Dispersed SnO2 Research Articles

A preparation strategy for highly reversible conversion reaction Tin dioxide/ Carbon anode: Simple, ultrafast and scalable

Combining nanoscale engineering and physical confinement approach to prevent aggregation is a reliable strategy to achieve fully reversible conversion reaction SnO2-based anode. However, the synthesis of such nanostructures relies on complex self-sacrificing template preparation and time-consuming thermal treatment processes, which limit the practical application of high-performance SnO2 anodes for lithium-ion batteries. Herein, we present a simple strategy for the in situ preparation of SnO2 quantum dots embedded in carbon martix using an inherently advantageous MOF template and ultrafast microwave-assisted treatment in a few seconds. (denoted as SnO2 QDs@C). The dispersed SnO2 quantum dots with precise size control (≈5 nm) in the nanostructure shorten the lithium ion transport distance and enhance the reaction kinetics. Meanwhile, the carbon matrix promotes electron transport and suppresses Sn coarsening, thus achieving a highly reversible conversion reaction. Consequently, the SnO2 QDs@C anode achieves a reversible capacity of 1337 mAh g-1 after 200 cycles at 0.2 A g-1 with a capacity retention rate of more than 80%. This preparation method can be extended to prepare other metal oxide quantum dots/ Carbon composites and is expected to be applied in a wide range of fields.

Enhanced Na-ion storage via creating smooth ions transportation pathways in a modified heterostructure

Sodium-ion batteries (SIBs) have drawn evolutionary attention due to the urgent requirements for renewable energy storage. Unfortunately, the cycle stability and rate capability of promising SnO2 materials are far from satisfactory. Herein, enhanced Na-ion storage via creating smooth ion transportation pathways in a modified heterostructure has been originally demonstrated. The tuned composite of uniformly dispersed SnO2 particles anchored on the surface of graphene nanosheets was prepared via a facile hydrothermal treatment with the help of iodine. Inspiringly, an anticipated Na-ion storage can be successfully achieved, with reversible Na-ion storage of 486.1 mA h g−1 at 50 mA g−1 and rate capability of 343.8 mA h g−1 even at 800 mA g−1. The exceptional electrochemical property profited from the synergistic effect of the heterostructure with plentiful ion transportation pathways for fast Na-ion diffusion. This work opens a practical opportunity for the design of next-generation rechargeable batteries in energy storage.

Nano SnO2 loaded on N-doped carbon nanorods derived from metal-complex covalent organic frameworks for anode in lithium ion batteries

Covalent organic frameworks (COFs) with metal complexing ligand including COF-phen and COF-bpy have been designed and prepared, which can complex with Sn4+ to form COF-phen-Sn and COF-bpy-Sn, respectively. In this work, the metal ion complexed COFs are successfully employed as ideal precursors for the preparation of composite materials SnO2 @NCNR-x with nano SnO2 embedded within the rod-like N-doped carbonaceous materials. When employed as anode materials for lithium ion batteries (LIBs). SnO2 @NCNR-1 exhibited high reversible specific capacity (694.2 mA g−1 at 100 mA after 200 cycles, 506.5 mAh g−1 at 0.5 A g−1 after 600 cycles) owing to its high specific area, highly dispersed SnO2 nanoparticles and improved conductivity, recommending SnO2 @NCNR-1 to be a prospective candidate for LIBs.

Low concentration CO gas sensor constructed from MoS2 nanosheets dispersed SnO2 nanoparticles at room temperature under UV light

In consideration of the different electron structure-associated physical properties and internal sensing merits of MoS2 and SnO2, this work reports a nanocomposite with unique structure of MoS2 nanosheets dispersed SnO2 nanoparticles. The sensing performance of MoS2/SnO2 sensor toward low concentration CO was investigated at room temperature under the UV light illumination. It was found that MoS2/SnO2 sensor shows improved CO gas response (R ~ 4.97 at 40 ppm CO) compared with pure SnO2 (R ~ 3.27 at 40 ppm CO), which is due to the unique structure and the formation of heterostructure between MoS2 and SnO2. Moreover, the fabricated sensor also exhibits fast response and recovery time (43 s/36 s). The sensor provides a potential platform for monitoring CO gas at room temperature.

