 20 nm at a deposition temperature of 350 ° C show a maximum sensor response of 97.5% for LPG consistently. It is also observed that the sensor response of Cs-doped SnO2 thin films depends on the dopant concentration and the deposition temperature of the film.

Fabrication of Nanocomposites of SnO2 and MgAl2O4 for Gas Sensing Applications

NASA Astrophysics Data System (ADS)

Nithyavathy, N.; Arunmetha, S.; Vinoth, M.; Sriram, G.; Rajendran, V.

2016-04-01

Simple solid-state and sol-gel routes have been used to synthesize nanocomposites of tin oxide and magnesium aluminate at calcination temperature of 900 K for gas sensing applications. The effects of the surface structure of magnesium aluminate on the gas response for different concentrations of tin oxide addition were investigated for potential use in gas sensors. (SnO2) x doped in small amounts x into magnesium aluminate resulted in three nanocomposite samples MAS0.25, MAS0.50, and MAS0.75 for x = 0.25, 0.50, and 0.75, respectively, plus MgAl2O4 (MA) for x = 0. The response to different pressures of gases such as oxygen (O2), carbon monoxide (CO), and ethanol (C2H5OH) was quantitatively analyzed for all samples at different operating temperatures. The temperature was varied linearly by increasing the supply to a heating pad mounted below the sensor sample, regardless of the gas pressure inside the chamber. All the sample materials showed good response at different gas pressures (1 bar to 2 bar) and operating temperatures (300 K to 600 K). It was noted that the composite samples showed enhanced and fast response to gases, at both lower and higher operating temperatures, with detection of even the smallest change in gas pressure.

Photocatalytic performance of Ag doped SnO2 nanoparticles modified with curcumin

NASA Astrophysics Data System (ADS)

Vignesh, K.; Hariharan, R.; Rajarajan, M.; Suganthi, A.

2013-07-01

Visible light active Ag doped SnO2 nanoparticles modified with curcumin (Cur-Ag-SnO2) have been prepared by a combined precipitation and chemical impregnation route. The optical properties, phase structures and morphologies of the as-prepared nanoparticles were characterized using UV-visible diffuse reflectance spectra (UV-vis-DRS), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The surface area was measured by Brunauer. Emmett. Teller (B.E.T) analysis. Compared to bare SnO2, the surface modified photocatalysts (Ag-SnO2 and Cur-Ag-SnO2) showed a red shift in the visible region. The photocatalytic activity was monitored via the degradation of rose bengal (RB) dye and the results revealed that Cur-Ag-SnO2 shows better photocatalytic activity than that of Ag-SnO2 and SnO2. The superior photocatalytic activity of Cur-Ag-SnO2 could be attributed to the effective electron-hole separation by surface modification. The effect of photocatalyst concentration, initial dye concentration and electron scavenger on the photocatalytic activity was examined in detail. Furthermore, the antifungal activity of the photocatalysts and the reusability of Cur-Ag-SnO2 were tested.

Gas Sensing Properties of ZnO-SnO2 Nanostructures.

PubMed

Chen, Weigen; Li, Qianzhu; Xu, Lingna; Zeng, Wen

2015-02-01

One-dimensional (1D) semiconductor metal oxide nanostructures have attracted increasing attention in electrochemistry, optics, magnetic, and gas sensing fields for the good properties. N-type low dimensional semiconducting oxides such as SnO2 and ZnO have been known for the detection of inflammable or toxic gases. In this paper, we fabricated the ZnO-SnO2 and SnO2 nanoparticles by hydrothermal synthesis. Microstructure characterization was performed using X-ray diffraction (XRD) and surface morphologies for both the pristine and doped samples were observed using field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Then we made thin film gas sensor to study the gas sensing properties of ZnO-SnO2 and SnO2 gas sensor to H2 and CO. A systematic comparison study reveals an enhanced gas sensing performance for the sensor made of SnO2 and ZnO toward H2 and CO over that of the commonly applied undecorated SnO2 nanoparticles. The improved gas sensing properties are attributed to the size of grains and pronounced electron transfer between the compound nanostructures and the absorbed oxygen species as well as to the heterojunctions of the ZnO nanoparticles to the SnO2 nanoparticles, which provide additional reaction rooms. The results represent an advance of compound nanostructures in further enhancing the functionality of gas sensors, and this facile method could be applicable to many sensing materials, offering a new avenue and direction to detect gases of interest based on composite tin oxide nanoparticles.

Fabrication and good ethanol sensing of biomorphic SnO2 with architecture hierarchy of butterfly wings.

PubMed

Song, Fang; Su, Huilan; Han, Jie; Zhang, Di; Chen, Zhixin

2009-12-09

Using super-hydrophobic butterfly wings as templates, we developed an aqueous sol-gel soakage process assisted by ethanol-wetting and followed by calcination to fabricate well-organized porous hierarchical SnO(2) with connective hollow interiors and thin mesoporous walls. The exquisite hierarchical architecture of SnO(2) is faithfully replicated from the lightweight skeleton of butterfly wings at the level from nano- to macro-scales. On the basis of the self-assembly of SnO(2) nanocrystallites with diameter around 7.0 nm, the interconnected tubes (lamellas), the fastigiated hollow tubers (pillars) and the double-layered substrates further construct the biomorphic hierarchical architecture. Benefiting from the small grain size and the unique hierarchical architecture, the biomorphic SnO(2) as an ethanol sensor exhibits high sensitivity (49.8 to 50 ppm ethanol), and fast response/recovery time (11/31 s to 50 ppm ethanol) even at relatively low working temperature (170 degrees C).

Role of Cu in engineering the optical properties of SnO2 nanostructures: Structural, morphological and spectroscopic studies

NASA Astrophysics Data System (ADS)

Kumar, Virender; Singh, Kulwinder; Jain, Megha; Manju; Kumar, Akshay; Sharma, Jeewan; Vij, Ankush; Thakur, Anup

2018-06-01

We have carried out a systematic study to investigate the effect of Cu doping on the optical properties of SnO2 nanostructures synthesized by chemical route. Synthesized nanostructures were characterized using X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), High resolution transmission electron microscopy (HR-TEM), Energy dispersive X-ray spectroscopy, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, UV-visible and Photoluminescence (PL) spectroscopy. The Rietveld refinement analysis of XRD patterns of Cu-doped SnO2 samples confirmed the formation of single phase tetragonal rutile structure, however some localized distortion was observed for 5 mol% Cu-doped SnO2. Crystallite size was found to decrease with increase in dopant concentration. FE-SEM images indicated change in morphology of samples with doping. HR-TEM images revealed that synthesized nanostructures were nearly spherical and average crystallite size was in the range 12-21 nm. Structural defects, crystallinity and size effects on doping were investigated by Raman spectroscopy and results were complemented by FTIR spectroscopy. Optical band gap of samples was estimated from reflectance spectra. We have shown that band gap of SnO2 can be engineered from 3.62 to 3.82 eV by Cu doping. PL emission intensity increased as the doping concentration increased, which can be attributed to the development of defect states in the forbidden transition region of band gap of SnO2 with doping. We have also proposed a band model owing to defect states in SnO2 to explain the observed PL in Cu doped SnO2 nanostructures.

The alcohol-sensing behaviour of SnO2 nanorods prepared by a facile solid state reaction

NASA Astrophysics Data System (ADS)

Gao, F.; Ren, X. P.; Wan, W. J.; Zhao, Y. P.; Li, Y. H.; Zhao, H. Y.

2017-02-01

SnO2 nanorods with the range of 12-85 nm in diameter were fabricated by a facile solid state reaction in the medium of NaCl-KCl mixture at room temperature and calcined at 600, 680, 760 and 840 oC, respectively. The XRD, TEM and XPS were employed to characterize the structure and morphology of the SnO2 nanorods. The influence of the calcination temperature on the gas sensing behaviour of the SnO2 nanorods with different diameter was investigated. The result showed that all the sensors had good response to alcohol. The response of the gracile nanorods prepared at a low calcined temperature demonstrated significantly better than the thick nanorods prepared at a high calcined temperature. The mechanism was attributed to the nonstoichiometric ratio of Sn/O and larger surface area of the gracile nanorods to enhance the oxygen surface adsorption.

Structural, chemical and optical properties of SnO2 NPs obtained by three different synthesis routes

NASA Astrophysics Data System (ADS)

Drzymała, Elżbieta; Gruzeł, Grzegorz; Depciuch, Joanna; Budziak, Andrzej; Kowal, Andrzej; Parlinska-Wojtan, Magdalena

2017-08-01

Polyol (P), chemical precipitation (C) and microwave-assisted (M) syntheses were chosen to produce SnO2 nanoparticles with uniform size and minimum agglomeration. Their structural, chemical and optical properties were investigated using dynamic light scattering (DLS), scanning transmission electron microscopy (STEM), Raman, Fourier Transform Infrared (FTIR) using the Attenuated Total Reflectance (ATR) technique and Ultraviolet-Visible (UV-Vis) spectroscopies. STEM observations showed that the SnO2(P) and SnO2(C) nanoparticles (NPs) are combined into larger agglomerates with heterogeneous thickness, while the microwave-assisted NPs form a uniform thin layer across the TEM grid. The strongest agglomeration of the SnO2(C) NPs, observed by DLS, STEM and UV-Vis is explained by the very moderate amount of water present on the surface of the NPs identified by FTIR spectroscopy. High resolution STEM combined with SAED and X-ray diffraction (XRD) patterns confirmed the crystalline character of the NPs. In the nanoparticles from polyol synthesis, chlorine from the remains of metal precursors during reduction was detected by energy dispersive spectroscopy (EDS), contrary to the NPs obtained by the chemical precipitation and microwave-assisted methods. All three syntheses routes lead to small, 2-10 nm SnO2 NPs, which were the result of the low concentration of Cl ions in the solutions.

Box C/D small nucleolar RNA (snoRNA) U60 regulates intracellular cholesterol trafficking.

PubMed

Brandis, Katrina A; Gale, Sarah; Jinn, Sarah; Langmade, Stephen J; Dudley-Rucker, Nicole; Jiang, Hui; Sidhu, Rohini; Ren, Aileen; Goldberg, Anna; Schaffer, Jean E; Ory, Daniel S

2013-12-13

Mobilization of plasma membrane (PM) cholesterol to the endoplasmic reticulum is essential for cellular cholesterol homeostasis. The mechanisms regulating this retrograde, intermembrane cholesterol transfer are not well understood. Because mutant cells with defects in PM to endoplasmic reticulum cholesterol trafficking can be isolated on the basis of resistance to amphotericin B, we conducted an amphotericin B loss-of-function screen in Chinese hamster ovary (CHO) cells using insertional mutagenesis to identify genes that regulate this trafficking mechanism. Mutant line A1 displayed reduced cholesteryl ester formation from PM-derived cholesterol and increased de novo cholesterol synthesis, indicating a deficiency in retrograde cholesterol transport. Genotypic analysis revealed that the A1 cell line contained one disrupted allele of the U60 small nucleolar RNA (snoRNA) host gene, resulting in haploinsufficiency of the box C/D snoRNA U60. Complementation and mutational studies revealed the U60 snoRNA to be the essential feature from this locus that affects cholesterol trafficking. Lack of alteration in predicted U60-mediated site-directed methylation of 28 S rRNA in the A1 mutant suggests that the U60 snoRNA modulates cholesterol trafficking by a mechanism that is independent of this canonical function. Our study adds to a growing body of evidence for participation of small noncoding RNAs in cholesterol homeostasis and is the first to implicate a snoRNA in this cellular function.

Derivation of force field parameters for SnO2-H2O surface systems from plane-wave density functional theory calculations.

PubMed

Bandura, A V; Sofo, J O; Kubicki, J D

2006-04-27

Plane-wave density functional theory (DFT-PW) calculations were performed on bulk SnO2 (cassiterite) and the (100), (110), (001), and (101) surfaces with and without H2O present. A classical interatomic force field has been developed to describe bulk SnO2 and SnO2-H2O surface interactions. Periodic density functional theory calculations using the program VASP (Kresse et al., 1996) and molecular cluster calculations using Gaussian 03 (Frisch et al., 2003) were used to derive the parametrization of the force field. The program GULP (Gale, 1997) was used to optimize parameters to reproduce experimental and ab initio results. The experimental crystal structure and elastic constants of SnO2 are reproduced reasonably well with the force field. Furthermore, surface atom relaxations and structures of adsorbed H2O molecules agree well between the ab initio and force field predictions. H2O addition above that required to form a monolayer results in consistent structures between the DFT-PW and classical force field results as well.

