SnO2 Hollow Spheres Research Articles

Hierarchical Double‐Shell Nanostructures of TiO2 Nanosheets on SnO2 Hollow Spheres for High‐Efficiency, Solid‐State, Dye‐Sensitized Solar Cells

A high‐energy conversion efficiency of 8.2% at 100 mW cm−2 is reported, one of the highest values for N719‐based, solid‐state, dye‐sensitized solar cells (ssDSSCs). The solar cells are based on hierarchical double‐shell nanostructures consisting of inner SnO2 hollow spheres (SHS) surrounded by outer TiO2 nanosheets (TNSs). Deposition of the TNS on the SHS outer surface is performed via solvothermal reactions in order to generate a double‐shell SHS@TNS nanostructure that provides a large surface area and suppresses recombination of photogenerated electrons. An organized mesoporous (OM)‐TiO2 film with high porosity, large pores, and good interconnectivity is also prepared via a sol‐gel process using a poly(vinyl chloride)‐g‐poly(oxyethylene methacrylate) (PVC‐g‐POEM) graft copolymer template. This film is utilized as a matrix to disperse the double‐shell nanostructures. Such nanostructures provide good pore‐filling for solid polymer electrolytes, faster electron transfer, and enhanced light scattering, as confirmed by reflectance spectroscopy, incident photon‐to‐electron conversion efficiency (IPCE), and intensity‐modulated photocurrent spectroscopy (IMPS)/intensity‐modulated photovoltage spectroscopy (IMVS).

Poly(3,4-ethylenedioxythiophene) Sheath Over a SnO2 Hollow Spheres/Graphene Oxide Hybrid for a Durable Anode in Li-Ion Batteries

SnO2 hollow spheres (HSs) were synthesized by a hydrothermal route by use of an organic additive (2-mercaptopropionic acid or MPA) and a cationic surfactant (cetyltrimethyl ammonium bromide or CTAB). The progressive transformation of SnO2 solid spheres to SnO2 HSs 140–150 nm in dimensions wherein a thin shell of densely packed SnO2 crystallites with a tetragonal crystal structure surrounds an empty core was followed by scanning- and transmission-electron microscopy. The roles of MPA as the HS structure-directing agent, CTAB as the moiety which prevents HS aggregation, and water as the solvent crucial for hollow core formation were independently determined by elaborate morphological analyses. With the goal of realizing superior electrochemical performance, hybrids of optimized SnO2 HSs embedded in graphene oxide (GO) nanosheets and enveloped by a sheath of a conducting polymer, poly(3,4-ethylenedioxythiophene) or PEDOT, were also synthesized; the continuity of the amorphous PEDOT coating on SnO2 HS/GO was confirmed by elemental mapping and X-ray photoelectron spectroscopy. Galvanostatic charge–discharge studies revealed an initial reversible capacity of 990 mA h g–1 for SnO2 HSs at a current density of 100 mA g–1, and a capacity of 400 mA h g–1 was retained after 30 cycles. A significant improvement in cycling performance was achieved in the SnO2 HS/GO/PEDOT hybrid, as the synergy between the moderately high intrinsic electronic conductivity of GO nanosheets and the ability of PEDOT to buffer the volume change during repetitive Li+ charge–discharge more efficiently compared to pristine SnO2 HS impart a capacity of 608 mA h g–1 at a current density of 100 mA g–1 to the hybrid, retained at the end of 150 cycles, and the latter value was ∼1248 mA h g–1 when the mass of only the SnO2 HS in the hybrid was considered. The SnO2 HS/GO/PEDOT hybrid also showed an excellent rate capability as a capacity of 381 mA h g–1 was attained even at a high current density of 2000 mA g–1. We demonstrate the viability of the SnO2 HS/GO/PEDOT hybrid as a durable high performance anode for Li-ion batteries.

Core–shell structured hollow SnO2–polypyrrole nanocomposite anodes with enhanced cyclic performance for lithium-ion batteries

Core–shell structured hollow SnO2–polypyrrole (PPy) nanocomposites (SnO2@PPy) with excellent electrochemical performance were synthesized using a hydrothermal method followed by an in situ chemical-polymerization route. The thickness of the polymerized amorphous PPy coating covering on the hollow SnO2 microspheres is about 25nm, demonstrated by microscopy images. As an anode in lithium ion batteries, the nanocomposite is capable of retaining a high capacity of 448.4mAhg−1 after 100 cycles with a coulomb efficiency above 97%. Compared to other reported SnO2 anodes, the enhanced cycling stability is attributed to the unique core–shell structure and a possible synergistic effect between the PPy coating layer and the hollow SnO2 spheres. The PPy coating not only prevents the possible pulverization of the hollow SnO2 spheres, but also prevents the SnO2/Sn spheres from aggregating. Furthermore, the hollow space within the SnO2 nanoparticles effectively mitigates the enormous volume change during charge–discharge cycling. Meanwhile, the Li+ diffusion coefficient in the hollow SnO2@PPy (21wt%) core–shell nanocomposite electrode is significantly improved compared to the hollow SnO2 microspheres electrode. Thus, these benefits from the PPy coating and the hollow SnO2 spheres are able to provide a robust architecture for lithium-ion battery anodes.