Design of thin-film configuration of SnO2–Ag2O composites for NO2 gas-sensing applications

Abstract In this study, a two-layered thin-film structure consisting of a dispersed nanoscaled Ag2O phase and SnO2 layer (SA) and a mono-composite film layer (CSA) consisting of a nanoscale Ag2O phase in the SnO2 matrix are designed and fabricated for NO2 gas sensor applications. Two-layered and mono-layered SnO2–Ag2O composite thin films were synthesized using two-step SnO2 and Ag2O sputtering processes and Ag2O/SnO2 co-sputtering approach, respectively. In NO2 gas-sensing measurement results, both SA and CSA thin films that functionalized with an appropriate Ag2O content exhibit enhanced gas-sensing responses toward low-concentration NO2 gas in comparison with that of pristine SnO2 thin film. In particular, a gas sensor made from the mono-composite SnO2–Ag2O layer demonstrates apparently higher NO2 gas-sensing performance than that of double-layered SnO2–Ag2O thin-film sensor. This is attributed to substantially numerous p–n junctions of Ag2O/SnO2 formed in the top region of the SnO2 matrix. The gas-sensing response of the optimal sample (CSA270) toward 10 ppm NO2 gas is 5.91, and the response/recovery speeds in a single cycle dynamic response plot are 28 s/168 s toward 10 ppm NO2, respectively. Such a p–n thin-film configuration is beneficial to induce large electric resistance variation before and after the introduction of NO2 target gas during gas-sensing tests. The experimental results herein demonstrate that the gas-sensing performance of p–n oxide composite thin films can be tuned via the appropriate design of composite thin-film configuration.

Defect engineered SnO2 nanoparticles enable strong CO2 chemisorption toward efficient electroconversion to formate.

Oxygen vacancy (Ov) engineering of SnO2 electrocatalysts plays a crucial role in realizing efficient CO2 electroreduction (CO2RR) into formate. Herein, we demonstrate the rational synthesis of highly dispersed SnO2 nanoparticle electrocatalysts with an ultrahigh Ov content of up to 25.1% by a thermally induced strategy. The high Ov content greatly improves the intrinsic conductivity and remarkably enhances the chemisorption capacity to CO2, thus boosting the catalytic activity and reaction kinetics of CO2 electroconversion into formate. These advantages make the Ov-engineered SnO2 electrocatalysts exhibit both a high Faraday efficiency (FE) of nearly 90% and a superior cathodic energy efficiency of above 60% to produce formate in a wide current range from 100 to 400 mA cm-2 in a flow cell. A commercially required current of 200 mA cm-2 can be obtained at only 2.8 V in a full cell. The present Ov engineering strategy exhibits the possibility for the design and construction of high-activity oxide-based electrocatalysts.

Assembling Ultrafine SnO2 Nanoparticles on MIL-101(Cr) Octahedrons for Efficient Fuel Photocatalytic Denitrification.

Effectively reducing the concentration of nitrogen-containing compounds (NCCs) remains a significant but challenging task in environmental restoration. In this work, a novel step-scheme (S-scheme) SnO2@MCr heterojunction was successfully fabricated via a facile hydrothermal method. At this heterojunction, MIL-101(Cr) octahedrons are decorated with highly dispersed SnO2 quantum dots (QDs, approximate size 3 nm). The QDs are evenly wrapped around the MIL-101(Cr), forming an intriguing zero-dimensional/three-dimensional (0D/3D) S-scheme heterostructure. Under simulated sunlight irradiation (280 nm < λ < 980 nm), SnO2@MCr demonstrated superior photoactivity toward the denitrification of pyridine, a typical NCC. The adsorption capacity and adsorption site of SnO2@MCr were also investigated. Tests using 20%SnO2@MCr exhibited much higher activity than that of pure SnO2 and MIL-101(Cr); the reduction ratio of Cr(VI) is rapidly increased to 95% after sunlight irradiation for 4 h. The improvement in the photocatalytic activity is attributed to (i) the high dispersion of SnO2 QDs, (ii) the binding of the rich adsorption sites with pyridine molecules, and (iii) the formation of the S-scheme heterojunction between SnO2 and MIL-101(Cr). Finally, the photocatalytic mechanism of pyridine was elucidated, and the possible intermediate products and degradation pathways were discussed.