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Electrochemical properties of SnO2 nanorods as anode materials in lithium-ion battery

NASA Astrophysics Data System (ADS)

Shi, Song-Lin; Liu, Yong-Gang; Zhang, Jing-Yuan; Wang, Tai-Hong

2009-10-01

Well-dispersed SnO2 nanorods with diameter of 4-15 nm and length of 100-200 nm are synthesised through a hydrothermal route and their potential as anode materials in lithium-ion batteries is investigated. The observed initial discharge capacity is as high as 1778 mA·h/g, much higher than the theoretical value of the bulk SnO2 (1494 mA·h/g). During the following 15 cycles, the reversible capacity decreases from 929 to 576 mA·h/g with a fading rate of 3.5% per cycle. The fading mechanism is discussed. Serious capacity fading can be avoided by reducing the cycling voltages from 0.05-3.0 to 0.4-1.2 V. At the end, SnO2 nanorods with much smaller size are synthesized and their performance as anode materials is studied. The size effect on the electrochemical properties is briefly discussed.

Animal Bone Supported SnO2 as Recyclable Photocatalyst for Degradation of Rhodamine B Dye.

PubMed

Wu, Yun; Wang, Hui; Cao, Mengdie; Zhang, Yichi; Cao, Feifei; Zheng, Xinsheng; Hu, Jinfei; Dong, Jiangshan; Xiao, Zhidong

2015-09-01

SnO2 nanoparticles supported on an animal bone which serves as inexpensive and environment-friendly natural products were developed by a facile hydrothermal approach. As a promising photocatalyst, the novel SnO2/porcine bone material exhibited high photocatalytic activity towards the degradation of rhodamine B (RhB) dye under UV-Vis irradiation. About 97.3% of RhB can be effectively decomposed by the catalysis with the SnO2/porcine bone in 90 min, while only 51.5% of RhB can be degraded by pure SnO2 nanoparticles. Moreover, the photocatalytic activity was incremental with the increase of cycle times in previous five cycles. It is mainly because the photocatalyst which has been used for several times possesses a stronger ability of light absorption and utilization compared to the fresh catalyst according to the results of the characterization and relative experiments. It is noteworthy that the animal bone support can improve the activity for the photocatalyst, which would provide further impetus to alternate synthesis strategies for photocatalysts and make the photocatalysis process faster, less expensive, and more environmentally friendly.

Controllable synthesis of SnO2@carbon hollow sphere based on bi-functional metallo-organic molecule for high-performance anode in Li-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Haiyan; Li, Liuqing; Li, Zhaopeng; Zhong, Weihao; Liao, Haiyang; Li, Zhenghui

2018-06-01

Constructing hollow structure and nano-sized SnO2 particles are two normal strategies to improve lithium storage performance of SnO2-based electrode. But it is still challengeable to fabricate ultrasmall SnO2 embedded in carbon hollow sphere in a controllable way. Herein, we have synthesized a kind of SnO2@carbon hollow sphere via a confined Friedel-Crafts crosslinking of a novel metal-organic compound (triphenyltin chloride, named Sn-Ph) on the surface of SiO2 template. The as-prepared SnO2@carbon hollow sphere has 10 nm-sized SnO2 particles embedded in amorphous carbon wall. Furthermore, 100, 200 and 400 nm-sized SnO2@carbon hollow spheres can be obtained by regulating the size of SiO2 template. When they are applied in lithium-ion batteries, the carbon structure can act as barriers to protect SnO2 particles from pulverization, and hollow core stores electrolyte and very small SnO2 particles of 10 nm shorten the diffusion distance of lithium ions. Thus, SnO2@carbon hollow sphere presents superior electrochemical performance. The first discharge and charge capacities reach 1378.5 and 507.3 mAh g-1 respectively, and 100 cycles later, its capacity remains 501.2 mAh g-1, indicating a capacity retention of 98.8% (C100th/C2nd).

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

PubMed Central

Epifani, Mauro; Kaciulis, Saulius; Mezzi, Alessio; Altamura, Davide; Giannini, Cinzia; Díaz, Raül; Force, Carmen; Genç, Aziz; Arbiol, Jordi; Siciliano, Pietro; Comini, Elisabetta; Concina, Isabella

2017-01-01

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. PMID:28300185

Electronic structure and magnetic properties of Ni-doped SnO2 thin films

NASA Astrophysics Data System (ADS)

Sharma, Mayuri; Kumar, Shalendra; Alvi, P. A.

2018-05-01

This paper reports the electronic structure and magnetic properties of Ni-doped SnO2 thin film which were grown on Si (100) substrate by PLD (pulse laser deposition) technique under oxygen partial pressure (PO2). For getting electronic structure and magnetic behavior, the films were characterized using near edge X-ray absorption fine structure spectroscopy (NEXAFS) and DC magnetization measurements. The NEXAFS study at Ni L3,2 edge has been done to understand the local environment of Ni and Sn ions within SnO2 lattice. DC magnetization measurement shows that the saturation magnetization increases with the increase in substitution of Ni2+ ions in the system.

Facile, low temperature synthesis of SnO2/reduced graphene oxide nanocomposite as anode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Hou, Chau-Chung; Brahma, Sanjaya; Weng, Shao-Chieh; Chang, Chia-Chin; Huang, Jow-Lay

2017-08-01

We demonstrate a facile, single step, low temperature and energy efficient strategy for the synthesis of SnO2-reduced graphene oxide (RGO) nanocomposite where the crystallization of SnO2 nanoparticles and the reduction of graphene oxide takes place simultaneously by an in situ chemical reduction process. The electrochemical property of the SnO2-RGO composite prepared by using low concentrations of reducing agent shows better Li storage performance, good rate capability (378 mAh g-1 at 3200 mA g-1) and stable capacitance (522 mAh g-1 after 50 cycles). Increasing the reductant concentration lead to crystallization of high concentration of SnO2 nanoparticle aggregation and degrade the Li ion storage property.

Hydrothermal synthesis of nanostructured SnO particles through crystal growth in the presence of gelatin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uchiyama, Hiroaki, E-mail: h_uchi@kansai-u.ac.jp; Nakanishi, Shunsuke; Kozuka, Hiromitsu

2014-09-15

Crystalline SnO particles were obtained from Sn{sub 6}O{sub 4}(OH){sub 4} by the hydrothermal treatment in aqueous solutions containing gelatin at 150 °C for 24 h, where the morphologies of the SnO products changed from blocks to layered disks, stacked plates and unshaped aggregates with increasing amount of gelatin in the solutions. Such morphological changes of SnO particles were thought to be attributed to the suppression of the growth of SnO crystals by the adsorbed gelatin. - Graphical abstract: Nanostructured SnO particles were obtained from Sn{sub 6}O{sub 4}(OH){sub 4} by the hydrothermal treatment in gelatin solutions. - Highlights: • SnO particlesmore » were prepared from Sn{sub 6}O{sub 4}(OH){sub 4} by the hydrothermal treatment. • The adsorption of gelatin suppressed the growth of SnO crystals. • The shape of SnO particles depends on the amount of gelatin. • Blocks, disks, stacked plates and unshaped aggregates were obtained.« less

Control of box C/D snoRNP assembly by N6-methylation of adenine.

PubMed

Huang, Lin; Ashraf, Saira; Wang, Jia; Lilley, David Mj

2017-09-01

N 6 -methyladenine is the most widespread mRNA modification. A subset of human box C/D snoRNA species have target GAC sequences that lead to formation of N 6 -methyladenine at a key trans Hoogsteen-sugar A·G base pair, of which half are methylated in vivo The GAC target is conserved only in those that are methylated. Methylation prevents binding of the 15.5-kDa protein and the induced folding of the RNA Thus, the assembly of the box C/D snoRNP could in principle be regulated by RNA methylation at its critical first stage. Crystallography reveals that N 6 -methylation of adenine prevents the formation of trans Hoogsteen-sugar A·G base pairs, explaining why the box C/D RNA cannot adopt its kinked conformation. More generally, our data indicate that sheared A·G base pairs (but not Watson-Crick base pairs) are more susceptible to disruption by N 6 mA methylation and are therefore possible regulatory sites. The human signal recognition particle RNA and many related Alu retrotransposon RNA species are also methylated at N6 of an adenine that forms a sheared base pair with guanine and mediates a key tertiary interaction. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

Highly Sensitive H2S Sensor Based on the Metal-Catalyzed SnO2 Nanocolumns Fabricated by Glancing Angle Deposition

PubMed Central

Yoo, Kwang Soo; Han, Soo Deok; Moon, Hi Gyu; Yoon, Seok-Jin; Kang, Chong-Yun

2015-01-01

As highly sensitive H2S gas sensors, Au- and Ag-catalyzed SnO2 thin films with morphology-controlled nanostructures were fabricated by using e-beam evaporation in combination with the glancing angle deposition (GAD) technique. After annealing at 500 °C for 40 h, the sensors showed a polycrystalline phase with a porous, tilted columnar nanostructure. The gas sensitivities (S = Rgas/Rair) of Au and Ag-catalyzed SnO2 sensors fabricated by the GAD process were 0.009 and 0.015, respectively, under 5 ppm H2S at 300 °C, and the 90% response time was approximately 5 s. These sensors showed excellent sensitivities compared with the SnO2 thin film sensors that were deposited normally (glancing angle = 0°, S = 0.48). PMID:26134105

Roles of cobalt doping on ethanol-sensing mechanisms of flame-spray-made SnO2 nanoparticles-electrolytically exfoliated graphene interfaces

NASA Astrophysics Data System (ADS)

Punginsang, Matawee; Wisitsoraat, Anurat; Sriprachuabwong, Chakrit; Phokharatkul, Ditsayut; Tuantranont, Adisorn; Phanichphant, Sukon; Liewhiran, Chaikarn

2017-12-01

In this work, the roles of cobalt (Co) and electrolytically exfoliated graphene additives on ethanol gas-sensing properties of flame-spray-made SnO2 nanoparticles were systematically studied. Structural characterizations indicated that Co dopants formed solid solution with SnO2 nanoparticles while multilayer graphene sheets were well dispersed within the Co-doped SnO2 matrix at low graphene loading contents. The sensing films were fabricated by a spin coating process and tested towards 50-1000 ppm ethanol at 150-400 °C. It was found that the response to 1000 ppm ethanol at the optimal working temperature of 350 °C was enhanced from 91 to 292 and to 803 by 0.5 wt% graphene loading and 0.5 wt% Co-doping, respectively. The combination of Co-doping and graphene loading with the same concentration of 0.5 wt% led to a synergistic enhancement of ethanol response to 2147 at 1000 ppm with a short response time of ∼0.9 s and fast recovery stabilization at 350 °C, proving the significance of dopant on the gas-sensing performances of graphene/SnO2 composites. Furthermore, the optimal sensor exhibited high ethanol selectivity against C3H6O, NO2, H2S, H2, CH4 and humidity. The mechanisms for the ethanol response enhancement were proposed on the basis of combinative effects of catalytic substitutional p-type Co dopants and active graphene-Co-doped SnO2 M-S junctions with highly accessible surface area of micropores and mesopores in the composites. Therefore, the graphene loaded Co-doped SnO2 sensor is highly potential for responsive and selective detection of ethanol vapor at ppm levels and may be practically useful for drunken driving applications.

Synthesis and Behavior of Cetyltrimethyl Ammonium Bromide Stabilized Zn1+xSnO3+x (0 ≤ x ≤1) Nano-Crystallites

PubMed Central

Placke, Astrid; Kumar, Ashok; Priya, Shashank

2016-01-01

We report synthesis of cetyltrimethyl ammonium bromide (CTAB) stabilized Zn1+xSnO3+x (0 ≤ x ≤1) nano-crystallites by facile cost-effective wet chemistry route. The X-ray diffraction patterns of as-synthesized powders at the Zn/Sn ratio of 1 exhibited formation of ZnSn(OH)6. Increasing the Zn/Sn ratio further resulted in the precipitation of an additional phase corresponding to Zn(OH)2. The decomposition of these powders at 650°C for 3h led to the formation of the orthorhombic phase of ZnSnO3 and tetragonal SnO2-type phase of Zn2SnO4 at the Zn/Sn ratio of 1 and 2, respectively, with the formation of their mixed phases at intermediate compositions, i.e., at Zn/Sn ratio of 1.25, 1.50 and 1.75, respectively. The lattice parameters of orthorhombic and tetragonal phases were a ~ 3.6203 Å, b ~ 4.2646 Å and c ~ 12.8291Å (for ZnSnO3) and a = b ~ 5.0136 Å and c ~ 3.3055Å (for Zn2SnO4). The transmission electron micrographs revealed the formation of nano-crystallites with aspect ratio ~ 2; the length and thickness being 24, 13 nm (for ZnSnO3) and 47, 22 nm (for Zn2SnO4), respectively. The estimated direct bandgap values for the ZnSnO3 and Zn2SnO4 were found to be 4.21 eV and 4.12 eV, respectively. The ac conductivity values at room temperature (at 10 kHz) for the ZnSnO3 and Zn2SnO4 samples were 8.02 × 10−8 Ω-1 cm-1 and 6.77 × 10−8 Ω-1 cm-1, respectively. The relative permittivity was found to increase with increase in temperature, the room temperature values being 14.24 and 25.22 for the samples ZnSnO3 and Zn2SnO4, respectively. Both the samples, i.e., ZnSnO3 and Zn2SnO4, exhibited low values of loss tangent up to 300 K, the room temperature values being 0.89 and 0.72, respectively. A dye-sensitized solar cell has been fabricated using the optimized sample of zinc stannate photo-anode, i.e., Zn2SnO4. The cyclic voltammetry revealed oxidation and reduction around 0.40 V (current density ~ 11.1 mA/cm2) and 0.57 V (current density– 11.7 mA/cm2) for Zn2SnO4

The selective catalytic reduction of NO with NH3 over a novel Ce-Sn-Ti mixed oxides catalyst: Promotional effect of SnO2

NASA Astrophysics Data System (ADS)

Yu, Ming'e.; Li, Caiting; Zeng, Guangming; Zhou, Yang; Zhang, Xunan; Xie, Yin'e.

