Pure SnO2 Nanoparticles Research Articles

Ternary SnO2@PANI/rGO nanohybrids as excellent anode materials for lithium-ion batteries

A three-dimensional (3D) nanostructure composed of ternary polyaniline/SnO2/graphene (SnO2@PANI/rGO) nanohybrids were successfully developed and prepared as anode materials for lithium ion batteries (LIBs) by a simple dip-coating of SnO2@polyaniline (SnO2@PANI) and graphene dispersion on Cu foam. In such smart nanostructures, polyaniline (PANI) acts as the conductive matrix as well as a good binding agent of SnO2 nanoparticles and graphene sheets, greatly improving the rate performance to a great extent. The as-prepared ternary nanohybrids exhibit a high reversible specific capacity of 772mAhg−1 at 100mAg−1 with excellent rate capability (268mAhg−1 at 1000mAg−1), more significantly, after 100 cycles at 100mAg−1, our ternary nanohybrids still maintain a high specific capacity of 749mAhg−1, which is much better than SnO2/rGO(458mAhg−1 at 100mAg−1), SnO2@PANI (480mAhg−1 at 100mAg−1) and pure SnO2 nanoparticles (300mAhg−1 at 100mAg−1). Such intriguing electrochemical performance is mainly attributed to the strong synergistic effects among SnO2, polyaniline and graphene. It is reckoned that the present 3D SnO2@PANI/rGO nanohybrids can serve as a promising anode material for LIBs.

Influence of Mn doping on structural, optical and acetone gas sensing properties of SnO2 nanoparticles by a novel microwave technique

In the present work we have successfully synthesized pristine and manganese (Mn) doped SnO2 nanoparticles by using simple microwave irradiation technique for the first time. Powder X-ray diffraction results confirms that both the pure and doped SnO2 in tetragonal rutile type structure. Transmission electron microscopy studies illustrate that both the undoped and Mn doped SnO2 crystallites form in spherical shapes with an average diameter of 35–19 nm, which is in good agreement with the average crystallite sizes calculated by Scherrer’s formula. A considerable red shift in the absorbing band edge was observed with increasing of Mn content (0–10 wt%) by using UV–Vis diffuse reflectance spectroscopy . Oxygen-vacancies, tin interstitial and structural defects were analyzed using photoluminescence spectroscopy. The functional groups were analyzed by using Fourier transform infrared spectra. Acetone gas sensing measurement of pure and Mn-doped (10 wt%) SnO2 nanoparticles were experimented at ambient temperature using optical fiber based on clad modified method. By modifying the clad exposure to acetone vapor, the sensitivities were estimated to be 53 and 78 counts/100 ppm for undoped and Mn-doped SnO2 nanoparticles, respectively. These results show that the Mn doping into SnO2 enhances acetone gas sensing properties.

Highly sensitive acetic acid gas sensor based on coral-like and Y-doped SnO2 nanoparticles prepared by electrospinning

Porous coral-like pure and Y-doped SnO2 nanoparticles were fabricated by electrospinning method and calcination procedure. The porous coral-like SnO2 nanostructure and morphology were characterized by X-ray diffraction (XRD), energy dispersive X-ray detector (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicated that the coral-like structure was composed of SnO2 nanoparticles, and Y-doped SnO2 nanoparticles had smaller particle size of about 6nm. The response of coral-like Y-doped SnO2 based sensor was higher than pure SnO2 for the same acetic acid concentration. These results demonstrate that the coral-like Y-doped SnO2 nanoparticles can be used as the sensing material for fabricating high performance acetic acid sensors. The acetic acid sensing mechanism of SnO2 rectangular nanoparticles was also investigated.