Synthesis and characterization of long-term stable aqueous colloidal dispersed Sb-doped SnO2

Synthesis and characterization of long-term stable aqueous colloidal dispersed Sb-doped SnO2

Expounding the monolayer dispersion threshold effect of SnO2/Beta catalysts on the selective catalytic reduction of NOx (NOx-SCR) by C3H6

Abstract To develop applicable catalysts for NOx-SCR by C3H6, SnO2/Beta catalysts with different loadings have been fabricated. The monolayer dispersion behavior of SnO2 on H-Beta zeolite support have been explored thoroughly by using different characterization techniques. SnO2 can spontaneously dispersed on H-Beta zeolite support with a capacity of 0.291 mmol SnO2 per 100 m2, equaling to 16 wt.% SnO2 loading. Below the capacity, SnO2 is present in a sub-monolayer state, and has a close interaction with the support by donating electrons from Sn4+ in SnO2 to Si4+ in H-Beta zeolite. The sub-monolayer/monolayer dispersed SnO2 facilitates the formation of more surface vacancies, active superoxide anions and acid sites, which are important for the reactivity. As a consequence, 15% SnO2/Beta with nearly the threshold amount of SnO2 owns the biggest quantities of the two kinds of surface reactive sites, thus demonstrating the best reaction performance in the samples. It is discovered that selective NOx reduction by C3H6 over SnO2/Beta mainly follows a Langmuir-Hinselwood mechanism, in which surface formate/acetate and monodentate nitrate are the major reactive intermediates.

Confined Generation of Homogeneously Dispersed Au and SnO2 Nanoparticles in Layered Silicate as Synergistic Catalysts.

With the aid of the confined conversion of layered silicate RUB-15, homogeneously dispersed Au and SnO2 nanoparticles (NPs) were generated in the confined layer space of RUB-15. The Au-SnO2/SiO2 composite was obtained with the structure that ultrafine Au and SnO2 NPs were supported on SiO2 lamellas. Benefited by the Sn(II)-assisted in situ reduction strategy, Au NPs were highly uniformed and evenly distributed in/on the RUB-15. This Au-SnO2/SiO2 composite was employed as a catalyst to the reduction of 4-nitrophenol showing excellent catalytic activity. The catalytic rate constant at room temperature was calculated to be 6.64 min-1, which was dramatically higher than that of Au/SiO2 composite produced by reduction with hydrazine hydrate on the same support of layered silicate RUB-15. The interaction between Au and SnO2 NPs increased the electron density around Au NPs, which was demonstrated to be an essential factor to the excellent catalytic activity of the Au-SnO2/SiO2 composite. The simple and universal synthesis method afforded precise control over the size/spatial arrangement of Au and SnO2 NPs on SiO2 lamellas. The high activity of the Au-SnO2/SiO2 composite demonstrated that the strategy used in this study has good potential application prospect. Furthermore, this work provided new perspective on the catalysis mechanism to the metal/semiconductor synergistic catalyst system.