Ultraselective and ultrasensitive detection of H2S in highly humid atmosphere using CuO-loaded SnO2 hollow spheres for real-time diagnosis of halitosis

The CuO-loaded SnO2 hollow spheres were prepared by ultrasonic spray pyrolysis and their H2S sensing characteristics in dry and humid atmospheres for the diagnosis of halitosis were investigated. The loading of CuO to SnO2 hollow spheres decreased the humidity dependence of H2S sensing characteristics down to negligible level, increased the gas response (ratio of resistance to air and gas) in highly humid atmosphere (relative humidity 80%) to 1ppm H2S from 3.13 to 22.4, and enhanced the selectivity to H2S over CO, NH3, CH3COCH3, C6H6, CH3C6H5, (CH3)2C6H4, and NO at 300°C. Ultraselective and ultrasensitive detection of H2S under highly humid atmosphere with negligible interferences from other biomarker gases provides a promising and reliable analysis tool for real-time diagnosis of halitosis from exhaled breath.

Size-controlled SnO₂ hollow spheres via a template free approach as anodes for lithium ion batteries.

Tin oxide hollow spheres (SnO₂ HS) with high structural integrity were synthesized by using a one pot hydrothermal approach with organic moieties as structure controlling agents. By adjusting the proportion of acetylacetone (AcAc) in the precursor formulation, SnO₂ HS of 200 and 350 nm dimensions, with a uniform shell thickness of about 50 nm, were prepared. Using the optimized solution composition with a Sn precursor, heating duration dependent structural evolution of SnO₂ was performed at a fixed temperature of 160 °C, which revealed a transition from solid spheres (1 h) to aggregated spheres (4 h) to porous spheres (10 h) to optimized HS (13 h) and finally to broken enlarged HS (24 h). A heating temperature dependent study carried out with a constant heating span of 13 h showed a metamorphosis from spheres with solid cores (140 °C) to ones with hollow cores (160 °C), culminating with fragmented HS, expanded in dimensions (180 °C). A growth mechanism was proposed for the optimized SnO₂ HS (2.5 or 5.0 mL of AcAc, 160 °C, 13 h) and the performance of these HS as anodes for Li ions batteries was evaluated by electrochemical studies. The 200 nm SnO₂ HS demonstrated an initial lithium storage capacity of 1055 mA h g(-1) at a current density of 100 mA g(-1), and they retained a capacity of 540 mA h g(-1) after 50 charge-discharge cycles. The SnO₂ HS also showed excellent rate capability as the electrode exhibited a capacity of 422 mA h g(-1) even at a high current density of 2000 mA g(-1). The notable capacity of SnO₂ HS is a manifestation of the mono-disperse quality of the SnO₂ HS coupled with the high number of electrochemically addressable sites, afforded by the large surface area of the HS and the striking cyclability is also attributed to the unique structure of HS, which is resistant to degradation upon repeated ion insertion/extraction. The SnO₂ HS were also found to be luminescent, thus indicating their usefulness for not only energy storage but also for energy harvesting applications.

Hollow SnO2/α-Fe2O3spheres with a double-shell structure for gas sensors

Double-shell SnO2/α-Fe2O3 hollow composites were synthesized by a low-cost and environmentally friendly hydrothermal strategy. Various techniques were employed for the characterization of the structure and morphology of hybrid nanostructures. The results revealed that the α-Fe2O3 nanorods grew epitaxially on the surface of hollow SnO2 spheres, which were composed of primary nano-sized particles. The diameter of the α-Fe2O3 nanorods was about 10 nm, and the thickness of the SnO2 spherical shell was about 100 nm. In order to explore the formation mechanism of the composites, the structure features of the double-shell structural SnO2/α-Fe2O3 hollow composites at different reaction stages were investigated. The ethanol sensing properties of the pure SnO2 and SnO2/α-Fe2O3 composites were tested. It was found that such double-shell composites exhibited enhanced ethanol sensing properties compared with the single-component SnO2 hollow spheres. For example, at an ethanol concentration of 100 ppm, the response of the SnO2/α-Fe2O3 composites was about 16, which was about 2 times higher than that of the primary SnO2 nanostructures. The response time of the sensor to 10 ppm ethanol was about 1 s at the operating temperature of 250 °C.