2015-07-01

A series of novel catalysts (CexSny) for the selective catalytic reduction of NO by NH3 were prepared by the inverse co-precipitation method. The aim of this novel design was to improve the NO removal efficiency of CeTi by the introduction of SnO2. It was found that the Ce-Sn-Ti catalyst was much more active than Ce-Ti and the best Ce:Sn molar ratio was 2:1. Ce2Sn1 possessed a satisfied NO removal efficiency at low temperature (160-280 °C), while over 90% NO removal efficiency maintained in the temperature range of 280-400 °C at the gas hourly space velocity (GHSV) of 50,000 h-1. Besides, Ce2Sn1 kept a stable NO removal efficiency within a wide range of GHSV and a long period of reacting time. Meanwhile, Ce2Sn1 exhibited remarkable resistance to both respectively and simultaneously H2O and SO2 poisoning due to the introduction of SnO2. The promotional effect of SnO2 was studied by N2 adsorption-desorption, X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS) and H2 temperature programmed reduction (H2-TPR) for detail information. The characterization results revealed that the excellent catalytic performance of Ce2Sn1 was associated with the higher specific surface area, larger pore volume and poorer crystallization. Besides, the introduction of SnO2 could result in not only greater conversion of Ce4+ to Ce3+ but also the increase amount of chemisorbed oxygen, which are beneficial to improve the SCR activity. More importantly, a novel peak appearing at lower temperatures through the new redox equilibrium of 2Ce4+ + Sn2+ ↔ 2Ce3+ + Sn4+ and higher total H2 consumption can be obtained by the addition of SnO2. Finally, the possible reaction mechanism of the selective catalytic reduction over Ce2Sn1 was also proposed.

Hierarchical ZnO Nanowires-loaded Sb-doped SnO2-ZnO Micrograting Pattern via Direct Imprinting-assisted Hydrothermal Growth and Its Selective Detection of Acetone Molecules.

PubMed

Choi, Hak-Jong; Choi, Seon-Jin; Choo, Soyoung; Kim, Il-Doo; Lee, Heon

2016-01-08

We propose a novel synthetic route by combining imprinting transfer of a Sb-doped SnO2 (ATO)-ZnO composite micrograting pattern (MP), i.e., microstrip lines, on a sensor substrate and subsequent hydrothermal growth of ZnO nanowires (NWs) for producing a hierarchical ZnO NW-loaded ATO-ZnO MP as an improved chemo-resistive sensing layer. Here, ATO-ZnO MP structure with 3-μm line width, 9-μm pitch, and 6-μm height was fabricated by direct transfer of mixed ATO and ZnO nanoparticle (NP)-dispersed resists, which are pre-patterned on a polydimethylsiloxane (PDMS) mold. ZnO NWs with an average diameter of less than 50 nm and a height of 250 nm were quasi-vertically grown on the ATO-ZnO MP, leading to markedly enhanced surface area and heterojunction composites between each ATO NP, ZnO NP, and ZnO NW. A ZnO NW-loaded MP sensor with a relative ratio of 1:9 between ATO and ZnO (1:9 ATO-ZnO), exhibited highly sensitive and selective acetone sensing performance with 2.84-fold higher response (R air/R gas = 12.8) compared to that (R air/R gas = 4.5) of pristine 1:9 ATO-ZnO MP sensor at 5 ppm. Our results demonstrate the processing advantages of direct imprinting-assisted hydrothermal growth for large-scale homogeneous coating of hierarchical oxide layers, particularly for applications in highly sensitive and selective chemical sensors.

Hierarchical ZnO Nanowires-loaded Sb-doped SnO2-ZnO Micrograting Pattern via Direct Imprinting-assisted Hydrothermal Growth and Its Selective Detection of Acetone Molecules

PubMed Central

Choi, Hak-Jong; Choi, Seon-Jin; Choo, Soyoung; Kim, Il-Doo; Lee, Heon

2016-01-01

We propose a novel synthetic route by combining imprinting transfer of a Sb-doped SnO2 (ATO)-ZnO composite micrograting pattern (MP), i.e., microstrip lines, on a sensor substrate and subsequent hydrothermal growth of ZnO nanowires (NWs) for producing a hierarchical ZnO NW-loaded ATO-ZnO MP as an improved chemo-resistive sensing layer. Here, ATO-ZnO MP structure with 3-μm line width, 9-μm pitch, and 6-μm height was fabricated by direct transfer of mixed ATO and ZnO nanoparticle (NP)-dispersed resists, which are pre-patterned on a polydimethylsiloxane (PDMS) mold. ZnO NWs with an average diameter of less than 50 nm and a height of 250 nm were quasi-vertically grown on the ATO-ZnO MP, leading to markedly enhanced surface area and heterojunction composites between each ATO NP, ZnO NP, and ZnO NW. A ZnO NW-loaded MP sensor with a relative ratio of 1:9 between ATO and ZnO (1:9 ATO-ZnO), exhibited highly sensitive and selective acetone sensing performance with 2.84-fold higher response (Rair/Rgas = 12.8) compared to that (Rair/Rgas = 4.5) of pristine 1:9 ATO-ZnO MP sensor at 5 ppm. Our results demonstrate the processing advantages of direct imprinting-assisted hydrothermal growth for large-scale homogeneous coating of hierarchical oxide layers, particularly for applications in highly sensitive and selective chemical sensors. PMID:26743814

Hierarchical ZnO Nanowires-loaded Sb-doped SnO2-ZnO Micrograting Pattern via Direct Imprinting-assisted Hydrothermal Growth and Its Selective Detection of Acetone Molecules

NASA Astrophysics Data System (ADS)

Choi, Hak-Jong; Choi, Seon-Jin; Choo, Soyoung; Kim, Il-Doo; Lee, Heon

2016-01-01

We propose a novel synthetic route by combining imprinting transfer of a Sb-doped SnO2 (ATO)-ZnO composite micrograting pattern (MP), i.e., microstrip lines, on a sensor substrate and subsequent hydrothermal growth of ZnO nanowires (NWs) for producing a hierarchical ZnO NW-loaded ATO-ZnO MP as an improved chemo-resistive sensing layer. Here, ATO-ZnO MP structure with 3-μm line width, 9-μm pitch, and 6-μm height was fabricated by direct transfer of mixed ATO and ZnO nanoparticle (NP)-dispersed resists, which are pre-patterned on a polydimethylsiloxane (PDMS) mold. ZnO NWs with an average diameter of less than 50 nm and a height of 250 nm were quasi-vertically grown on the ATO-ZnO MP, leading to markedly enhanced surface area and heterojunction composites between each ATO NP, ZnO NP, and ZnO NW. A ZnO NW-loaded MP sensor with a relative ratio of 1:9 between ATO and ZnO (1:9 ATO-ZnO), exhibited highly sensitive and selective acetone sensing performance with 2.84-fold higher response (Rair/Rgas = 12.8) compared to that (Rair/Rgas = 4.5) of pristine 1:9 ATO-ZnO MP sensor at 5 ppm. Our results demonstrate the processing advantages of direct imprinting-assisted hydrothermal growth for large-scale homogeneous coating of hierarchical oxide layers, particularly for applications in highly sensitive and selective chemical sensors.

Ultrathin SnO2 nanorods: template- and surfactant-free solution phase synthesis, growth mechanism, optical, gas-sensing, and surface adsorption properties.

PubMed

Xi, Guangcheng; Ye, Jinhua

2010-03-01

A novel template- and surfactant-free low temperature solution-phase method has been successfully developed for the controlled synthesis of ultrathin SnO(2) single-crystalline nanorods for the first time. The ultrathin SnO(2) single-crystalline nanorods are 2.0 +/- 0.5 nm in diameter, which is smaller than its exciton Bohr radius. The ultrathin SnO(2) nanorods show a high specific area (191.5 m(2) g(-1)). Such a thin SnO(2) single-crystalline nanorod is new in the family of SnO(2) nanostrucures and presents a strong quantum confinement effect. Its formation depends on the reaction temperature as well as on the concentration of the urea solution. A nonclassical crystallization process, Ostwald ripening process followed by an oriented attachment mechanism, is proposed based on the detailed observations from a time-dependent crystal evolution process. Importantly, such structured SnO(2) has shown a strong structure-induced enhancement of gas-sensing properties and has exhibited greatly enhanced gas-sensing property for the detection of ethanol than that of other structured SnO(2), such as the powders of nanobelts and microrods. Moreover, these ultrathin SnO(2) nanorods exhibit excellent ability to remove organic pollutant in wastewater by enormous surface adsorption. These properties are mainly attributed to its higher surface-to-volume ratio and ultrathin diameter. This work provides a novel low temperature, green, and inexpensive pathway to the synthesis of ultrathin nanorods, offering a new material form for sensors, solar cells, catalysts, water treatments, and other applications.

Sono- and photocatalytic activities of SnO2 nanoparticles for degradation of cationic and anionic dyes

NASA Astrophysics Data System (ADS)

Paramarta, Valentinus; Taufik, Ardiansyah; Munisa, Lusitra; Saleh, Rosari

2017-01-01

The current research work focuses on the catalytic activity of SnO2 nanoparticles (NPs) against degradation of both cationic dye (methylene blue) and anionic dye (Congo-red). SnO2 NPs were synthesized under the sol-gel method and were characterized by performing X-ray diffraction, Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) Brunauer-Emmet-Teller (BET) surface area analysis and UV-Vis spectroscopy. The results demonstrate that SnO2 NPs has well crystalline structure with the crystallite size of 44 nm. The degradation of dyes was studied under ambient temperature using ultrasonicator and UV light, respectively. The sono- and photocatalytic activities of SnO2 NPs on dyes were analyzed by measuring the change in absorbance of dyes under UV-spectrophotometer. The degradation of the organic dyes has been calculated by monitoring the degradation in the concentration of the dyes before and after irradiation of ultrasonic and light, respectively. The influence of other parameters such as catalyst dosage, pH and scavenger have also been investigated. The catalytic activity is enhanced in the presence of ultrasonic irradiation. The degradation of both dyes follows pseudo-first order kinetics. The reusability tests have also been done to ensure the stability of the used catalysts. A reasonable mechanism of sono- and photocatalysis with SnO2 NPs has been proposed by correlating the active radical species involved with the physical properties of the as-synthesized samples.

Understanding the SNO+ Detector

DOE PAGES

Kamdin, K.

2015-03-24

SNO+, a large liquid scintillator experiment, is the successor of the Sudbury Neutrino Observatory (SNO) experiment. The scintillator volume will be loaded with large quantities of 130Te, an isotope that undergoes double beta decay, in order to search for neutrinoless double beta decay. In addition to this search, SNO+ has a broad physics program due to its sensitivity to solar and supernova neutrinos, as well as reactor and geo anti-neutrinos. SNO+ can also place competitive limits on certain modes of invisible nucleon decay during its first phase. The detector is currently undergoing commissioning in preparation for its first phase, inmore » which the detector is filled with ultra pure water. This will be followed by a pure scintillator phase, and then a Tellurium-loaded scintillator phase to search for neutrinoless double beta decay. Here we present the work done to model detector aging, which was first observed during SNO. The aging was found to reduce the optical response of the detector. We also describe early results from electronics calibration of SNO+.« less

Aerosol assisted chemical vapour deposition of gas sensitive SnO2 and Au-functionalised SnO2 nanorods via a non-catalysed vapour solid (VS) mechanism

PubMed Central

Vallejos, Stella; Selina, Soultana; Annanouch, Fatima Ezahra; Gràcia, Isabel; Llobet, Eduard; Blackman, Chris

2016-01-01

Tin oxide nanorods (NRs) are vapour synthesised at relatively lower temperatures than previously reported and without the need for substrate pre-treatment, via a vapour-solid mechanism enabled using an aerosol-assisted chemical vapour deposition method. Results demonstrate that the growth of SnO2 NRs is promoted by a compression of the nucleation rate parallel to the substrate and a decrease of the energy barrier for growth perpendicular to the substrate, which are controlled via the deposition conditions. This method provides both single-step formation of the SnO2 NRs and their integration with silicon micromachined platforms, but also allows for in-situ functionalization of the NRs with gold nanoparticles via co-deposition with a gold precursor. The functional properties are demonstrated for gas sensing, with microsensors using functionalised NRs demonstrating enhanced sensing properties towards H2 compared to those based on non-functionalised NRs. PMID:27334232

Paternally inherited microdeletion at 15q11.2 confirms a significant role for the SNORD116 C/D box snoRNA cluster in Prader-Willi syndrome.