Structural, electrical and magnetic properties of (Fe, Co) co-doped SnO2 diluted magnetic semiconductor nanostructures

Nanostructures (NSs) of basic composition Sn1−xFex/2Cox/2O2 with x=0.00, 0.04, 0.06, 0.08 and 0.1 were synthesized by citrate-gel route and characterized to understand their structural, electrical and magnetic properties. X-ray diffraction and Raman spectroscopy were used to confirm the formation of single phase rutile type tetragonal structure. The crystallite sizes calculated by using Williamson Hall were found to decrease with increasing doping level. In addition to the fundamental Raman peaks of rutile SnO2, the other three weak Raman peaks at about 505, 537 and 688cm−1 were also observed. Field emission scanning electron microscopy studies showed the emergence of structural transformation. Electric properties such as dc electrical resistivity as a function of temperature and ac conductivity as a function of frequency were also studied. The variation of dielectric properties with frequency reveals that the dispersion is due to Maxwell–Wagner type of interfacial polarization in general. Hysteresis loops were clearly observed in M–H curves of Fe and Co co-doped SnO2 NSs. However, pure SnO2 nanoparticles (NPs) showed paramagnetic behaviour which vanished at higher values of magnetic field. The grain and grain boundary contribution in the conduction process is estimated through complex impedance plot fitted with non-linear least square (NLLS) approach which shows that the role of grain boundaries increases rapidly as compared to the grain volume with the increase of Fe and Co ions in to system.

Significantly enhanced dye removal performance of hollow tin oxide nanoparticles via carbon coating in dark environment and study of its mechanism.

Understanding the correlation between physicochemical properties and morphology of nanostructures is a prerequisite for widespread applications of nanomaterials in environmental application areas. Herein, we illustrated that the uniform-sized SnO2@C hollow nanoparticles were large-scale synthesized by a facile hydrothermal method. The size of the core-shell hollow nanoparticles was about 56 nm, and the shell was composed of a solid carbon layer with a thickness of 2 ~ 3 nm. The resulting products were characterized in terms of morphology, composition, and surface property by various analytical techniques. Moreover, the SnO2@C hollow nanoparticles are shown to be effective adsorbents for removing four different dyes from aqueous solutions, which is superior to the pure hollow SnO2 nanoparticles and commercial SnO2. The enhanced mechanism has also been discussed, which can be attributed to the high specific surface areas after carbon coating.

Correlated room temperature ferromagnetism and photoluminescence in Al-doped SnO2 nanoparticles

The correlated room temperature ferromagnetism and photoluminescence were investigated in Al-doped SnO2 nanoparticles (about 50 nm) synthesized by the sol-gel method. X-ray diffraction and selected area electron diffraction results show that the Sn1−x Al x O2 samples possess typical rutile structure and have no other impurity phases with Al fractions of up to 8 at.%. The optical bandgap energies decrease, while the Urbach energies increase with Al concentration. The ferromagnetic signature was found to be significantly enhanced after Al doping, with the saturation magnetization reaching a maximum of 7.3 × 10−3 emu/g in Sn0.92Al0.08O2 sample. The photoluminescence studies clearly indicated the presence of a large concentration of singly ionized oxygen vacancies in the pure and Al-doped SnO2 nanoparticles. An interesting correlation between the saturation magnetization and green–yellow luminescence intensity with the increase of Al doping has suggested that the observed ferromagnetic ordering of the Sn1−x Al x O2 nanoparticles is related to the singly ionized oxygen vacancies.

Dye-sensitized solar cells based on tin dioxide nanoparticles prepared by a facile hydrothermal method

Pure SnO2 nanoparticles with tetragonal structure were successfully synthesized by using a hydrothermal method and then were employed as a photoanode in dye-sensitized solar cells (DSSCs). A Schiff base ligand was applied to prepare uniform SnO2 nanoparticles. The morphology and crystalline size of nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectrum, Electron Dispersive X-ray spectroscopy (EDX) and ultraviolet–visible (UV–vis) spectroscopy. The optical band gap of the SnO2 nanoparticles was estimated to be 3.8eV. The photovoltaic properties of SnO2 electrodes have been investigated and it is shown that using uniform SnO2 nanoparticles as an active electrode is more beneficial than agglomerated nanoparticles.

Two-solvent method synthesis of SnO2 nanoparticles embedded in SBA-15: Gas-sensing and photocatalytic properties study

Different loadings of SnO2 nanoparticles embedded in mesoporous silica (SBA-15) were prepared via a two-solvent method with the ordered hexagonal mesoporous structure of SBA-15 kept. X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy and N2 adsorption porosimetry were employed to characterize the nanocomposites. Compared with pure SnO2 nanoparticles, the SnO2/SBA-15 nanocomposites show higher response to H2 at lower operating temperature. The photocatalytic activity of as-prepared SnO2/SBA-15 for degradation of methylene blue was investigated under UV light irradiation and the results show that the SnO2/SBA-15 nanocomposites have higher photodegradation ability toward methylene blue than pure SnO2 nanoparticles.

