Bare SnO2 Research Articles

A Featural Analysis of Aluminium Doped SnO2 and Bare SnO2 Thin Films Grown on FTO Substrates

Nanomaterials when developed as thin films exhibit better properties compared to nanoparticles. Tin oxide with its outstanding properties such as wide band gap, low electrical resistivity, and good chemical stability is a versatile material in the field of nanomaterials. Metal doped SnO2 in addition exhibits enhanced properties. We report herein the preparation and analysis of the important properties of Al doped and pure SnO2 thin films through a simple sol-gel process and subsequent spin coating on FTO substrates. Microstructural characterization of the thin films was carried out for comparative evaluation of their physical properties. The as-grown thin films were studied using powder XRD technique and the crystallite sizes were estimated for Al doped and bare SnO2 thin films. The surface morphologies of the as-synthesized thin films were examined using High Resolution Scanning Electron Microscope. The observed images indicated lesser agglomeration and good homogeneity in the case of Al doped SnO2 thin films in comparison with its pure counterpart. The surface area, pore volume and pore radius of the samples were determined using BET analysis. The Fourier Transform Infrared Spectroscopy evidenced the presence of the various functional groups related to the materials of the films.

Heterogeneous Photocatalysis: Relationships with Heterogeneous Catalysis and Perspectives

In this paper, the performance of nano-porous electrodes made of a composite material of SrTiO3 and SnO2 are compared with those made of bare SnO2. When these particular devices are analyzed in a comparative mode the results confirmed the enhancement of photovoltaic parameters in the former device. The performance of respective cells were examined by several methods including I−V characteristic measurements, photocurrent action spectra, dark I−V measurements, Mott−Schottky measurements and X-ray diffraction measurements. Even though such improvements in this particular cell could be explicated by the formation of a potential energy barrier of SrTiO3 particles of comparably large width at the SrTiO3/SnO2 interface, the passivation of voids in the SnO2 film by SrTiO3 particles to a certain extent could not be totally ruled out. Besides, high energetic electrons injected by dye molecules move more credibly through mini-bands formed in the chain of nano-crystalline SnO2 particles to the back contact. The blocking of the recombination path and the shifting up of the uppermost electron occupied level of SnO2 accompanying the conduction band edge in the SrTiO3/SnO2 composite film, may have lead to the observed enhancement of the fill factor and photovoltage, respectively.

Efficient Energy Harvesting in SnO2-Based Dye-Sensitized Solar Cells Utilizing Nano-Amassed Mesoporous Zinc Oxide Hollow Microspheres as Synergy Boosters.

Finding the material characteristics satisfying most of the photovoltaic conditions is difficult. In contrast, utilization of foreign materials that can contribute to light harvesting and charge transfers in the devices is now desirable/thought-provoking. Herein, a binary hybrid photoanode utilizing nano-amassed micron-sized mesoporous zinc oxide hollow spheres (meso-ZnO HS) in conjunction with SnO2 nanoparticles (NPs), i.e., SnO2 NP_ZnO HS (for an optimized weight ratio (8:2)), displayed a nearly ∼4-fold increase in the efficiency (η) compared to that of bare SnO2 nanoparticle device. Enhanced device efficacy in the composite photoanode-based device can be accredited to the dual function of nano-amassed meso-ZnO HS. Nano-amassed micron-sized ZnO HS embedded in the photoanode can increase the light-harnessing capability without sacrificing the surface area as well as optical confinement of light by multiple reflections within its cavity and enhanced light-scattering effects. Electrochemical impedance spectroscopy analysis revealed an extended lifetime of electron (τe) and a higher value of Rct2 at the working electrode/dye/redox mediator interface, indicating a minimum photoinduced electron interception. The open-circuit voltage decay reveals a slower recombination kinetics of photogenerated electrons, supporting our claim that the nano-ammased meso-ZnO HS can serve as an energy barrier to the photoinjected electrons to retard the back-transfer to the electrolyte. Moreover, the improvement in the fill factors of the composite-based devices is endorsed to the facile penetration of the electrolyte through the pores of nano-amassed meso-ZnO HS, which increases the regeneration probability of oxidized dyes.