PubMed

Duker, Angela L; Ballif, Blake C; Bawle, Erawati V; Person, Richard E; Mahadevan, Sangeetha; Alliman, Sarah; Thompson, Regina; Traylor, Ryan; Bejjani, Bassem A; Shaffer, Lisa G; Rosenfeld, Jill A; Lamb, Allen N; Sahoo, Trilochan

2010-11-01

Prader-Willi syndrome (PWS) is a neurobehavioral disorder manifested by infantile hypotonia and feeding difficulties in infancy, followed by morbid obesity secondary to hyperphagia. It is caused by deficiency of paternally expressed transcript(s) within the human chromosome region 15q11.2. PWS patients harboring balanced chromosomal translocations with breakpoints within small nuclear ribonucleoprotein polypeptide N (SNRPN) have provided indirect evidence for a role for the imprinted C/D box containing small nucleolar RNA (snoRNA) genes encoded downstream of SNRPN. In addition, recently published data provide strong evidence in support of a role for the snoRNA SNORD116 cluster (HBII-85) in PWS etiology. In this study, we performed detailed phenotypic, cytogenetic, and molecular analyses including chromosome analysis, array comparative genomic hybridization (array CGH), expression studies, and single-nucleotide polymorphism (SNP) genotyping for parent-of-origin determination of the 15q11.2 microdeletion on an 11-year-old child expressing the major components of the PWS phenotype. This child had an ∼236.29 kb microdeletion at 15q11.2 within the larger Prader-Willi/Angelman syndrome critical region that included the SNORD116 cluster of snoRNAs. Analysis of SNP genotypes in proband and mother provided evidence in support of the deletion being on the paternal chromosome 15. This child also met most of the major PWS diagnostic criteria including infantile hypotonia, early-onset morbid obesity, and hypogonadism. Identification and characterization of this case provide unequivocal evidence for a critical role for the SNORD116 snoRNA molecules in PWS pathogenesis. Array CGH testing for genomic copy-number changes in cases with complex phenotypes is proving to be invaluable in detecting novel alterations and enabling better genotype-phenotype correlations.

Studying Structural, Optical, Electrical, and Sensing Properties of Nanocrystalline SnO2:Cu Films Prepared by Sol-Gel Method for CO Gas Sensor Application at Low Temperature

NASA Astrophysics Data System (ADS)

Al-Jawad, Selma M. H.; Elttayf, Abdulhussain K.; Saber, Amel S.

Nanocrystalline SnO2 and SnO2:Cu thin films derived from SnCl2ṡ2H2O precursors have been prepared on glass substrates using sol-gel dip-coating technique. The deposited film was 300±20nm thick and the films were annealed in air at 500∘C for 1h. Structural, optical and sensing properties of the films were studied under different preparation conditions, such as Cu-doping concentration of 2%, 4% and 6wt.%. X-ray diffraction studies show the polycrystalline nature with tetragonal rutile structure of SnO2 and Cu:SnO2 thin films. The films have highly preferred orientation along (110). The crystallite size of the prepared samples reduced with increasing Cu-doping concentrations and the addition of Cu as dopants changed the structural properties of the thin films. Surface morphology was determined through scanning electron microscopy and atomic force microscopy. Results show that the particle size decreased as doping concentration increased. The films have moderate optical transmission (up to 82.4% at 800nm), and the transmittance, absorption coefficient and energy gap at different Cu-doping concentration were measured and calculated. Results show that Cu-doping decreased the transmittance and energy gap whereas it increased the absorption coefficient. Two peaks were noted with Cu-doping concentration of 0-6wt.%; the first peak was positioned exactly at 320nm ultraviolet emission and the second was positioned at 430-480nm. Moreover, emission bands were noticed in the photoluminescence spectra of Cu:SnO2. The electrical properties of SnO2 films include DC electrical conductivity, showing that the films have two activation energies, namely, Ea1 and Ea2, which increase as Cu-doping concentration increases. Cudoped nanocrystalline SnO2 gas-sensing material has better sensitivity to CO gas compared with pure SnO2.

The effect of noble metal additives on the optimum operating temperature of SnO2 gas sensors

NASA Astrophysics Data System (ADS)

Mohammad-Yousefi, S.; Rahbarpour, S.; Ghafoorifard, H.

2017-12-01

The effect of Pd and Au additives on gas sensing properties of SnO2 was investigated. SnO2 pallets were fabricated and sintered at 900 °C for 90 minutes. Several nanometer layers of Pd and Au were deposited on separate SnO2 pallets and were intentionally dispersed into the SnO2 pallets by long heat treatment (400 °C for 1 Day). All metal loaded samples showed significant enhancement in response level and optimum operating temperature compare to pure SnO2 gas sensors. The amount of enhancement was strongly dependent on the material and the thickness of deposited metal layer. Studying butanol response showed that increasing the thickness of metal causes the response level to increase. Further thickness increase caused contrary effect and decreased the performance of sensors. Best results were achieved at 10 nm-thick Au and 7 nm-thick Pd. Generally, Pd-SnO2 samples demonstrated better performance than Au-SnO2 ones, however, Au-SnO2 samples were proved to be good candidate to sense reducing gases with lower hydrogen atoms in their formula. Given experimental results were also good evidence of chemical activity of gold and simply confirms the relation between chemical activity and gold particle size. Results were qualitatively described by gas diffusion theory and surface reactions take place on metal particles.The first section in your paper

Influence of particle size and water coverage on the thermodynamic properties of water confined on the surface of SnO2 cassiterite nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spencer, Elinor; Ross, Dr. Nancy; Parker, Stewart F.

2011-01-01

Inelastic neutron scattering (INS) data for SnO2 nanoparticles of three different sizes and varying hydration levels are presented. Data were recorded on five nanoparticle samples that had the following compositions: 2 nm SnO2*0.82H2O, 6 nm SnO2*0.055H2O, 6 nm SnO2*0.095H2O, 20 nm SnO2*0.072H2O, and 20 nm SnO2*0.092H2O. The isochoric heat capacity and vibrational entropy values at 298 K for the water confined on the surface of these nanoparticles were calculated from the vibrational density of states that were extracted from the INS data. This study has shown that the hydration level of the SnO2 nanoparticles influences the thermodynamic properties of themore » water layers and, most importantly, that there appears to be a critical size limit for SnO2 between 2 and 6 nm below which the particle size also affects these properties and above which it does not. These results have been compared with those for isostructural rutile-TiO2 nanoparticles [TiO2*0.22H2O and TiO2*0.37H2O], which indicated that water on the surface of TiO2 nanoparticles is more tightly bound and experiences a greater degree of restricted motion with respect to water on the surface of SnO2 nanoparticles. This is believed to be a consequence of the difference in chemical composition, and hence surface properties, of these metal oxide nanoparticles.« less

Resonant photoemission spectroscopic studies of SnO2 thin films

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Chauhan, R. S.; Panchal, Gyanendra; Singh, C. P.; Dar, Tanveer A.; Phase, D. M.; Choudhary, R. J.

2017-09-01

We report the structural and electronic properties of single phase, polycrystalline rutile tetragonal SnO2 thin film grown on Si (100) substrate by pulsed laser deposition technique. X-ray photoelectron and resonant photoemission spectroscopic (RPES) studies divulge that Sn is present in 4+ (˜91%) valence state with a very small involvement of 2+ (˜9%) valence state at the surface. Valence band spectrum of the film shows prominent contribution due to the Sn4+ valence state. RPES measurements were performed in the Sn 4d→5p photo absorption region. This study shows that O-2p, Sn-5s, and Sn-5p partial density of states are the main contributions to the valence band of this material. The resonance behavior of these three contributions has been analyzed. Constant initial state versus photon energy plots suggest that the low binding energy feature at ˜2.8 eV results from the hybridization of the O-2p and mixed valence states of Sn, while remaining features at higher binding energies are due to the hybridization between O-2p (bonding) orbitals and Sn4+ valence state.

Synthesis of SnO2 pillared carbon using long chain alkylamine grafted graphene oxide: an efficient anode material for lithium ion batteries

NASA Astrophysics Data System (ADS)

Reddy, M. Jeevan Kumar; Ryu, Sung Hun; Shanmugharaj, A. M.

2015-12-01

With the objective of developing new advanced composite materials that can be used as anodes for lithium ion batteries (LIBs), herein we describe the synthesis of SnO2 pillared carbon using various alkylamine (hexylamine; dodecylamine and octadecylamine) grafted graphene oxides and butyl trichlorotin precursors followed by its calcination at 500 °C for 2 h. While the grafted alkylamine induces crystalline growth of SnO2 pillars, thermal annealing of alkylamine grafted graphene oxide results in the formation of amorphous carbon coated graphene. Field emission scanning electron microscopy (FE-SEM) results reveal the successful formation of SnO2 pillared carbon on the graphene surface. X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy characterization corroborates the formation of rutile SnO2 crystals on the graphene surface. A significant rise in the BET surface area is observed for SnO2 pillared carbon, when compared to pristine GO. Electrochemical characterization studies of SnO2 pillared carbon based anode materials showed an enhanced lithium storage capacity and fine cyclic performance in comparison with pristine GO. The initial specific capacities of SnO2 pillared carbon are observed to be 1379 mA h g-1, 1255 mA h g-1 and 1360 mA h g-1 that decrease to 750 mA h g-1, 643 mA h g-1 and 560 mA h g-1 depending upon the chain length of grafted alkylamine on the graphene surface respectively. Electrochemical impedance spectral analysis reveals that the exchange current density of SnO2 pillared carbon based electrodes is higher, corroborating its enhanced electrochemical activity in comparison with GO based electrodes.With the objective of developing new advanced composite materials that can be used as anodes for lithium ion batteries (LIBs), herein we describe the synthesis of SnO2 pillared carbon using various alkylamine (hexylamine; dodecylamine and octadecylamine) grafted graphene oxides and butyl trichlorotin precursors

Synthesis of SnO2versus Sn crystals within N-doped porous carbon nanofibers via electrospinning towards high-performance lithium ion batteries

NASA Astrophysics Data System (ADS)

Wang, Hongkang; Lu, Xuan; Li, Longchao; Li, Beibei; Cao, Daxian; Wu, Qizhen; Li, Zhihui; Yang, Guang; Guo, Baolin; Niu, Chunming

2016-03-01

The design of tin-based anode materials (SnO2 or Sn) has become a major concern for lithium ion batteries (LIBs) owing to their different inherent characteristics. Herein, particulate SnO2 or Sn crystals coupled with porous N-doped carbon nanofibers (denoted as SnO2/PCNFs and Sn/PCNFs, respectively) are fabricated via the electrospinning method. The electrochemical behaviors of both SnO2/PCNFs and Sn/PCNFs are systematically investigated as anodes for LIBs. When coupled with porous carbon nanofibers, both SnO2 nanoparticles and Sn micro/nanoparticles display superior cycling and rate performances. SnO2/PCNFs and Sn/PCNFs deliver discharge capacities of 998 and 710 mA h g-1 after 140 cycles (at 100, 200, 500 and 1000 mA g-1 each for 10 cycles and then 100 cycles at 100 mA g-1), respectively. However, the Sn/PCNF electrodes show better cycling stability at higher current densities, delivering higher discharge capacities of 700 and 550 mA h g-1 than that of SnO2/PCNFs (685 and 424 mA h g-1) after 160 cycles at 200 and 500 mA g-1, respectively. The different superior electrochemical performance is attributed to the introduction of porous N-doped carbon nanofibers and their self-constructed networks, which, on the one hand, greatly decrease the charge-transfer resistance due to the high conductivity of N-doped carbon fibers; on the other hand, the porous carbon nanofibers with numerous voids and flexible one-dimensional (1D) structures efficiently alleviate the volume changes of SnO2 and Sn during the Li-Sn alloying-dealloying processes. Moreover, the discussion of the electrochemical behaviors of SnO2vs. Sn would provide new insights into the design of tin-based anode materials for practical applications, and the current strategy demonstrates great potential in the rational design of metallic tin-based anode materials.The design of tin-based anode materials (SnO2 or Sn) has become a major concern for lithium ion batteries (LIBs) owing to their different inherent

1D Cu(OH)2 nanorod/2D SnO2 nanosheets core/shell structured array: Covering with graphene layer leads to excellent performances on lithium-ion battery

NASA Astrophysics Data System (ADS)

Xia, Huicong; Zhang, Jianan; Chen, Zhimin; Xu, Qun

2018-05-01

A facile in-situ growth strategy is employ to achieving the two-dimensional SnO2 nanosheets/one-dimensional Cu(OH)2 nanorods nanoarchitecture on Cu foil current collector (SnO2/Cu(OH)2/Cu foil), follow by modification of a uniform layer of graphene (G). Confine with the graphene layer and unique one-dimensional/two-dimensional the nanoarchitecture, the remarkably enhance electrical conductivity and structural stability of G/SnO2/Cu(OH)2/Cu foil leads to a high reversible capacity of 1080.6 mAh g-1 at a current density of 200 mA g-1, much better than the samples without graphene (512.6 mAh g-1) and Cu(OH)2 nanorod (117.4 mAh g-1). Furthermore, G/SnO2/Cu(OH)2/Cu foil electrode shows high rate capacity (600.8 mAh g-1 at 1 A g-1) and excellent cycling stability (1057.1 mAh g-1 at 200 mA g-1 even after 500 cycles). This work highlights that increasing surface and interface effects with desirable three-dimensional nanoarchitecture can open a new avenue to electrochemical performance improvement in lithium-ion battery for SnO2-base anode.