SnO2 nanoparticles embedded in 3D hierarchical honeycomb-like carbonaceous network for high-performance lithium ion battery

A honeycomb-like composite of SnO2 nanoparticles decorated 3D carbon network (H-SnO2@3DC) is synthesized via an all-in-one route, where the assembling of structural directing NaCl templates and the in-situ freeze-drying followed by pyrolysis growth of 2D carbon sheets encapsulated SnO2 nanoparticles are involved. The carbon network with high porosity endows the composite with high conductivity and buffers the volume change, whereas the homogenously dispersed SnO2 nanoparticles work as active sites to store Li+. The Li-ion battery (LIB) employed the as-obtained composite anode materials exhibits a high reversible capacity of 798 mA h g−1 at 1 A g−1 over 1000 cycles and an enhanced rate capability of 374 mA h g−1 at 5 A g−1, demonstrating the unique synergism of the above 3D hierarchical honeycomb-like structure. This synthetic strategy provides an inspiration to prepare other metallic oxides/sulfides anode with problems of volume expansion or poor conductivity for alkali ion storage.

Highly dispersed SnO2 nanoparticles confined on xylem fiber-derived carbon frameworks as anodes for lithium-ion batteries

Abstract Tin oxide (SnO2) has been considered as a promising alternative material for lithium-ion batteries (LIBs) anodes owing to its high specific capacity, low operation potential and high natural abundance. However, its practical performance is hampered by the poor rate capability and fast capacity fading. In this work, we synthesized the highly dispersed SnO2 nanoparticles confined on the xylem fiber-derived carbon frameworks (SnO2@XFC@C) by a facile solvothermal method. The synergy of using open XFs-derived carbon as conductive framework and glucose-derived carbon as matrix enables the superior lithium storage capability of SnO2 materials. Using aqueous electrode proceeding, the SnO2@XFC@C delivers a high discharge capacity of 1810 mAh g−1 with an initial Coulombic efficiency of 85.4%, and excellent high-rate cycling stability (505 mAh g−1 at 1.0 C after 1000 cycles). This structure design offers significant advantages in terms of realization of low cost, high energy and sustainable lithium-ion batteries, and is extendable to other battery systems.

Physicochemical characteristics and photocatalytic performance of Tin oxide/montmorillonite nanocomposites at various Sn/montmorillonite molar to mass ratios

Nanocomposites of tin oxide immobilized in montmorillonite (Mt) with various Sn/Mt. mole-to-mass ratios were prepared for photocatalysis application. The prepared samples were characterized by x-ray diffraction, transmission electron microscopy, N2 adsorption–desorption analysis, and diffuse reflectance UV–visible spectroscopy. The relationships between the physicochemical characteristics and photocatalytic activities of the materials were evaluated in terms of rhodamine B photocatalytic degradation. From the results, the samples showed that the Sn/ Mt. mole-to-mass ratio affects the increase in the interlayer space of the montmorillonite structure, and the particle size of the dispersed SnO2 nanoparticles increases with increasing ratio, ranging from 10 to 50 nm. The BET specific surface area, pore volume, and band gap energy of the nanocomposites are related with the structural changes, which are closely related with the SnO2 content. The materials exhibit excellent photocatalytic activity as indicated by their higher turnover number and degradation efficiency than those of SnO2 and related photocatalysts. Statistical optimization of the effect of the physicochemical characteristics of the photocatalyst on photocatalytic activity by using the logit model revealed that SnO2 and pH affect the degradation efficiency and initial rate of rhodamine B degradation.

Effect of Stannic Species Modification on the Acidity of Silicalite-1 and Its Enhancement in Transforming Ethylenediamine to Heterocyclic Amines