Highly loaded SnO2/mesoporous carbon nanohybrid with well-improved lithium storage capability

This paper reports the synthesis of highly loaded SnO2/mesoporous carbon (MC) nanohybrid through a facile chemical solution process and subsequent annealing methodology, by using a novel three-dimensional (3D) MC as a buffering and conducting matrix. Owing to its unique structural characteristics, the MC–SnO2 nanohybrid anode exhibits markedly improved cycling stability and rate capability compared to pure SnO2 nanoparticles, facilitating its application in advanced Li-ion batteries (LIBs) with long cycle life and high power density.

Development of high sensitivity ethanol gas sensor based on Co-doped SnO2 nanoparticles by microwave irradiation technique

We have successfully synthesized Co doped SnO2 nanoparticles by a simple microwave irradiation technique. Powder X-ray diffraction results reveal that the SnO2 doped with cobalt concentration from 0 to 5 wt % crystallizes in tetragonal rutile-type structure. The products were annealed at 600 °C for 5 h in ambient atmosphere in order to improve crystallinity and structural perfection. Transmission electron microscopy (TEM) studies illustrate that both the undoped and Co doped SnO2 crystallites form in spherical shapes with an average diameter of 30–15 nm, which is in good agreement with the average crystallite sizes calculated by Scherrer's formula. A considerable red shift in the absorbing band edge was observed with increasing of Co content (0–5 wt %) by using UV–Vis diffuse reflectance spectroscopy (DRS). Oxygen-vacancies, tin interstitial and structural defects were analyzed using photoluminescence (PL) spectroscopy. Electron paramagnetic resonance (EPR) spectroscopic studies clearly showed that the Co2+ was incorporated into the SnO2 host lattice. Ethanol gas sensitivity of pure and Co-doped (5 wt %) SnO2 nanoparticles were experimented at ambient temperature using optical fiber based on clad-modified method. By modifying the clad exposure to ethanol vapor, the sensitivities were estimated to be 18 and 30 counts/100 ppm for undoped and Co-doped SnO2 nanoparticles, respectively. These results show that the Co doping into SnO2 enhances its ethanol gas sensitivity significantly.

Sol–gel synthesis of SnO2–MgO nanoparticles and their photocatalytic activity towards methylene blue degradation

SnO2–MgO mixed metal oxide nanoparticles were prepared by a simple sol–gel method. The nanoparticles were characterized by power X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The XRD results indicate the formation of mixed metal oxide nanoparticles and also a decrease of SnO2 crystallite size in the mixed metal oxide nanoparticles with increasing magnesium oxide content. The reflectance spectroscopy results show a blue shift of the band gap of SnO2 in the mixed metal oxide nanoparticles. The photocatalytic activity of the SnO2–MgO nanoparticles was tested using the photodegradation of aqueous methylene blue in the presence of sunlight. The results indicate that the mixed metal oxide nanoparticles possess higher efficiency for the photodegradation of methylene blue compared to pure SnO2 nanoparticles.

Preferred orientation growth and size tuning of colloidal SnO2 nanocrystals through Gd3+ doping

Colloidal SnO2 nanocrystals are prepared via a solvothermal method using oleic acid as a stabilizing agent. Preferred orientation growth along [001] direction of colloidal SnO2 nanocrystals is observed, thereby pure SnO2 nanoparticles with quasi-sphere shape being converted to nanorods due to Gd3+ ions doping. In addition, with increasing Gd3+ doping concentration, the size of SnO2 nanorods decreases. The decrease in size and the change in the shape are ascribed to the increase in the growth rate along [001] direction due to the cationic doping with a surface charge modification. Our results demonstrate a simple method to tune the size and shape of SnO2 nanocrystals through cationic doping with Gd3+ ions.