Lithium storage improvement from hierarchical double-shelled SnO2 hollow spheres

We have developed hierarchical double-shelled SnO2 hollow spheres by a sequential template-engaged method, in which the loosened SnO2 floccules are well-grown on the inside wall of the hollow spheres.

Hollow SnO2 microspheres and their carbon-coated composites for supercapacitors

In the presence of sulfonated polystyrene (sPS) template, sPS@SnO2 core shell particles formed via the interaction between the functional group of -SO3H on the template surface and ions of Sn2+ from the precursor of SnSO4 which were in ethanol-aqueous medium. After high-temperature calcination treatment for removal of sPS, the sPS@SnO2 changed into SnO2 hollow spheres. With the further carbonization of the sPS@SnO2@glucose composite microspheres, SnO2@C composite hollow spheres were fabricated. Using SEM, TEM, and N2 adsorption - desorption technology, the structure, specific surface area, and the core-shell structure formation mechanism were determined. Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) properties of SnO2 hollow spheres and SnO2@C composites were investigated, respectively, in the foam nickel electrode under alkaline condition. The specific capacitance of SnO2@C composite hollow spheres could reach 25.8Fg−1 in 1molL−1 KOH aqueous solution and showed excellent charge-discharge behavior.

Cauliflower-like SnO2 hollow microspheres as anode and carbon fiber as cathode for high performance quantum dot and dye-sensitized solar cells

Cauliflower-like tin oxide (SnO2) hollow microspheres (HMS) sensitized with multilayer quantum dots (QDs) as photoanode and alternative stable, low-cost counter electrode are employed for the first time in QD-sensitized solar cells (QDSCs). Cauliflower-like SnO2 hollow spheres mainly consist of 50 nm-sized agglomerated nanoparticles; they possess a high internal surface area and light scattering in between the microspheres and shell layers. This makes them promising photoanode material for both QDSCs and dye-sensitized solar cells (DSCs). Successive ionic layer adsorption and reaction (SILAR) method and chemical bath deposition (CBD) are used for QD-sensitizing the SnO2 microspheres. Additionally, carbon-nanofiber (CNF) with a unique structure is used as an alternative counter electrode (CE) and compared with the standard platinum (Pt) CE. Their electrocatalytic properties are measured using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and Tafel-polarization. Under 1 sun illumination, solar cells made with hollow SnO2 photoanode sandwiched with the stable CNF CE showed a power conversion efficiency of 2.5% in QDSCs and 3.0% for DSCs, which is quite promising with the standard Pt CE (QDSCs: 2.1%, and DSCs: 3.6%).

Electrochemical performance of SnO2–Fe2O3 hollow spheres prepared by solid acid template method

SnO2–Fe2O3 hollow spheres are fabricated with solid acid sphere as template, which presented excellent electrochemical performances with capacity of 595.5mAhg−1 at 0.2C (160mAg−1) in the potential range of 0.05–1.2V (vs. Li+/Li), upon 50 cycles, the capacity retentions is 96.9%. Compared with SnO2 hollow spheres, SnO2–Fe2O3 hollow spheres electrode has an improved rate capability, when charged at 10C (8000mAg−1), the capacity can reach 400mAhg−1, which is about 67% of that at 0.2C. This excellent high rate performance of SnO2–Fe2O3 material is related to the reduction of Fe2O3 in the initial discharge process, the hollow structure and the constructing particles with nanosize, which help to improve the electronic conductivity, buffer the huge volume change and stabilize the structure.

The preparation of double-void-space SnO2/carbon composite as high-capacity anode materials for lithium-ion batteries

In this work, double-void-space SnO2/carbon composite has been synthesized as high-capacity anode materials for lithium-ion batteries. This novel designed structure, with the internal void space inside SnO2 hollow spheres and the external void space between SnO2 and carbon, can superiorly accommodate the large volume change as a physical buffering layer during the charge/discharge procedure. It is found that the double-void-space SnO2/carbon composite manifest a much higher reversible capacity compared to SnO2 hollow spheres. Due to the formation of the void space, the special composite is able to deliver a reversible Li storage capacity of 408.4 mAh g−1 after 50 cycles. This implies the structural optimization can provide new opportunities to enhance the properties of tin-based materials for high-capacity lithium-ion batteries.

Efficient Light Scattering from Nanochains Encapsulated in SnO2 Hollow Spheres

Efficient Light Scattering from Nanochains Encapsulated in SnO2 Hollow Spheres

ChemInform Abstract: Confining Sulfur in Double‐Shelled Hollow Carbon Spheres for Lithium—Sulfur Batteries.

AbstractNew sulfur—carbon nanocomposites are prepared by confining sulfur in double‐shelled hollow carbon spheres, which are obtained from SnO2 hollow spheres dispersed in aqueous glucose solution (autoclave, 180 °C, 4 h).