In this study, a series of SnO2 modified zeolite catalysts (Snx-S-1; x is the weight percentage of Sn) were prepared with SnCl2 and a defective Silicalite-1 (S-1) zeolite via facile deposition–precipitation method. It was found that the stannic species modified all-silica zeolite catalysts were active for the intermolecular condensation of ethylenediamine (EDA) to 1, 2-Diazabicyclo [2, 2, 2] octane (TEDA) and piperazine (PIP). The best catalyst Sn6-S-1 (6 wt.% Sn loading) showed 86% EDA conversion and 93% total selectivity to TEDA and PIP. By contrast, the defective S-1 zeolite parent showed only approximately 9% EDA conversion under the same conditions. With the help of catalyst characterization techniques including hydroxyl vibration and pyridine adsorption FT-IR spectroscopy (transmission mode), the enhancement of the catalytic activity of the SnO2 modified zeolite catalysts (Snx-S-1) was mainly attributed to the formation of mild Lewis acid sites in the siliceous zeolite. Both the hydroxyl nests of the defective S-1 zeolite and the dispersed SnO2 clusters should be the important factors for the formation of mild Lewis acid sites on the modified zeolite. Based on the catalytic performance of the modified zeolite in the conversion of EDA to PIP and TEDA, it is inferred that the mildly acidified defective S-1 zeolite by the SnO2 deposition modification might become a very active and durable catalyst for reactions involving strongly alkaline reactants and products.

Facile synthesis and characterization of Chrysotile/SnO2 nanocomposite for enhanced photocatalytic properties

AbstractSnO2 nanocrystals grown on chrysotile surfaces could be facilely synthesized in large quantities through a direct precipitation process coupled with a calcination treatment. The as‐synthesized chrysotile/SnO2 nanocomposites showed a smaller band gap energy (2.88 ev) and relatively strong light absorption than the individually dispersed SnO2 nanocrystals. Due to the narrow gap and chemical passivation aroused by inherently negative charges on the surface of chrysotile, chrysotile/SnO2 nanocomposite was endowed with superior performance to chrysotile nanotube and SnO2 nanocrystals.

Free-Standing SnO2@rGO Anode via the Anti-solvent-assisted Precipitation for Superior Lithium Storage Performance.

Metal oxides have been attractive as high-capacity anode materials for lithium-ion batteries. However, oxide anodes encounter drastic volumetric changes during lithium ion storage through the conversion reaction and alloying/dealloying processes, leading to rapid capacity decay and poor cycling stability. Here, we report a free-standing SnO2@reduced graphene oxide (SnO2@rGO) composite anode, in which SnO2 nanoparticles are tightly wrapped within wrinkled rGO sheets. The SnO2@rGO sheet is assembled in high porosity via an anti-solvent-assisted precipitation of dispersed SnO2 nanoparticles and graphene oxide sheets in the distilled water, followed by the filtration and post-annealing processes. Significantly enhanced lithium storage performance has been obtained of the SnO2@rGO anode compared with the bare SnO2 anode material. A high charge capacity above 700 mAh g−1 can be achieved with a satisfying 95.6% retention after 50 cycles at a current density of 500 mA g−1, superior to reserved 126 mAh g−1 and a much lower 16.8% retention of the bare SnO2 anode. XRD pattern and HRTEM images of the cycled SnO2@rGO anode material verify the expected oxidation of Sn to SnO2 at the fully-charged state in the 50th cycle. In addition, FESEM and TEM images reveal the well-preserved free-standing structure after cycling, which accounts for high reversible capacity and excellent cycling stability of such a SnO2@rGO anode. This work provides a promising SnO2-based anode for high-capacity lithium-ion batteries, together with an effective fabrication adoptable to prepare different free-standing composite materials for device applications.

Implementation of Tin Dioxide/Graphene/Graphene Oxide for High Capacity and Long Cycle Life Lithium Ion Batteries

We explored a non-conventional process to synthesize SnO2/G/GO composite powder which is a conformal structure that was characterized under different techniques. Comprehensive analysis of the structural and chemical properties reveals that the material consists of highly dispersed SnO2 nanoparticles in G/GO matrix. We examine the electrical conductivity of the electrodes by atomic force microscope (AFM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The SnO2/G/GO composite exhibited high discharge capacity and excellent electrochemical performance as anode material for lithium ion Battries. The quantitative/qualitative results show that G/GO is providing contact areas which results in more energy density at the interface electrode/electrolyte and that the SnO2 provides additional ions to the EDL and the electrochemical process.