In-situ high loading of SnO2 monocrystals in a tridimensional carbon network via chemical bonding for enhanced lithium storage performance

SnO2 monocrystals with an average particle size of ∼10 nm have been in-situ embedded in a tridimensional carbon network (marked as SnO2@C) with a high loading percentage of 39.5 wt%. The synthetic mechanism of SnO2@C nanocomposite is discussed. The X-ray photoelectron spectroscopies demonstrate probable chemical bonding between SnO2 nanoparticles and the carbon framework for enhanced lithium storage performance of SnO2@C nanocomposite as an anode material for lithium ion batteries. The SnO2@C anode material delivers an initial charge capacity of 844 mAh/g at 0.1 C, and can retain a specific capacity of 661 mAh/g after 700 electrochemical cycles at 1 C (1 C = 0.79 A/g), showing considerably improved cycling and high-rate performance as compared with the bare SnO2 material. The high lithium storage capacity of SnO2@C anode material can be attributed to electrochemical reversibility related to the reduction of SnO to Sn and corresponding re-oxidation process, according to a reversible redox pair at 1.10/1.25 V recorded in CV cycles. The SnO2@C anode also reveals outstanding cycling stability at elevated temperature, resulting in a remaining capacity of 512 mAh/g after 125 cycles at 1 C and 233 mAh/g after 300 cycles at 5 C at 55 °C, respectively. TEM/HRTEM images show desirable structural integrity of cycled SnO2@C nanocomposite and the robustness of the carbon network, which significantly contributes to superior lithium storage performance.

Design of SnO₂ Aggregate/Nanosheet Composite Structures Based on Function-Matching Strategy for Enhanced Dye-Sensitized Solar Cell Performance.

Hierarchical SnO2 nanocrystallites aggregates (NAs) were prepared with a simple room temperature–based aqueous solution method followed by simple freeze-drying treatment. The as-prepared SnO2 NAs were subsequently combined with SnO2 nanosheet–based structures from the viewpoint of a function-matching strategy, and under an optimized condition, a power conversion efficiency (PCE) of 5.59% was obtained for the resultant hybrid photoanode, a remarkable 60% enhancement compared to that of dye-sensitized solar cells (DSCs) fabricated with bare SnO2 NAs architecture. The significantly enhanced efficiency can be attributed to the combination of the desirable electron transport property obtained by the intentionally introduced SnO2 nanosheets (NSs) and the effectively retained inherent characteristics of SnO2 NAs, i.e., large surface area and strong light-scattering effect. This work provides a promising approach for the rapid development of highly efficient SnO2 photoanode film-based DSCs with the properties of simplicity of operation and control over the photoanode composition.

In situ construction of interconnected SnO2/nitrogen-doped Carbon@TiO2 networks for lithium-ion half/full cells

A one-pot in situ pyrrole polymerization strategy, followed by controllable atomic layer deposition of TiO2 and pyrolysis process, is carried out to construct the core-shell SnO2/NC@TiO2 with sub-5 nm SnO2 nanoparticles uniformly dispersing in interconnected nitrogen-doped carbon nanospheres coated by TiO2 layer. Benefiting from the unique structural stability of SnO2/NC@TiO2, as anode materials for LIBs, they show much improved cycling stability and rate capability compared with the bare SnO2 and SnO2/NC electrodes. Specifically, the SnO2/NC@TiO2 electrode with a 10 nm TiO2 coating layer demonstrate the optimal lithium ion storage performance, delivering initial discharge capacity of 1224 mAh g−1 with a first-cycle Columbic efficiency of 72.3% and 871 mAh g−1 after 200 cycles at 100 mA g−1. Moreover, the assembled SnO2/NC@TiO2//LiFePO4 full cell demonstrates a good rate capability with a reversible capacity of 145 mAh g−1 (67% capacity retention of the initial value) when the electrode undergoes various current densities after 70 cycles. The improved electrochemical performance is mainly attributed to the surface interface engineering by the interconnected carbon matrix as well as the uniform TiO2 outer layer. These achieved results suggest that interconnected SnO2/NC@TiO2 electrodes have the potential to be used as anode for high-performance lithium ion battery.