Metal organic frameworks-derived sensing material of SnO2/NiO composites for detection of triethylamine

NASA Astrophysics Data System (ADS)

Bai, Shouli; Liu, Chengyao; Luo, Ruixian; Chen, Aifan

2018-04-01

The SnO2/NiO composites were synthesized by hydrothermal followed by calcination using metal-organic framework (MOF) consisting of the ligand of p-benzene-dicarboxylic acid (PTA) and the Sn and Ni center ions as sacrificial templates. The structure and morphology of Sn/Ni-based MOF and SnO2/NiO composites were characterized by XRD, SEM, TEM, FT-IR, TG, XPS and Brunauer-Emmett-Teller analysis. Sensing experiments reveal that the SnO2/NiO composite with the molar ratio of 9:1 not only exhibits the highest response of 14.03 that is 3 times higher than pristine SnO2 to triethylamine at 70 °C, but also shows good selectivity. Such excellent performance is attributed to the MOF-driven strategy and the formation of p-n heterojunctions, because the metal ions can be highly dispersed and separated in the MOFs and can prevent the metal ions aggregation during the MOF decomposition process. The work is a novel route for synthesis of gas sensing material.

Piper Ornatum and Piper Betle as Organic Dyes for TiO2 and SnO2 Dye Sensitized Solar Cells

NASA Astrophysics Data System (ADS)

Hayat, Azwar; Putra, A. Erwin E.; Amaliyah, Novriany; Hayase, Shuzi; Pandey, Shyam. S.

2018-03-01

Dye sensitized solar cell (DSSC) mimics the principle of natural photosynthesis are now currently investigated due to low manufacturing cost as compared to silicon based solar cells. In this report, we utilized Piper ornatum (PO) and Piper betle (PB) as sensitizer to fabricate low cost DSSCs. We compared the photovoltaic performance of both sensitizers with Titanium dioxide (TiO2) and Tin dioxide (SnO2) semiconductors. The results show that PO and PB dyes have higher Short circuit current (Jsc) when applied in SnO2 compared to standard TiO2 photo-anode film even though the Open circuit voltage (Voc) was hampered on SnO2 device. In conclusion, from the result, higher electron injections can be achieved by choosing appropriate semiconductors with band gap that match with dyes energy level as one of strategy for further low cost solar cell.

Enhanced thermoelectric property of oxygen deficient nickel doped SnO2 for high temperature application

NASA Astrophysics Data System (ADS)

Paulson, Anju; Sabeer, N. A. Muhammad; Pradyumnan, P. P.

2018-04-01

Motivated by the detailed investigation on the thermoelectric performance of oxide materials our work concentrated on the influence of acceptor dopants and defect density in the lattice plane for the enhancement of thermoelectric power. The series of Sn1‑x Nix O2 (0.01 ≤ x ≤ 0.05) compositions were prepared by solid state reaction mechanism and found that 3 atomic percentage Ni doped SnO2 can be considered as a good candidate due to its promising electrical and transport properties. Defect lattices were introduced in the sample and the deviation from oxygen stochiometry was ensured using photoluminescence measurement. High power factor was obtained for the 3 atomic percentage nickel doped SnO2 due to the effective number of charge carrier concentration and the depletion of oxygen rich layers. Defect centered and acceptor doped SnO2 lattice opens a new door for energy harvesting at higher temperatures.

A room temperature ethanol sensor made from p-type Sb-doped SnO2 nanowires.

PubMed

Wu, Jyh Ming

2010-06-11

A p-type ethanol sensor with a response time of approximately 8.3 s at room temperature was produced by SnO(2):Sb nanowires. The electrical properties of p-type SnO(2) nanowires are stable with a hole concentration of 1.544 x 10(17) cm(-3) and a field-effect mobility of 22 cm(2) V(-2) S(-1). X-ray photoelectron spectroscopy (XPS) and Hall measurement revealed that as-synthesized nanowires exhibit p-type behavior. A comprehensive investigation of the p-type sensing mechanism is reported.

Role of the heterojunctions in In2O3-composite SnO2 nanorod sensors and their remarkable gas-sensing performance for NOx at room temperature

NASA Astrophysics Data System (ADS)

Xu, Shuang; Gao, Jun; Wang, Linlin; Kan, Kan; Xie, Yu; Shen, Peikang; Li, Li; Shi, Keying

2015-08-01

Establishing heterostructures, as a good strategy to improve gas sensing performance, has been studied extensively. In this research, In2O3-composite SnO2 nanorod (ICTOs) heterostructures have been prepared via electrospinning, followed by calcination. It is found that In2O3 can improve the carrier density and oxygen deficiency of SnO2. In particular, the 3ICTO (Sn : In atom ratio of 25 : 0.3) nanorods with special particle distributions show an excellent sensing response towards different concentrations of NOx at room temperature. The highest sensing response is up to 8.98 for 100 ppm NOx with a fast response time of 4.67 s, which is over 11 times higher than that of pristine SnO2 nanorods at room temperature and the lowest detection limit is down to 0.1 ppm. More significantly, it presents good stability after 30 days for NOx of low concentration (0.1 ppm and 0.5 ppm). In addition, the rational band structure model combined with the surface depletion model which describe the NOx gas sensing mechanism of 3ICTO are presented. The 3ICTO nanorods may be promising in the application of gas sensors.Establishing heterostructures, as a good strategy to improve gas sensing performance, has been studied extensively. In this research, In2O3-composite SnO2 nanorod (ICTOs) heterostructures have been prepared via electrospinning, followed by calcination. It is found that In2O3 can improve the carrier density and oxygen deficiency of SnO2. In particular, the 3ICTO (Sn : In atom ratio of 25 : 0.3) nanorods with special particle distributions show an excellent sensing response towards different concentrations of NOx at room temperature. The highest sensing response is up to 8.98 for 100 ppm NOx with a fast response time of 4.67 s, which is over 11 times higher than that of pristine SnO2 nanorods at room temperature and the lowest detection limit is down to 0.1 ppm. More significantly, it presents good stability after 30 days for NOx of low concentration (0.1 ppm and 0.5 ppm). In

Preparation of p-type GaN-doped SnO2 thin films by e-beam evaporation and their applications in p-n junction

NASA Astrophysics Data System (ADS)

Lv, Shuliang; Zhou, Yawei; Xu, Wenwu; Mao, Wenfeng; Wang, Lingtao; Liu, Yong; He, Chunqing

2018-01-01

Various transparent GaN-doped SnO2 thin films were deposited on glass substrates by e-beam evaporation using GaN:SnO2 targets of different GaN weight ratios. It is interesting to find that carrier polarity of the thin films was converted from n-type to p-type with increasing GaN ratio higher than 15 wt.%. The n-p transition in GaN-doped SnO2 thin films was explained for the formation of GaSn and NO with increasing GaN doping level in the films, which was identified by Hall measurement and XPS analysis. A transparent thin film p-n junction was successfully fabricated by depositing p-type GaN:SnO2 thin film on SnO2 thin film, and a low leakage current (6.2 × 10-5 A at -4 V) and a low turn-on voltage of 1.69 V were obtained for the p-n junction.

Carbon-Confined SnO2-Electrodeposited Porous Carbon Nanofiber Composite as High-Capacity Sodium-Ion Battery Anode Material.

PubMed

Dirican, Mahmut; Lu, Yao; Ge, Yeqian; Yildiz, Ozkan; Zhang, Xiangwu

2015-08-26

Sodium resources are inexpensive and abundant, and hence, sodium-ion batteries are promising alternative to lithium-ion batteries. However, lower energy density and poor cycling stability of current sodium-ion batteries prevent their practical implementation for future smart power grid and stationary storage applications. Tin oxides (SnO2) can be potentially used as a high-capacity anode material for future sodium-ion batteries, and they have the advantages of high sodium storage capacity, high abundance, and low toxicity. However, SnO2-based anodes still cannot be used in practical sodium-ion batteries because they experience large volume changes during repetitive charge and discharge cycles. Such large volume changes lead to severe pulverization of the active material and loss of electrical contact between the SnO2 and carbon conductor, which in turn result in rapid capacity loss during cycling. Here, we introduce a new amorphous carbon-coated SnO2-electrodeposited porous carbon nanofiber (PCNF@SnO2@C) composite that not only has high sodium storage capability, but also maintains its structural integrity while ongoing repetitive cycles. Electrochemical results revealed that this SnO2-containing nanofiber composite anode had excellent electrochemical performance including high-capacity (374 mAh g(-1)), good capacity retention (82.7%), and large Coulombic efficiency (98.9% after 100th cycle).

Investigation of Hydrogen-Like Muonium States in Nb-Doped SnO2 Films

NASA Astrophysics Data System (ADS)

Rabis, Annett; Prokscha, Thomas; Fabbri, Emiliana; Salman, Zaher; Schmidt, Thomas; Suter, Andreas

Little is known about the characteristics of hydrogen states in thin films of SnO2 and Nb doped SnO2 (NTO) and its influence on the electrical properties in these materials, which are promising candidates for metal-oxide supports in polymer electrolyte fuel cells. Here, we used low-energy muon spin rotation/relaxation (LE-μSR) to study hydrogen-like muonium (Mu) states between 5 and 300 K in undoped and Nb doped SnO2 films with Nb doping levels of 0.1 and 2%, respectively. The films were prepared by reactive DC magnetron sputtering on undoped Si substrates. Film thicknesses varied between 75 and 200 nm, and muons were implanted close to the surface at a mean depth of 10 nm, in the center of the films, and in some cases close to the NTO/Si interface. Our results of transverse-field and longitudinal-field μSR show striking similarities to recent bulk μSR measurements on various zirconia systems [Vieira et al., Phys. Rev. B 94, 115207 (2016)]. This suggests that in the NTO systems the same Mu configurations exist which are the interstitial site with a deep, isotropic atomic Mu state, and, as the dominant fraction, the oxygen bound configuration with polaronic character.