In situ Au-catalyzed fabrication of branch-type SnO2 nanowires by a continuous gas-phase route for dye-sensitized solar cells

Branch-type SnO2 nanowires with high crystallinity have been successfully prepared by a rapid and continuous flame spray pyrolysis (FSP) route. The SnO2 branch has an average diameter of 15–20 nm and a length of 200–700 nm. As is known, this is the first time one dimensional SnO2 nanowires with branch-type nanostructures have been synthesized using flame synthesis. The average growth rate of nanowires could reach 1 μm s−1, which is thousand times faster than other methods. Interestingly, it is found that Au nanoclusters appear at the tip of SnO2 nanowires. An in situ Au-catalyzed vapour–liquid–solid (VLS) model is proposed to explain the growth mechanism of branch-type SnO2 nanowires in flame. As photoanodes, the DSSCs based on branch-type SnO2 nanowires (with TiCl4 post-treatment) show a higher short-circuit current (JSC = 10.60 mA cm−2) and a superior power conversion efficiency of 4.23%, improved by 99.5% compared to pure SnO2 nanoparticles (2.12%). The efficiency improvement could be attributed to the unique branch-type nanowire architecture, which provides a highly efficient electron channel and excellent ability of light scattering.

Reduced Graphene Oxide Mediated SnO2 Nanocrystals for Enhanced Gas-sensing Properties

SnO2–reduced graphene oxide (SnO2–rGO) composites were prepared via a hydro–thermal reaction of graphene oxide (GO) and SnCl2∙2H2O in the mixed solvent of ethylene glycol and water. During the redox reaction, GO was reduced to rGO while Sn2+ was oxidized to SnO2, uniformly depositing on the surface of rGO sheets. The composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), infrared spectra analysis (IR) and transmission electron microscopy (TEM), respectively, and their gas sensing properties were further investigated. Compared with pure SnO2 nanoparticles, the as-prepared SnO2–rGO gas sensor showed much better gas sensing behavior in sensitivity and response–recovery time to ethanol and H2S at low concentrations. Overall, the highly sensitive, quick-responding and low cost SnO2–rGO gas sensor could be potentially applied in environmental monitoring area.

Flexible Free-Standing Graphene/SnO2 Nanocomposites Paper for Li-Ion Battery

A flexible free-standing graphene/SnO₂ nanocomposites paper (GSP) was prepared by coupling a simple filtration method and a thermal reduction together for the first time. Compared with the pure SnO₂ nanoparticles, the GSP exhibited a better cycling stability, because the graphene with high mechanical strength and elasticity can work as a buffer to prevent the volume expansion and contraction of SnO₂ nanoparticles during the Li⁺ insertion/extraction process. Meanwhile, compared with single graphene paper, the GSP showed a higher capacity because of the hybridizing with higher capacity SnO₂ nanoparticles. The excellent electrochemical performance of the GSP as an anode material in Li-ion battery was obtained. The as-prepared GSP shows a great potential for flexible Li-ion batteries.

Variation of structural, optical and magnetic properties with Co-doping in Sn1−xCoxO2 nanoparticles

Pure and Co-doped SnO2 nanoparticles with various Co concentrations of 1%, 3%, 5%, 7% and 10% have been synthesized by the coprecipitation technique. X-ray diffraction and field emission scanning electron microscope equipped with energy dispersive spectrometer were performed to analyze the crystal structure and check the possible presence of any impurity elements in the nanocrystals. Optical absorption and photoluminescence spectra were used to confirm that the Co is substituted at the Sn site in SnO2 matrix and does not form metallic clusters and other oxide phases for Sn1−xCoxO2 (x=0.00–0.10). Meanwhile, it was revealed that the energy band gap decreases and emission peak blue-shifts with the increasing Co-doping. Magnetization measurement shows that the low Co-doping (x≤0.03) develops the ferromagnetism and paramagnetism, but they are weakened by the higher Co-doping due to the formation of antiferromagnetic superexchange coupling among neighboring Co ions. The observed magnetic behaviors support the bound magnetic polarons model.

Structural Stability and Performance of Noble Metal-Free SnO2-Based Gas Sensors.