The preparation of uniform SnO2 nanotubes with a mesoporous shell for lithium storage

Uniform SnO2 nanotubes with a mesoporous shell were successfully prepared by calcination of SnO2@polymeric nanotubes. The SnO2 nanotubes possess enhanced lithium storage performance compared with SnO2 hollow spheres and SnO2 nanoparticles owing to the unique structure of mesoporous shell, open ends and hollow interior.

Palladium nanoparticles on the inner wall of tin oxide hollow nanospheres with enhanced hydrogen sensing properties

A Pd@SnO2 composite with the unique structure of Pd nanoparticles loaded on the inner wall of SnO2 hollow nanospheres was fabricated through a simple multi-step method. This Pd@SnO2 composite was used as a functional material for gas sensing. Compared to SnO2 hollow spheres, the Pd@SnO2 composite showed enhanced hydrogen sensing properties.

Synthesis of SnO2 nano hollow spheres and their size effects in lithium ion battery anode application

Nano-sized SnO2 hollow spheres are facilely synthesized by sol–gel method using the SiO2 nanospheres as sacrificed templates, and their electrochemical properties are investigated as an anode application for lithium ion battery (LIB). The size of the hollow spheres is controlled by using different-sized templates. As-coated SnO2 shell is almost amorphous and transformed into a rutile phase after annealing at 600 °C. The size of the SnO2 hollow spheres ranges from 25 to 100 nm. The shell thickness is almost constant (∼5 nm) irrespective of the size of the hollow spheres. The hollow spheres showed the size dependent electrochemical properties, and the smallest SnO2 (25 nm) hollow sphere exhibited a high reversible capacity of 750 mAh g−1 as well as excellent cyclability.

Confining Sulfur in Double‐Shelled Hollow Carbon Spheres for Lithium–Sulfur Batteries

New sulfur—carbon nanocomposites are prepared by confining sulfur in double-shelled hollow carbon spheres, which are obtained from SnO2 hollow spheres dispersed in aqueous glucose solution (autoclave, 180 °C, 4 h).

Preparation, characterization and acetone sensing properties of Ce-doped SnO2 hollow spheres

Abstract The Ce-doped SnO2 hollow spheres were prepared by the uniform coating of Ce and Sn precursors onto polystyrene (PS) spheres, following by heat treatment at 550 °C to remove the PS spheres core. The observations of field emission gun scanning electron microscope (FESEM) and transmission electron microscopy (TEM) showed that Ce-doped SnO2 hollow spheres with a shell thickness of ∼200 nm, which were composed of nanoparticle aggregates with the crystallite size of 10–15 nm. X-ray diffraction (XRD) exhibited that all the diffraction peaks have been indexed to a rutile structure of SnO2. No diffraction peaks of cerium oxide were observed, suggesting that Ce4+ ions get uniformly substituted into the Sn4+ sites or interstitial sites in SnO2 lattice. The Ce-doped SnO2 hollow spheres showed perfect sensing performance toward acetone gas with rapid response, good stability and high response at 250 °C compared with pure SnO2 hollow spheres.

SnO2 hollow spheres: Polymer bead-templated hydrothermal synthesis and their electrochemical properties for lithium storage

SnO2 hollow spheres have been synthesized via a facile hydrothermal method using sulfonated polystyrene beads as a template followed by a calcination process in air. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy show that the as-obtained SnO2 hollow spheres have a wall thickness of about 50 nm, and consist of nanosized SnO2 particles with a mean diameter of about 15 nm. Electrochemical measurements indicate that the SnO2 hollow spheres exhibit improved electrochemical performance in terms of specific capacity and rate capability in comparison with commercial SnO2 when used as anode materials for lithium-ion batteries. The enhanced performance may be attributed to the spherical and hollow structure, as well as the building blocks of SnO2 nanoparticles.

Synthesis of SnO2 nanorods and hollow spheres and their electrochemical properties as anode materials for lithium ion batteries

SnO2 nanorods and hollow spheres were conducted via a surfactant assisted hydrothermal reaction with the hydrothermal temperature. The crystalline structure and morphologies of the as prepared samples were characterised by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate that the products are hollow spheres with diameters of approximately 400–800 nm and shell thicknesses of 60–70 nm via hydrothermal treating at 160°C for 42 h and rod-like nanostructures with diameters of ∼30 nm and lengths of 100–300 nm via hydrothermal treating at 200°C for 42 h respectively. The as prepared samples were used as anode materials for lithium ion battery, whose charge–discharge properties and cycle performance were examined. The results show that the initial discharge capacities of SnO2 hollow spheres and SnO2 nanorods samples are 1303 and 1426 mA h g−1 at 0·2C rate, and still retain charge capacities of 518 and 578 mA h g−1 respectively. Its good cycling behaviour and charge capacities make it a promising cathode material for advanced electrochemical devices for lithium ion batteries.