Thin-walled SnO2 nanotubes functionalized with Pt and Au catalysts via the protein templating route and their selective detection of acetone and hydrogen sulfide molecules

NASA Astrophysics Data System (ADS)

Jang, Ji-Soo; Kim, Sang-Joon; Choi, Seon-Jin; Kim, Nam-Hoon; Hakim, Meggie; Rothschild, Avner; Kim, Il-Doo

2015-10-01

Bio-inspired Pt (~2 nm) and Au (~2.7 nm) catalysts encapsulated by a protein shell, i.e., Pt-apoferritin (Pt@AF) and Au-apoferriten (Au@AF), were synthesized via the hollow protein nanocage (apoferritin) templating route and directly functionalized on the interior and exterior walls of electrospun SnO2 nanotubes (NTs) during controlled single-nozzle electrospinning followed by high temperature calcination with heating rate control. Fast crystallization of the exterior shell and outward diffusion of the interior Sn precursors and crystallites result in the continued growth of a tubular wall, which is related to rapid heating driven Ostwald-ripening behavior. Very importantly, the Pt and Au nanoparticles (NPs) were immobilized onto thin-walled SnO2 NTs with a diameter of ~350 nm and a shell thickness of ~40 nm without any aggregation of catalysts due to high dispersibility, which originated from repulsive electrostatic (Coulombic) forces acting on the surface charged protein shells, leading to an enhanced catalytic effect and outstanding gas sensing properties. Pt-loaded SnO2 NTs exhibited superior acetone response (Rair/Rgas = 92 at 5 ppm) compared to pure SnO2 NFs (Rair/Rgas = 4.8 at 5 ppm) and SnO2 NTs (Rair/Rgas = 11 at 5 ppm) while Au-loaded SnO2 NTs showed a high response when exposed to hydrogen sulfide (Rair/Rgas = 34 at 5 ppm), offering selective gas detection with minimal cross-sensitivity against other interfering gases such as NH3, CO, NO, C6H5CH3, and C5H12. Our results provide a new insight into facile, cost-effective, and highly dispersible catalyst loading on the interior and exterior walls of hollow metal oxide NTs via simple electrospinning as a potential breath analyzer.Bio-inspired Pt (~2 nm) and Au (~2.7 nm) catalysts encapsulated by a protein shell, i.e., Pt-apoferritin (Pt@AF) and Au-apoferriten (Au@AF), were synthesized via the hollow protein nanocage (apoferritin) templating route and directly functionalized on the interior and exterior walls

Investigation on Synthesis, Stability, and Thermal Conductivity Properties of Water-Based SnO2/Reduced Graphene Oxide Nanofluids

PubMed Central

Yu, Xiaofen; Wu, Qibai; Zhang, Haiyan; Zeng, Guoxun; Li, Wenwu; Qian, Yannan; Li, Yang; Yang, Guoqiang; Chen, Muyu

2017-01-01

With the rapid development of industry, heat removal and management is a major concern for any technology. Heat transfer plays a critically important role in many sectors of engineering; nowadays utilizing nanofluids is one of the relatively optimized techniques to enhance heat transfer. In the present work, a facile low-temperature solvothermal method was employed to fabricate the SnO2/reduced graphene oxide (rGO) nanocomposite. X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscope (XPS), Raman spectroscopy, and transmission electron microscopy (TEM) have been performed to characterize the SnO2/rGO nanocomposite. Numerous ultrasmall SnO2 nanoparticles with average diameters of 3–5 nm were anchored on the surface of rGO, which contain partial hydrophilic functional groups. Water-based SnO2/rGO nanofluids were prepared with various weight concentrations by using an ultrasonic probe without adding any surfactants. The zeta potential was measured to investigate the stability of the as-prepared nanofluid which exhibited great dispersion stability after quiescence for 60 days. A thermal properties analyzer was employed to measure thermal conductivity of water-based SnO2/rGO nanofluids, and the results showed that the enhancement of thermal conductivity could reach up to 31% at 60 °C under the mass fraction of 0.1 wt %, compared to deionized water. PMID:29280972

Hydrothermal self-assembly of novel porous flower-like SnO2 architecture and its application in ethanol sensor

NASA Astrophysics Data System (ADS)

Jiang, X. H.; Ma, S. Y.; Sun, A. M.; Zhang, Z. M.; Jin, W. X.; Wang, T. T.; Li, W. Q.; Xu, X. L.; Luo, J.; Cheng, L.; Mao, Y. Z.; Zhang, M.

2015-11-01

Different morphologies of tin dioxide (SnO2) architectures were prepared by increasing reaction time (12, 18, 24 and 48 h) under a facile hydrothermal process and followed by calcination. The crystal structures and morphologies of the hierarchical architecture were characterized in detail by means of powder X-ray diffraction (XRD), energy dispersive X-ray detector (EDX), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that the porous flower-like SnO2 architecture was obtained by 24 h hydrotherm treatment. Most importantly, the sensors based on porous flower-like SnO2 architecture exhibited perfect sensing performance toward ethanol with excellent selectivity, high response and fast response-recovery capability compared with other SnO2 nanoflowers for the same ethanol concentration at 300 °C. The response value was about 208 and the response-recovery time was around 8 and 7 s for 500 ppm ethanol, respectively. The enhancement in gas sensing properties was attributed to the unique structures, including the flower-like structure and porous feature, which provided more gas active center and diffusion pathways. The results indicated that porous flower-like SnO2 architecture was a potential candidate for fabricating effective ethanol sensor. Furthermore, the possible growth mechanism and the ethanol sensing mechanism of the architecture were discussed, too.

Synthesis of SnO2 pillared carbon using long chain alkylamine grafted graphene oxide: an efficient anode material for lithium ion batteries.

PubMed

Reddy, M Jeevan Kumar; Ryu, Sung Hun; Shanmugharaj, A M

2016-01-07

With the objective of developing new advanced composite materials that can be used as anodes for lithium ion batteries (LIBs), herein we describe the synthesis of SnO2 pillared carbon using various alkylamine (hexylamine; dodecylamine and octadecylamine) grafted graphene oxides and butyl trichlorotin precursors followed by its calcination at 500 °C for 2 h. While the grafted alkylamine induces crystalline growth of SnO2 pillars, thermal annealing of alkylamine grafted graphene oxide results in the formation of amorphous carbon coated graphene. Field emission scanning electron microscopy (FE-SEM) results reveal the successful formation of SnO2 pillared carbon on the graphene surface. X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy characterization corroborates the formation of rutile SnO2 crystals on the graphene surface. A significant rise in the BET surface area is observed for SnO2 pillared carbon, when compared to pristine GO. Electrochemical characterization studies of SnO2 pillared carbon based anode materials showed an enhanced lithium storage capacity and fine cyclic performance in comparison with pristine GO. The initial specific capacities of SnO2 pillared carbon are observed to be 1379 mA h g(-1), 1255 mA h g(-1) and 1360 mA h g(-1) that decrease to 750 mA h g(-1), 643 mA h g(-1) and 560 mA h g(-1) depending upon the chain length of grafted alkylamine on the graphene surface respectively. Electrochemical impedance spectral analysis reveals that the exchange current density of SnO2 pillared carbon based electrodes is higher, corroborating its enhanced electrochemical activity in comparison with GO based electrodes.

Effets de l'interaction avec l'oxygène sur le comportement de couches semi-conductrices de ZnO, SnO{2} et CdSe

NASA Astrophysics Data System (ADS)

Ain-Souya, A.; Ghers, M.; Haddad, A.; Tebib, W.; Rehamnia, R.; Messsalhi, A.; Bounouala, M.; Djouama, M. C.

2005-05-01

Les propriétés superficielles des matériaux solides diffèrent de celles du volume. A la surface, des défauts de différentes natures peuvent être présents. Ils permettent à la surface d'être interactive avec le milieu ambiant. Les multiples interactions entre les états de surface et des éléments du milieu extérieur peuvent modifier les propriétés superficielles. Ce travail étudie la régénération de couches semi-conductrices après adsorption isotherme d'oxygène à différentes températures effectuées entre 20 ° C et 300 ° C. Les matériaux qui ont servi à l'étude sont des couches de ZnO, SnO{2} et CdSe. Celles de CdSe ont été obtenues par co-évaporation, sous vide, de cadmium et de sélénium. Les échantillons de ZnO et SnO{2} ont été élaborés par oxydation, à des températures respectives de 450 ° C et 200 ° , de Zn et Sn déposés par électrolyse et par évaporation sous vide. Les matériaux évaporés ont été déposés sur des plaquettes en verre, les autres ont été électrodéposés sur des substrats métalliques. Les variations des propriétés électriques des couches ont été suivies par mesure de leur résistance électrique superficielle R. Les courbes LogR = f (103 /T (K)), relevées sous vide à différentes températures, sont caractéristiques d'un comportement de semi-conducteur. Des essais d'adsorption d'O{2} à différentes températures montrent des variations considérables de R. En effet, la chimisorption forte d'un gaz par une surface semi-conductrice est telle que l'échange électronique entre adsorbant et adsorbat provoque la formation d'une zone de charge d'espace modifiant la conduction superficielle. Les résultats mettent en évidence des domaines de température de plus haute sensibilité à l'oxygène. Pour le CdSe, certaines désorptions isothermes ont été suffisantes pour une régénération totale des échantillons. Les couches de ZnO ont souvent nécessité des désorptions programm

snoSeeker: an advanced computational package for screening of guide and orphan snoRNA genes in the human genome.

PubMed

Yang, Jian-Hua; Zhang, Xiao-Chen; Huang, Zhan-Peng; Zhou, Hui; Huang, Mian-Bo; Zhang, Shu; Chen, Yue-Qin; Qu, Liang-Hu

2006-01-01

Small nucleolar RNAs (snoRNAs) represent an abundant group of non-coding RNAs in eukaryotes. They can be divided into guide and orphan snoRNAs according to the presence or absence of antisense sequence to rRNAs or snRNAs. Current snoRNA-searching programs, which are essentially based on sequence complementarity to rRNAs or snRNAs, exist only for the screening of guide snoRNAs. In this study, we have developed an advanced computational package, snoSeeker, which includes CDseeker and ACAseeker programs, for the highly efficient and specific screening of both guide and orphan snoRNA genes in mammalian genomes. By using these programs, we have systematically scanned four human-mammal whole-genome alignment (WGA) sequences and identified 54 novel candidates including 26 orphan candidates as well as 266 known snoRNA genes. Eighteen novel snoRNAs were further experimentally confirmed with four snoRNAs exhibiting a tissue-specific or restricted expression pattern. The results of this study provide the most comprehensive listing of two families of snoRNA genes in the human genome till date.

Hollow SnO2 nanospheres with oxygen vacancies entrapped by a N-doped graphene network as robust anode materials for lithium-ion batteries.

PubMed

Wu, Naiteng; Du, Wuzhou; Gao, Xu; Zhao, Liang; Liu, Guilong; Liu, Xianming; Wu, Hao; He, Yan-Bing

2018-06-21

The practical application of tin dioxide (SnO2) in lithium-ion batteries has been greatly hindered by its large volumetric expansion and low conductivity. Thus, a rational design of the size, geometry and the pore structure of SnO2-based nanomaterials is still a dire demand. To this end, herein we report an effective approach for engineering hollow-structured SnO2 nanospheres with adequate surface oxygen vacancies simultaneously wrapped by a nitrogen-doped graphene network (SnO2-x/N-rGO) through an electrostatic adsorption-induced self-assembly together with a thermal reduction process. The close electrostatic attraction achieved a tight and uniform combination of positively charged SnO2 nanospheres with negatively charged graphene oxide (GO), which can alleviate the aggregation and volume expansion of the entrapped SnO2 nanospheres. Subsequent thermal treatment not only ensures a significant reduction of the GO sheets accompanying nitrogen-doping, but also induces the generation of oxygen vacancies on the surface of the SnO2 hollow nanospheres, together building up a long-range and bicontinuous transfer channel for rapid electron and ion transport. Because of these structural merits, the as-built SnO2-x/N-rGO composite used as the anode material exhibits excellent robust cycling stability (∼912 mA h g-1 after 500 cycles at 0.5 A g-1 and 652 mA h g-1 after 200 cycles at 1 A g-1) and superior rate capability (309 mA h g-1 at 10 A g-1). This facile fabrication strategy may pave the way for the construction of high performance SnO2-based anode materials for potential application in advanced lithium-ion batteries.

SnoN co-repressor binds and represses smad7 gene promoter.

PubMed

Briones-Orta, Marco A; Sosa-Garrocho, Marcela; Moreno-Alvarez, Paola; Fonseca-Sánchez, Miguel A; Macías-Silva, Marina

2006-03-17

SnoN and Ski oncoproteins are co-repressors for Smad proteins and repress TGF-beta-responsive gene expression. The smad7 gene is a TGF-beta target induced by Smad signaling, and its promoter contains the Smad-binding element (SBE) required for a positive regulation by the TGF-beta/Smad pathway. SnoN and Ski co-repressors also bind SBE but regulate negatively smad7 gene. Ski along with Smad4 binds and represses the smad7 promoter, whereas the repression mechanism by SnoN is not clear. Ski and SnoN overexpression inhibits smad7 reporter expression induced through TGF-beta signaling. Using chromatin immunoprecipitation assays, we found that SnoN binds smad7 promoter at the basal condition, whereas after a short TGF-beta treatment for 15-30 min SnoN is downregulated and no longer bound smad7 promoter. Interestingly, after a prolonged TGF-beta treatment SnoN is upregulated and returns to its position on the smad7 promoter, functioning probably as a negative feedback control. Thus, SnoN also seems to regulate negatively the TGF-beta-responsive smad7 gene by binding and repressing its promoter in a similar way to Ski.