A PdPt decorated SnO -rGO nanohybrid for high-performance resistive sensing of methane

ABSTRACT SnO2, SnO2-PdPt, and PdPt decorated SnO2-rGO (SnO2-rGO-PdPt) samples were presented to use in resistive sensing of methane. A hydrothermal method was used to synthesize SnO2 and SnO2-rGO and these were then easily doped with PdPt catalyst by in situ reductions of their metallic salts. The responses to gaseous methane at levels between 500 and 10,000 ppm were measured in the temperature range of 50–250 °C. Results demonstrated that the dopants can increase the response of SnO2 sensor toward 1000 ppm methane from 12.5% (for bare SnO2) to 32.7% (for SnO2-PdPt) and 69.5% (for SnO2-rGO-PdPt) at 150 °C. In addition, the optimum operating temperature was reduced from 300 °C (for SnO2) to 150 °C (for SnO2-rGO-PdPt). The catalyst also improved the stability during continuous cycles. The response and recovery times of SnO2-rGO-PdPt sensor at 150 °C and flow rate of 160 sccm of 1000 ppm methane, were 50 s and 4.5 min respectively. A sensing mechanism is suggested in details.

Assembly of mesoporous SnO2 spheres and carbon nanotubes network as a high-performance anode for lithium-ion batteries

We report a facile and effective aerosol-spray strategy toward high-performance anodes for lithium-ion batteries by incorporating mesoporous SnO2 spheres of high-capacity materials with surface-modified carbon nanotubes (MCNTs). SnO2 nanocrystals are self-assembled into mesoporous spheres, and MCNTs with abundant carboxylic groups serve as a conductive scaffold. Driven by the strong interaction between the surface of metal oxide and the carboxylic groups on CNTs, a robust nanocomposite architecture is in situ formed. Such nanocomposite architecture possesses several advantages as an anode for lithium-ion batteries. First, mesoporous SnO2 spheres inherit the advantageous features of conventional nanoparticles, such as the capability to accommodate volume expansion and reduce Li+ diffusion distance. Second, the robust interface between nanocrystals in the SnO2 spheres provides the high structural stability that would prolong the life span of the electrode. Third, MCNTs that strongly bind to SnO2 spheres serve as a three-dimensional network, offering both improved electronic transport and mechanical strength of the electrode. Therefore, as-prepared nanocomposite delivers high capacity of 963 mAh g−1 at 0.1 C and 701 mAh g−1 at 5 C, respectively. Significantly improved cycling performance is achieved over the bare SnO2 spheres counterpart.

Development of New CO2 Reduction Catalysts and Construction of Efficient Electro-Reduction Systems

Reduction of CO2 in exhaust gases and its conversion to useful carbon resources are an urgent and important issue to prevent . Carbon positive processes, which consume CO2, are the more effective way to reduce CO2 and to be able to recycle it. We have found that the porphyrin dimers bearing two iron metal centers separated by an appropriate separation as homogeneous catalysts realize CO2 reduction at remarkable high catalytic turnover frequencies (log TOFmax = 5.8), low overpotentials (η > 0.4 V), and high CO selectivity under neutral wet conditions, i.e. without any addition of acidic reagents.[1, 2] According to this highly efficient CO2 reduction, the performance of these dinuclear iron catalysts becomes a bench mark of CO2 reduction catalysts. Such high catalytic activity comes from the CO2 binding to the Fe(II) dimer, though an Fe(II) porphyrin monomer is intact in CO2 atmosphere. The formation of these pre-associated complexes could efficiently promote the succeeding reduction of the bound CO2-to-CO. In order to apply this kind of catalysts to aqueous heterogeneous electro-reduction system, a FTO electrode is modified with Fe porphyrin dimers bearing a phosphonic acid anchor group (Fe2DPPO3H2 ) on its surface.[3] Electrochemical CO2 reduction with the resultant catalyst-modified electrode in a neutral aqueous solution shows CO and H2 formation without any selectivity. Proton reduction could occur on the bare SnO2 surface. The SAM modification of the unmodified FTO surface can successfully block H2 formation by the prevention of the contact of the electrode surface from the solution. However, the low amount of the surface modified catalyst (Γ ≈ 5 x 10-12 mol/cm2) only gave 30-40 μA/cm2 in the electrolysis at -0.95 V vs. NHE (η = 0.42 V) in CO2-saturated 0.1 M KPi solution (pH = 7). In order to increase the surface area of the electrode, meso porous SnO2 layer modification with nano SnO2 particles was applied to a FTO. The resultant 2-μm SnO2 layered electrode co-modified with Fe2DPPO3H2 and SAM was applied to CO2 reduction in 0.1 M KPi and gave 10 times higher current density (i = 1.5 mA/cm2) than that of an ordinary catalyst-modified FTO. The continuous electrolysis for 6 h showed stable current and this proved the electrode is sufficiently stable under these conditions. Since the thickness of the meso porous SnO2 layer on a FTO can be increased up to ≈10 μm, further increase of the current density is possible. In this talk, the latest results of the cell-electrode system involving a non-precious metal anode will be discussed.