Facile and in-situ spray deposition of SnO2 – reduced graphene oxide heterostructure sensor devices

A facile and economic solution based technique is developed for the deposition of SnO2—Reduced Graphene Oxide (RGO) heterostructure thin films. The single step deposition process leads to uniformly dispersed SnO2 nanocrystallites on well exfoliated RGO sheets as confirmed by x-ray diffraction, Raman spectroscopy and transmission electron microscopy investigations. The response to NO2 gas at room temperature (25 °C) is studied. The interface between n-type SnO2 and p-type RGO flakes forms a hetrostrcuture barrier, which enhances the native sensitivity of pristine RGO towards toxic gases like NO2. The technique allows controlling the density of SnO2 nanoparticles (∼3 nm in size) attached to the RGO flakes and thereby enhancing the response of the heterostructure sensor device. The highest SnO2 loading shows a 14 fold increase in response to 200 ppm of NO2 and a response time as low as 5 s compared to that of ∼200 s for bare RGO films.

The ensemble effect of nitrogen doping and ultrasmall SnO2 nanocrystals on graphene sheets for efficient electroreduction of carbon dioxide

The electroreduction of carbon dioxide (CO2) into fuels and other chemicals is an exciting approach to address the urgent climate and energy challenges. However, the unsatisfied efficiency and selectivity for CO2 reduction reaction (CO2RR) with conventional electrocatalysts are the major obstacles. Herein, a facile and effective method is developed to deposit ultrasmall SnO2 nanocrystals on nitrogen-doped graphene via in-situ conversion strategies for highly efficient CO2RR. The comparison studies reveal that the electrocatalytic activity of such electrocatalysts relies on the loading of SnO2 on graphene and the nitrogen doping. The optimal electrocatalyst exhibits a high selectivity for CO2 electroreduction to formate and carbon monoxide at low overpotential (∼ 0.6 V) with a faradaic efficiency of ∼ 89% and a current density of ∼21.3 mA/cm2. Additionally, the optimal electrocatalyst shows an excellent stability for 20 h. The good performance would be contributed to the ensemble effect between the highly dispersed ultrasmall SnO2 nanocrystals and the nitrogen doping on graphene sheets. This work thus provides a rational design strategy for developing efficient CO2 reduction catalysts.

Selective conversion of concentrated glucose to 1,2-propylene glycol and ethylene glycol by using RuSn/AC catalysts

A series of RuSn/AC catalysts with 5% Ru and 1–6% Sn loadings were synthesized for converting concentrated (10 wt%) sugars to 1,2-propylene glycol (1,2-PG) and ethylene glycol (EG) in a semi-continuous autoclave reactor. The catalysts structure and the product distributions are found to be highly dependent on the tin loading. At tin contents below 2%, RuSn alloy was formed coexisting with small amounts of highly dispersed SnO2 in the catalyst, and hexitols were the main products due to the high activity of catalysts for hydrogenation. At a tin content above 5%, more SnO2 species were present and covered RuSn alloy particles, leading to notable amounts of humins in the reaction due to the depressed hydrogenation activity. As for the optimal catalyst of 5%Ru3%Sn/AC, 77% of tin formed RuSn alloy with ruthenium and 23% of tin existed in the form of highly dispersed SnO2 under reaction conditions. The catalyst gave 25% and 26.9% yields of 1,2-PG and EG in the glucose conversion at 513 K for 10 min. The glycols yield was insensitive to the feeding rate of glucose, which could be increased to 10 mL/min with a glycols productivity of nearly 180 g L−1 h−1. The catalysts structure and reaction networks were proposed according to pseudo in situ characterizations and conditional experiments. The highly dispersed SnO2 was effective to sugar isomerization and the RuSn alloy played the major role in retro-aldol condensation and hydrogenation reactions. Over the 5%Ru3%Sn/AC catalyst, the rates of cascade reactions of isomerization, retro-aldol condensation and hydrogenation matched well due to the balanced activity of RuSn alloy and highly dispersed SnO2, which afforded a high yield of 1,2-PG and EG.