Synthesis and characterization of binary ZnO-SnO2 (ZTO) thin films by e-beam evaporation technique

NASA Astrophysics Data System (ADS)

Bibi, Shagufta; Shah, A.; Mahmood, Arshad; Ali, Zahid; Raza, Qaisar; Aziz, Uzma; Haneef; Waheed, Abdul; Shah, Ziaullah

2018-04-01

The binary ZnO-SnO2 (ZTO) thin films with varying SnO2 concentrations (5, 10, 15, and 20 wt%) were grown on glass substrate by e-beam evaporation technique. The prepared ZTO films were annealed at 400 °C in air. These films were then characterized to investigate their structural, optical, and electrical properties as a function of SnO2 concentration. XRD analysis reveals that the crystallinity of the film decreases with the addition of SnO2 and it transforms to an amorphous structure at a composition of 40% SnO2 and 60% ZnO. Morphology of the films was examined by atomic force microscopy which points out that surface roughness of the films decreases with the increasing of SnO2 in the film. Optical properties such as optical transparency, band-gap energy, and optical constants of these films were examined by spectrophotometer and spectroscopic Ellipsometer. It was observed that the average optical transmission of mixed films improves with incorporation of SnO2. In addition, the band-gap energy of the films was determined to be in the range of 3.37-3.7 eV. Furthermore, it was found that the optical constants (n and k) decrease with the addition of SnO2. Similarly, it is observed that the electrical resistivity increases nonlinearly with the increase in SnO2 in ZnO-SnO2 thin films. However, it is noteworthy that the highest figure of merit (FOM) value, i.e., 55.87 × 10-5 Ω-1, is obtained for ZnO-SnO2 (ZTO) thin film with 40 wt% of SnO2 composition. Here, we suggest that ZnO-SnO2 (ZTO) thin film with composition of 60:40 wt% can be used as an efficient TCO film due to the improved transmission, and reduced RMS value and highest FOM value.

Sandwich-like MoS2 @SnO2 @C with High Capacity and Stability for Sodium/Potassium Ion Batteries.

PubMed

Chen, Zhi; Yin, Dangui; Zhang, Ming

2018-04-01

Sandwich-like MoS 2 @SnO 2 @C nanosheets are prepared by facile hydrothermal reactions. SnO 2 nanosheets can attach to exfoliated MoS 2 nanosheets to prevent restacking of adjacent MoS 2 nanosheets, and carbon transformed from polyvinylpyrrolidone is coated on MoS 2 @SnO 2 , forming a sandwich structure to maintain cycling stability. As an anode for sodium-ion batteries, the electrode greatly deliverers a high initial discharge specific capacity of 530 mA h g -1 and maintains at 396 mA h g -1 after 150 cycles at 0.1 A g -1 . Even at a large current density of 1 A g -1 , it can hold 230 mA h g -1 after 450 cycles. Besides, as an anode for K + storage, the electrode also shows a discharge capacity of 312 mA h g -1 after 25 cycles at 0.05 A g -1 . This work may provide a new strategy to prepare other composites which can be applied to new kind of rechargeable batteries. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Silicon surface passivation by PEDOT: PSS functionalized by SnO2 and TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

García-Tecedor, M.; Karazhanov, S. Zh; Vásquez, G. C.; Haug, H.; Maestre, D.; Cremades, A.; Taeño, M.; Ramírez-Castellanos, J.; González-Calbet, J. M.; Piqueras, J.; You, C. C.; Marstein, E. S.

2018-01-01

In this paper, we present a study of silicon surface passivation based on the use of spin-coated hybrid composite layers. We investigate both undoped poly(3,4-ethylenedioxythiophene)/poly-(styrenesulfonate) (PEDOT:PSS), as well as PEDOT:PSS functionalized with semiconducting oxide nanomaterials (TiO2 and SnO2). The hybrid compound was deposited at room temperature by spin coating—a potentially lower cost, lower processing time and higher throughput alternative compared with the commonly used vacuum-based techniques. Photoluminescence imaging was used to characterize the electronic properties of the Si/PEDOT:PSS interface. Good surface passivation was achieved by PEDOT:PSS functionalized by semiconducting oxides. We show that control of the concentration of semiconducting oxide nanoparticles in the polymer is crucial in determining the passivation performance. A charge carrier lifetime of about 275 μs has been achieved when using SnO2 nanoparticles at a concentration of 0.5 wt.% as a filler in the composite film. X-ray diffraction (XRD), scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive x-ray in an SEM, and μ-Raman spectroscopy have been used for the morphological, chemical and structural characterization. Finally, a simple model of a photovoltaic device based on PEDOT:PSS functionalized with semiconducting oxide nanoparticles has been fabricated and electrically characterized.

Silicon surface passivation by PEDOT: PSS functionalized by SnO2 and TiO2 nanoparticles.

PubMed

García-Tecedor, M; Karazhanov, S Zh; Vásquez, G C; Haug, H; Maestre, D; Cremades, A; Taeño, M; Ramírez-Castellanos, J; González-Calbet, J M; Piqueras, J; You, C C; Marstein, E S

2018-01-19

In this paper, we present a study of silicon surface passivation based on the use of spin-coated hybrid composite layers. We investigate both undoped poly(3,4-ethylenedioxythiophene)/poly-(styrenesulfonate) (PEDOT:PSS), as well as PEDOT:PSS functionalized with semiconducting oxide nanomaterials (TiO 2 and SnO 2 ). The hybrid compound was deposited at room temperature by spin coating-a potentially lower cost, lower processing time and higher throughput alternative compared with the commonly used vacuum-based techniques. Photoluminescence imaging was used to characterize the electronic properties of the Si/PEDOT:PSS interface. Good surface passivation was achieved by PEDOT:PSS functionalized by semiconducting oxides. We show that control of the concentration of semiconducting oxide nanoparticles in the polymer is crucial in determining the passivation performance. A charge carrier lifetime of about 275 μs has been achieved when using SnO 2 nanoparticles at a concentration of 0.5 wt.% as a filler in the composite film. X-ray diffraction (XRD), scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive x-ray in an SEM, and μ-Raman spectroscopy have been used for the morphological, chemical and structural characterization. Finally, a simple model of a photovoltaic device based on PEDOT:PSS functionalized with semiconducting oxide nanoparticles has been fabricated and electrically characterized.

MgO Nanoparticle Modified Anode for Highly Efficient SnO2-Based Planar Perovskite Solar Cells.

PubMed

Ma, Junjie; Yang, Guang; Qin, Minchao; Zheng, Xiaolu; Lei, Hongwei; Chen, Cong; Chen, Zhiliang; Guo, Yaxiong; Han, Hongwei; Zhao, Xingzhong; Fang, Guojia

2017-09-01

Reducing the energy loss and retarding the carrier recombination at the interface are crucial to improve the performance of the perovskite solar cell (PSCs). However, little is known about the recombination mechanism at the interface of anode and SnO 2 electron transfer layer (ETL). In this work, an ultrathin wide bandgap dielectric MgO nanolayer is incorporated between SnO 2 :F (FTO) electrode and SnO 2 ETL of planar PSCs, realizing enhanced electron transporting and hole blocking properties. With the use of this electrode modifier, a power conversion efficiency of 18.23% is demonstrated, an 11% increment compared with that without MgO modifier. These improvements are attributed to the better properties of MgO-modified FTO/SnO 2 as compared to FTO/SnO 2 , such as smoother surface, less FTO surface defects due to MgO passivation, and suppressed electron-hole recombinations. Also, MgO nanolayer with lower valance band minimum level played a better role in hole blocking. When FTO is replaced with Sn-doped In 2 O 3 (ITO), a higher power conversion efficiency of 18.82% is demonstrated. As a result, the device with the MgO hole-blocking layer exhibits a remarkable improvement of all J-V parameters. This work presents a new direction to improve the performance of the PSCs based on SnO 2 ETL by transparent conductive electrode surface modification.

The transforming activity of Ski and SnoN is dependent on their ability to repress the activity of Smad proteins.

PubMed

He, Jun; Tegen, Sarah B; Krawitz, Ariel R; Martin, G Steven; Luo, Kunxin

2003-08-15

The regulation of cell growth and differentiation by transforming growth factor-beta (TGF-beta) is mediated by the Smad proteins. In the nucleus, the Smad proteins are negatively regulated by two closely related nuclear proto-oncoproteins, Ski and SnoN. When overexpressed, Ski and SnoN induce oncogenic transformation of chicken embryo fibroblasts. However, the mechanism of transformation by Ski and SnoN has not been defined. We have previously reported that Ski and SnoN interact directly with Smad2, Smad3, and Smad4 and repress their ability to activate TGF-beta target genes through multiple mechanisms. Because Smad proteins are tumor suppressors, we hypothesized that the ability of Ski and SnoN to inactivate Smad function may be responsible for their transforming activity. Here, we show that the receptor regulated Smad proteins (Smad2 and Smad3) and common mediator Smad (Smad4) bind to different regions in Ski and SnoN. Mutation of both regions, but not each region alone, markedly impaired the ability of Ski and SnoN to repress TGF-beta-induced transcriptional activation and cell cycle arrest. Moreover, when expressed in chicken embryo fibroblasts, mutant Ski or SnoN defective in binding to the Smad proteins failed to induce oncogenic transformation. These results suggest that the ability of Ski and SnoN to repress the growth inhibitory function of the Smad proteins is required for their transforming activity. This may account for the resistance to TGF-beta-induced growth arrest in some human cancer cell lines that express high levels of Ski or SnoN.

Tetramethylene glycol mediated hydrothermal synthesis of defect-rich SnO2 nanoparticles for fast adsorption and degradation of MB dye

NASA Astrophysics Data System (ADS)

Rani, Barkha; Jadhao, Charushila Vasant; Sahu, Niroj Kumar

2018-04-01

Defect-rich pristine tin oxide nanoparticles (SnO2 NPs) with high colloidal stability have been synthesized by tetramethylene glycol (TMG) mediated hydrothermal process and characterized by XRD, TEM, Zeta Potential, PL spectroscopy and porosity measurement techniques. XRD result suggests the formation of rutile phase of SnO2 with average crystallite size of 2.65 nm. TMG act as a structure directing agent assist in the formation of network like structure of SnO2 NPs as confirmed from TEM. Significant blue shifts in the UV absorption spectrum as that of the bulk and defect bands in the PL spectrum are observed. The nanomaterial possesses very high surface area of 263.102 m2/g and large pore volume. The above properties strongly influence the photocatalytic degradation of methylene blue dye. Very fast adsorption and 96% degradation (under UV irradiation) has been achieved when 10 ppm methylene blue solutions is catalysed by 20 mg SnO2 NPs which pave the way for potential environmental application.

Ferromagnetism in two-dimensional hole-doped SnO

NASA Astrophysics Data System (ADS)

Houssa, M.; Iordanidou, K.; Pourtois, G.; Afanas'ev, V. V.; Stesmans, A.

2018-05-01

Hole-doped monolayer SnO has been recently predicted to be a ferromagnetic material, for a hole density typically above 5x1013/cm2. The possibility to induce a hole-doped stable ferromagnetic order in this two-dimensional material, either by intrinsic or extrinsic defects, is theoretically studied, using first-principles simulations. Sn vacancies and Sn vacancy-hydrogen complexes are predicted to be shallow acceptors, with relatively low formation energies in SnO monolayers grown under O-rich conditions. These defects produce spin-polarized gap states near the valence band-edge, potentially stabilizing the ferromagnetic order in 2D SnO. Hole-doping resulting from substitutional doping is also investigated. Among the considered possible dopants, As, substituting O, is predicted to produce shallow spin-polarized gap states near the valence band edge, also potentially resulting in a stable ferromagnetic order in SnO monolayers.

Promotion effect of Pt on a SnO2-WO3 material for NOx sensing

NASA Astrophysics Data System (ADS)

Wang, Chen-Yang; Hong, Zih-Siou; Wu, Ren-Jang

2015-05-01

Metal-oxide nanocomposites were prepared over screen-printed gold electrodes to be used as room-temperature NOx (nitric-oxide (NO) and nitrogen dioxide (NO2)) sensors. Various weight ratios of SnO2-WO3 and Pt loadings were used for NO sensing. The sensing materials were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface analysis. The NO-sensing results indicated that SnO2-WO3 (1:2) was more effective than other materials were. The sensor response (S=resistance of N2/resistance of NO=RN2/RNO) for detecting 1000 ppm of NO at room temperature was 2.6. The response time (T90) and recovery time (TR90) was 40 s and 86 s, respectively. By further loading with 0.5% Pt, the sensor response increased to 3.3. The response and recovery times of 0.5% Pt/SnO2-WO3 (1:2) were 40 s and 206 s, respectively. The linearity of the sensor response for a NO concentration range of 10-1000 ppm was 0.9729. A mechanism involving Pt promotion of the SnO2-WO3 heterojunction was proposed for NO adsorption, surface reaction, and adsorbed NO2 desorption.