Hydrothermal synthesis of CeO 2 SnO 2 nanocomposites with highly enhanced gas sensing performance towards n-butanol

Abstract CeO2 SnO2 nanocomposite, a sensing material, was successfully synthesized by a hydrothermal method. The structural, optical and morphological properties of as-prepared CeO2 SnO2 nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy and field emission scanning electron microscopy (FESEM). The results reveal that the highly crystalline nanocomposite heterostructure is formed, and it possesses a spherical-like morphology with an average grain size of 30 nm. Furthermore, the gas sensing properties towards several volatile organic compounds (VOCs) such as n-butanol, isopropanol, ethanol and acetone were studied. Interestingly, comparing with bare SnO2 and CeO2, the CeO2 SnO2 sensor shows the highest sensitivity towards n-butanol at an operating temperature of 110 °C. This indicates that the CeO2 SnO2 nanocomposite can be a promising candidate for sensor application towards the detection of n-butanol.

One-pot hydrothermal fabrication and enhanced lithium storage capability of SnO2 nanorods intertangled with carbon nanotubes and graphene nanosheets

A three-dimensional (3D) nanoarchitectured ternary composite of SnO2 nanorods intertangled with multiwalled carbon nanotubes and graphene nanosheets (SnO2/CNTs/Gr) was synthesized via one-pot template-free hydrothermal method and investigated as anode for lithium-ion batteries. Compared to bare SnO2 and corresponding binary composites including SnO2/CNTs and SnO2/Gr, SnO2/CNTs/Gr shows significantly improved cycling stability and rate performance. The initial discharge specific capacity of SnO2/CNTs/Gr is 1391 mAh g−1 and remains 522 mAh g−1 after 50 cycles at a current density of 100 mA g−1. Meanwhile, the composite shows excellent rate reversibility. For example, 120 mAh g−1 can be retained at a high current density of up to 1600 mA g−1, and 582 mAh g−1 can still be retrieved once the current density is switched back to 50 mA g−1. The carbon nanotubes and graphene nanosheets in the composites play different enhancing effect. The significantly improved energy storage capability of SnO2/CNTs/Gr can be attributed to a synergistic effect of the intertangled CNTs and graphene nanosheets.

Tin Oxide Nanowires Decorated with Ag Nanoparticles for Visible Light-Enhanced Hydrogen Sensing at Room Temperature: Bridging Conductometric Gas Sensing and Plasmon-Driven Catalysis

We demonstrate that conductometric gas sensing at room temperature with SnO2 nanowires (NWs) is enhanced by visible and supraband gap UV irradiation when and only when the metal oxide NWs are decorated with Ag nanoparticles (NPs) (diameter < 20 nm); no enhancement is observed for the bare SnO2 case. We combine the spectroscopic techniques with conductometric gas sensing to study the wavelength dependency of the sensors’ response, showing a strict correlation between the Ag-loaded SnO2 optical absorption and its gas response as a function of irradiation wavelength. Our results lead to the hypothesis that the enhanced gas response under UV–vis light is the effect of plasmonic hot electrons populating the Ag NPs surface. Finally, we discuss the chemiresistive properties of Ag-loaded SnO2 sensor in parallel with the theory of plasmon-driven catalysis, to propose an interpretative framework that is coherent with the established paradigma of these two separated fields of study.

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

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.

Spray-Drying-Induced Assembly of Skeleton-Structured SnO2/Graphene Composite Spheres as Superior Anode Materials for High-Performance Lithium-Ion Batteries.