The structural stability of pure SnO2 nanoparticles and highly sensitive SnO2-SiO2 nanocomposites (0–15 SiO2 wt%) has been investigated for conditions relevant to their utilization as chemoresistive gas sensors. Thermal stabilization by SiO2 co-synthesis has been investigated at up to 600 °C determining regimes of crystal size stability as a function of SiO2-content. For operation up to 400 °C, thermally stable crystal sizes of ca. 24 and 11 nm were identified for SnO2 nanoparticles and 1.4 wt% SnO2-SiO2 nanocomposites, respectively. The effect of crystal growth during operation (TO = 320 °C) on the sensor response to ethanol has been reported, revealing possible long-term destabilization mechanisms. In particular, crystal growth and sintering-neck formation were discussed with respect to their potential to change the sensor response and calibration. Furthermore, the effect of SiO2 cosynthesis on the cross-sensitivity to humidity of these noble metal-free SnO2-based gas sensors was assessed.

Room temperature trace level detection of NO2 gas using SnO2 modified carbon nanotubes based sensor

A hybrid SnO2 modified multiwalled carbon nanotubes (MWCNTs) gas sensor is developed for the trace level (100 ppb) detection of NO2 gas at room temperature. A simple method is applied for the synthesis of a hybrid sensor; SnO2-modified multiwalled carbon nanotubes (MWCNTs), in which MWCNT bundles are uniformly coated in situ with SnO2 nanoparticles (∼4 nm). The concentration of MWCNTs has been varied and the hybrid MWCNT–SnO2 sensor prepared using an optimum content of MWCNT (5 mg) is found to exhibit enhanced sensing response characteristics (response = 5.5 × 103) towards 100 ppb NO2 gas at a low operating temperature of 50 °C, with comparatively faster response and recovery speeds of 2.3 min and 6.8 min, respectively, as compared to sensor structure based structures based on thin films of pure SnO2 nanoparticles (response = 1.01 × 102). The hybrid sensor also exhibits a good response (1.07 × 103) to 100 ppb NO2 gas at room temperature. Extensive modulation of the space charge regions formed at the interface of n-type semiconducting nanoparticles of SnO2 with p-type MWCNTs with interaction to the NO2 gas along with providing the conducting channels by CNTs for charge carriers are responsible for the enhanced response characteristics of the hybrid sensor.

Preparation and Characterization of Cerium-Doped Tin Oxide Gas Sensors

In this paper, the precursors were synthesized by microwave hydrothermal method using SnCl4•5H2O and Ce(NO3)3·6H2O as raw material, CO(NH2)2 as precipitants, respectively. Pure SnO2 nanoparticles and cerium-doped SnO2 nanoparticles were obtained. Furthermore, five kinds of SnO2 thick film gas sensors were fabricated from the above SnO2 nanoparticles (the sensors denoted as sensor SC0, SC2, SC3, SC4 and SC6, respectively). The experiment results showed that, compared with pure SnO2 thick film gas sensor, the intrinsic resistance of cerium-doped SnO2 thick film gas sensors decreased, and their sensor responses to acetone vapor increased, which are discussed in relation to the SEM micrographs of thick film sensors.

Effect of Mn-Doping on Structural, Optical, and Dielectric Properties of SnO2 Nanoparticles by Coprecipitation Method

Pure and Mn-doped SnO2 nanoparticles are prepared by co-precipitation method. The structural analysis reveals the presence of tetragonal system of SnO2. Fourier transform infrared spectroscopy (FTIR) spectra of pure SnO2 show the occurrence of O-Sn-O vibrational mode at around 671 cm−1. It is observed that the wavenumber is shifted to lower region with the increase in Mn dopant concentration. As the Mn content is increased, a clear indication of red shift is observed in the UV-vis absorption spectra. From the scanning electron microscope (SEM) image, the surface morphology of the sample shows uniformly dispersed particles, which are spherical in shape. From dielectric studies, the dielectric constant suddenly drops to 0.5 × 106 Hz, and thereafter, it shows a constant behavior. Dielectric loss plot of the prepared samples exhibits a linear behavior at higher frequency region, which suggests the samples possess a lossless nature. The ac conductivity value drops linearly with the increase in dopant level. This is due to the particle size effect and screening effect caused by the impurities.