High-performing visible-blind photodetectors based on SnO2/CuO nanoheterojunctions

PubMed Central

Xie, Ting; Hasan, Md Rezaul; Qiu, Botong; Arinze, Ebuka S.; Nguyen, Nhan V.; Motayed, Abhishek; Thon, Susanna M.; Debnath, Ratan

2017-01-01

We report on the significant performance enhancement of SnO2 thin film ultraviolet (UV) photodetectors (PDs) through incorporation of CuO/SnO2 p-n nanoscale heterojunctions. The nanoheterojunctions are self-assembled by sputtering Cu clusters that oxidize in ambient to form CuO. We attribute the performance improvements to enhanced UV absorption, demonstrated both experimentally and using optical simulations, and electron transfer facilitated by the nanoheterojunctions. The peak responsivity of the PDs at a bias of 0.2 V improved from 1.9 A/W in a SnO2-only device to 10.3 A/W after CuO deposition. The wavelength-dependent photocurrent-to-dark current ratio was estimated to be ~ 592 for the CuO/SnO2 PD at 290 nm. The morphology, distribution of nanoparticles, and optical properties of the CuO/SnO2 heterostructured thin films are also investigated. PMID:28729741

The Effect of Eu Doping on Microstructure, Morphology and Methanal-Sensing Performance of Highly Ordered SnO2 Nanorods Array

PubMed Central

Zhao, Yanping; Li, Yuehua; Ren, Xingping; Gao, Fan; Zhao, Heyun

2017-01-01

Layered Eu-doped SnO2 ordered nanoarrays constructed by nanorods with 10 nm diameters and several hundred nanometers length were synthesized by a substrate-free hydrothermal route using alcohol and water mixed solvent of sodium stannate and sodium hydroxide at 200 °C. The Eu dopant acted as a crystal growth inhibitor to prevent the SnO2 nanorods growth up, resulting in tenuous SnO2 nanorods ordered arrays. The X-ray diffraction (XRD) revealed the tetragonal rutile-type structure with a systematic average size reduction and unit cell volume tumescence, while enhancing the residual strain as the Eu-doped content increases. The surface defects that were caused by the incorporation of Eu ions within the surface oxide matrix were observed by high-resolution transmission electron microscope (HRTEM). The results of the response properties of sensors based on the different levels of Eu-doped SnO2 layered nanoarrays demonstrated that the 0.5 at % Eu-doped SnO2 layered nanorods arrays exhibited an excellent sensing response to methanal at 278 °C. The reasons of the enhanced sensing performance were discussed from the complicated defect surface structure, the large specific surface area, and the excellent catalytic properties of Eu dopant. PMID:29168796

Controlling the Sn-C bonds content in SnO2@CNTs composite to form in situ pulverized structure for enhanced electrochemical kinetics.

PubMed

Cheng, Yayi; Huang, Jianfeng; Qi, Hui; Cao, Liyun; Luo, Xiaomin; Li, Jiayin; Xu, Zhanwei; Yang, Jun

2017-12-07

The Sn-C bonding content between the SnO 2 and CNTs interface was controlled by the hydrothermal method and subsequent heat treatment. Electrochemical analysis found that the SnO 2 @CNTs with high Sn-C bonding content exhibited much higher capacity contribution from alloying and conversion reaction compared with the low content of Sn-C bonding even after 200 cycles. The high Sn-C bonding content enabled the SnO 2 nanoparticles to stabilize on the CNTs surface, realizing an in situ pulverization process of SnO 2 . The in situ pulverized structure was beneficial to maintain the close electrochemical contact of the working electrode during the long-term cycling and provide ultrafast transfer paths for lithium ions and electrons, which promoted the alloying and conversion reaction kinetics greatly. Therefore, the SnO 2 @CNTs composite with high Sn-C bonding content displayed highly reversible alloying and conversion reaction. It is believed that the composite could be used as a reference for design chemically bonded metal oxide/carbon composite anode materials in lithium-ion batteries.

Nanocrystalline SnO2 formation by oxygen ion implantation in tin thin films

NASA Astrophysics Data System (ADS)

Kondkar, Vidya; Rukade, Deepti; Kanjilal, Dinakar; Bhattacharyya, Varsha

2018-03-01

Metallic tin thin films of thickness 100 nm are deposited on fused silica substrates by thermal evaporation technique. These films are implanted with 45 keV oxygen ions at fluences ranging from 5 × 1015 to 5 × 1016 ions cm-2. The energy of the oxygen ions is calculated using SRIM in order to form embedded phases at the film-substrate interface. Post-implantation, films are annealed using a tube furnace for nanocrystalline tin oxide formation. These films are characterized using x-ray diffraction, Raman spectroscopy, UV-vis spectroscopy and photoluminescence spectroscopy. XRD and Raman spectroscopy studies reveal the formation of single rutile phase of SnO2. The size of the nanocrystallites formed decreases with an increase in the ion fluence. The nanocrystalline SnO2 formation is also confirmed by UV-vis and photoluminescence spectroscopy.

Overexpression of SnoN/SkiL, amplified at the 3q26.2 locus, in ovarian cancers: A role in ovarian pathogenesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nanjundan, Meera; Cheng, Kwai Wa; Zhang, Fan

2008-07-18

High-resolution array comparative genomic hybridization of 235 serous epithelial ovarian cancers demonstrated a regional increase at 3q26.2 encompassing SnoN/SkiL, a coregulator of SMAD/TGF{beta} signaling. SnoN RNA transcripts were elevated in {approx}80% of advanced stage serous epithelial ovarian cancers. In both immortalized normal (TIOSE) and ovarian carcinoma cell lines (OVCA), SnoN RNA levels were increased by TGF{beta} stimulation and altered by LY294002 and JNK II inhibitor treatment suggesting that the PI3K and JNK signaling pathways may regulate TGF{beta}-induced increases in SnoN RNA. In TIOSE, SnoN protein levels were reduced 15min post TGF{beta}-stimulation, likely by proteosome-mediated degradation. In contrast, in OVCA, SnoNmore » levels were elevated 3h post-stimulation potentially as a result of inhibition of the proteosome. To elucidate the role of SnoN in ovarian tumorigenesis, we explored the effects of both increasing and decreasing SnoN levels. In both TIOSE and OVCA, SnoN siRNA decreased cell growth between 20 and 50% concurrent with increased p21 levels. In TIOSE, transient expression of SnoN repressed TGF{beta} induction of PAI-1 promoters with little effect on the p21 promoter or resultant cell growth. In contrast to the effects of transient expression, stable expression of SnoN in TIOSE led to growth arrest through induction of senescence. Collectively, these results implicate SnoN levels in multiple roles during ovarian carcinogenesis: promoting cellular proliferation in ovarian cancer cells and as a positive mediator of cell cycle arrest and senescence in non-transformed ovarian epithelial cells.« less

Twin Crystal Induced near Zero Thermal Expansion in SnO2 Nanowires.

PubMed

Zhu, He; Li, Qiang; Yang, Chao; Zhang, Qinghua; Ren, Yang; Gao, Qilong; Wang, Na; Lin, Kun; Deng, Jinxia; Chen, Jun; Gu, Lin; Hong, Jiawang; Xing, Xianran

2018-06-20

Knowledge of controllable thermal expansion is a fundamental issue in the field of materials science and engineering. Direct blocking of the thermal expansions in positive thermal expansion materials is a challenging but fascinating task. Here we report a near zero thermal expansion (ZTE) of SnO 2 achieved from twin crystal nanowires, which is highly correlated to the twin boundaries. Local structural evolutions followed by pair distribution function revealed a remarkable thermal local distortion along the twin boundary. Lattice dynamics investigated by Raman scattering evidenced the hardening of phonon frequency induced by the twin crystal compressing, giving rise to the ZTE of SnO 2 nanowires. Further DFT calculation of Grüneisen parameters confirms the key role of compressive stress on ZTE. Our results provide an insight into the thermal expansion behavior regarding to twin crystal boundaries, which could be beneficial to the applications.

Effect of inhomogeneous Schottky barrier height of SnO2 nanowires device

NASA Astrophysics Data System (ADS)

Amorim, Cleber A.; Bernardo, Eric P.; Leite, Edson R.; Chiquito, Adenilson J.

2018-05-01

The current–voltage (I–V) characteristics of metal–semiconductor junction (Au–Ni/SnO2/Au–Ni) Schottky barrier in SnO2 nanowires were investigated over a wide temperature range. By using the Schottky–Mott model, the zero bias barrier height Φ B was estimated from I–V characteristics, and it was found to increase with increasing temperature; on the other hand the ideality factor (n) was found to decrease with increasing temperature. The variation in the Schottky barrier and n was attributed to the spatial inhomogeneity of the Schottky barrier height. The experimental I–V characteristics exhibited a Gaussian distribution having mean barrier heights {\\overline{{{Φ }}}}B of 0.30 eV and standard deviation σ s of 60 meV. Additionally, the Richardson modified constant was obtained to be 70 A cm‑2 K‑2, leading to an effective mass of 0.58m 0. Consequently, the temperature dependence of I–V characteristics of the SnO2 nanowire devices can be successfully explained on the Schottky–Mott theory framework taking into account a Gaussian distribution of barrier heights.

Facile synthesis of low-dimensional SnO2 nanostructures: An investigation of their performance and mechanism of action as anode materials for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Usman Hameed, Muhammad; Ullah Dar, Sami; Ali, Shafqat; Liu, Sitong; Akram, Raheel; Wu, Zhanpeng; Butler, Ian S.

2017-07-01

Owing to high-energy density of rechargeable lithium-ion batteries (LIBs), they have been investigated as an efficient electrochemical power sources for various energy applications. High theoretical capacities of tin oxide (SnO2) anodes have led us a path to meet the ever-growing demands in the development of high-performance electrode materials for LIBs. In this paper, a facile approach is described for the synthesis of porous low-dimensional nanoparticles and nanorods of SnO2 for application in LIBs with the help of Tween-80 as a surfactant. The SnO2 samples synthesized at different reaction temperatures produced porous nanoparticles and nanorods with average diameters of 7-10 nm and 70-110 nm, respectively. The SnO2 nanoparticle electrodes exhibit a high reversible charge capacity of 641.1 mAh/g at 200 mA/g after 50 cycles, and a capacity of 340 mAh/g even at a high current density of 1000 mA/g during the rate tests, whereas the porous nanorod electrodes delivers only 526.3 mAh/g at 200 mA/g after 50 cycles and 309.4 mAh/g at 1000 mA/g. It is believed that finer sized SnO2 nanoparticles are much more favorable to trap more Li+ ion during electrochemical cycling, resulting in a large irreversible capacity. In contrast, rapid capacity fading was observed for the porous nanorods, which is the result of their pulverization resulting from repeated cycling.

Influence of Water Vapors and Hydrogen on the Energy Band Bending in the SnO2 Microcrystals of Polycrystalline Tin Dioxide Films

NASA Astrophysics Data System (ADS)

Gaman, V. I.; Almaev, A. V.; Sevast'yanov, E. Yu.; Maksimova, N. K.

2015-06-01

The results of studying the dependence of the energy band bending at the interface of contacting SnO2 microcrystals in the polycrystalline tin dioxide film on the humidity level of clean air and hydrogen concentration in the gas mixture of clean air + H2 are presented. The experimental results showed that the bending of energy bands in SnO2 is decreased under exposure to the water vapors and molecular hydrogen. The presence of two types of the adsorption centers for water molecules on the surface of SnO2 is found. It is shown that at the absolute humidity of the gas mixture above 12 g/m3, the H2O and H2 molecules are adsorbed on the same centers, whose surface density is of 1012 сm-2 at a concentration of donor impurity in SnO2 equal to 1018 сm-3.

Design and assembly of ternary Pt/Re/SnO2 NPs by controlling the zeta potential of individual Pt, Re, and SnO2 NPs

NASA Astrophysics Data System (ADS)

Drzymała, Elżbieta; Gruzeł, Grzegorz; Pajor-Świerzy, Anna; Depciuch, Joanna; Socha, Robert; Kowal, Andrzej; Warszyński, Piotr; Parlinska-Wojtan, Magdalena

2018-05-01

In this study Pt, Re, and SnO2 nanoparticles (NPs) were combined in a controlled manner into binary and ternary combinations for a possible application for ethanol oxidation. For this purpose, zeta potentials as a function of the pH of the individual NPs solutions were measured. In order to successfully combine the NPs into Pt/SnO2 and Re/SnO2 NPs, the solutions were mixed together at a pH guaranteeing opposite zeta potentials of the metal and oxide NPs. The individually synthesized NPs and their binary/ternary combinations were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDS) analysis. FTIR and XPS spectroscopy showed that the individually synthesized Pt and Re NPs are metallic and the Sn component was oxidized to SnO2. STEM showed that all NPs are well crystallized and the sizes of the Pt, Re, and SnO2 NPs were 2.2, 1.0, and 3.4 nm, respectively. Moreover, EDS analysis confirmed the successful formation of binary Pt/SnO2 and Re/SnO2 NP, as well as ternary Pt/Re/SnO2 NP combinations. This study shows that by controlling the zeta potential of individual metal and oxide NPs, it is possible to assemble them into binary and ternary combinations. [Figure not available: see fulltext.

In-Depth View of the Structure and Growth of SnO2 Nanowires and Nanobrushes.