Three-dimensional skeleton-structured assemblies of graphene sheets decorated with SnO2 nanocrystals are fabricated via a facile and large-scalable spray-drying-induced assembly process with commercial graphene oxide and SnO2 sol as precursors. The influences of different parameters on the morphology, composition, structure, and electrochemical performances of the skeleton-structured SnO2/graphene composite spheres are studied by XRD, TGA, SEM, TEM, Raman spectroscopy, and N2 adsorption-desorption techniques. Electrochemical properties of the composite spheres as the anode electrode for lithium-ion batteries are evaluated. After 120 cycles under a current density of 100 mA g-1, the skeleton-structured SnO2/graphene spheres still display a specific discharge capacity of 1140 mAh g-1. It is roughly 9.5 times larger than that of bare SnO2 clusters. It could still retain a stable specific capacity of 775 mAh g-1 after 50 cycles under a high current density of 2000 mA g-1, exhibiting extraordinary rate ability. The superconductivity of the graphene skeleton provides the pathway for electron transportation. The large pore volume deduced from the skeleton structure of the SnO2/graphene composite spheres increases the penetration of electrolyte and the diffusion of lithium ions and also significantly enhances the structural integrity by acting as a mechanical buffer.

Synthesis and Catalysis of Mixed Oxides on Mesoporous Mayenite for Biodiesel Production from Castor Oil (Ricinus communis)

Environmental concern has been driving the search for substitutes to the fossil based energy sources and has been pushing forward research for bolstering second generation biodiesel production processes. However, various challenges emerge from the use of such feedstocks, eg. in transesterification processes. The high content of free fatty acids and moisture in the precursor triglycerides are the major restraints for the transesterification reaction. For instance, Ricinus oil can be exploited by the use of a heterogeneous catalyst capable of maintaining high activity. This study shows the development of lithium and tin oxides catalysts supported on mayenite (Ca12Al14O33) for the transesterification of Ricinus oil with methanol (CH3OH). A basic characterization procedure was carried out to establish the quality of the obtained ricinus oil. Once the ricinus oil properties were assessed it was used for the transesterification reaction by catalysts synthesized with mixtures of Li2O, CaO, and SnO2 in different mass ratios. The best performance for the binary mixtures was obtained with 70/30 and 90/10% wt of CaO/SnO2 mass ratios at a temperature of 60°C with a methanol to oil molar ratio of 12:1 and a catalyst load of 5% wt in respect to oil. Furthermore, catalysts with Li2O and SnO2 were synthesized in mass ratios from 50/0 to 0/50% wt on a mesoporous mayenite. The synthesized catalysts were analysed by surface characterization techniques, such as N2-physisorption, NH3-desorption, and scanning electron microscopy (SEM). Furthermore, a central composite design with a response surface methodology was used to optimize the yield. The response surface methodology led to a maximum biodiesel yield of 85% with bare SnO2 on mayenite with 6% wt of a catalyst load in respect to oil, 60°C of a temperature, and 4:1 of a methanol to oil molar ratio. X-ray powder diffraction (XRD) and thermogravimetric analysis (TGA) were used to determine the state of the catalysts after carrying out the aging test of the catalysts in CH3OH.

Facile synthesis of SnO2 hierarchical porous nanosheets from graphene oxide sacrificial scaffolds for high-performance gas sensors

Abstract Facile synthesis of metal oxide semiconductors with controllable and novel nanostructures has attracted tremendous attentions due to their crucial importance in gas detection. In this work, we report the design and synthesis of tin oxide hierarchical porous nanosheets (SnO 2 HPNSs) via a graphene oxide (GO) assisted hydrothermal route, where the GO flakes act as scaffolds and fluoride ions (F − ) act as etchant to control the attachment growth of SnO 2 nanosheets. Highly wrinkled SnO 2 /reduced graphene oxide nanosheets (such as SnO 2 /rGO-5.0 mg) have been achieved with a proper addition amount of GO powders. The wrinkled ultrathin nanosheets are subsequently converted to the SnO 2 HPNSs after annealing at 500 °C in air, which are composed of the network interconnected SnO 2 nanosheets (or nanoparticles). Moreover, the SnO 2 HPNSs based gas sensors exhibit greatly enhanced ethanol sensing performance, with high response (77.1–100 ppm) and good selectivity at an optimum operating temperature of 250 °C, compared with the bare SnO 2 nanosheets (4.0–100 ppm, at 275 °C). A possible gas-sensing enhancement mechanism based on this novel hierarchical architecture is discussed.

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

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 SnO2-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 SnO2 (FTO)-coated glass; (2) cells with an intrinsic SnO2 thin layer on the top of FTO as an effective ESL; and (3) 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 < SnO2-ESL < SnO2 + SAM; this sequence explains the improvements of the fill factor (FF) and open-circuit voltage (Voc). The improvement of the FF from the FTO to SnO2-ESL cells may result from the reduction in voltage loss at the PS/HSL back interface and the improvement of Voc 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 SnO2-based ESL material quality and the ESL/PS interface.

Bilayer SnO2–WO3 nanofilms for enhanced NH3 gas sensing performance

Bilayer SnO2–WO3 nanofilm sensors with high sensitivity and selectivity for NH3 gas were developed. The sensitized WO3 nanofilms (5–15nm) were deposited on the top of SnO2 nanofilms without vacuum break via reactive sputtering. The SnO2 nanofilm sensitized with 10-nm-thick WO3 nanofilm exhibited the best performance for sensing NH3 gas. The gas response (Ra/Rg) value of SnO2–WO3 nanofilm sensor to 250ppm NH3 was as high as 7.1 at 300°C and increased by approximately threefold compared with that of the bare SnO2 nanofilm sensor. At 300°C, the cross-gas responses of the SnO2–WO3 nanofilm sensor to 250ppm H2 (Ra/Rg=1.5) and C2H5OH (Ra/Rg=1.4) were negligibly low. The catalytic effect of WO3 nanofilm on NH3 gas molecules mainly enhanced the NH3-gas-sensing performance of the SnO2 nanofilm sensor. This work proposes an effective platform for the mass-fabrication of miniaturized, cost-effective, and highly sensitive NH3 gas sensors.

Electrospun SnO2/LTO Composite Sub-Micron Dimpled Spheres as High Performance Anode Material for Lithium Ion Batteries

SnO2 is one of the high capacity (782 mAh/g) anode materials used in lithium ion batteries with a tetragonal rutile structure and it alloys at voltage of 0.5V vs Li. However, cyclic stability for SnO2 and Sn based materials is very poor due to high volume expansion during alloying with Li ions (charging) and disintegration of structure during de-alloying (discharging) besides the formation of solid electrolyte interface (SEI) at lower operating voltage of the anode. Many attempts have been made to improve the cycle stability and minimize capacity losses of these materials by nanostructuring, making nanocomposites with graphene and CNT. Even though the results are promising, reproducibility and the scaling up of the electrode material still remains as a challenge. Here we introduce electrospinning as a new way of improving the cycle stability with minimum capacity loss using a composite electrode of SnO2 and lithium titanate (LTO). LTO with a cubic spinel structure can intercalate reversibly with Li ions delivering a capacity of 175 mAh/g, theoretically. Low crystal strains during charging–discharging makes the material work even at high charging rates. The combination of SnO2 and LTO can reduce the volume expansion experienced by bare SnO2 during alloying de-alloying reaction as LTO itself is a zero-strain material.

Low-temperature prototype hydrogen sensors using Pd-decorated SnO2 nanowires for exhaled breath applications

The synthesis and integration of a compact, highly sensitive, and inexpensive gas sensor for breath analysis have attracted considerable attention because of painless application, non-invasiveness, and ability to diagnose diseases during early stages. In this study, we introduced the on-chip growth of SnO2 nanowire (NW)-based gas sensor to analyze the low concentration of H2 gas for exhaled breath applications. We decorated the Pd catalyst on the surface of SnO2 NWs to enhance gas-sensing performance. Comparative results revealed that Pd decoration enhanced the H2 gas response at low operating temperature range (250–300°C). Moreover, the Pd-decorated SnO2 NW sensor exhibited good response to H2 gas at considerably low temperature of 150°C, whereas the bare SnO2 NWs cannot respond. Finally, the packaged sensor was tested at different supplied powers to various H2 concentrations ranging from 10 to 100ppm. Gas selectivity toward CO2 and ethanol gases was examined. Results demonstrated that the prepared gas sensor package is suitable for breath gas analysis.