SnO2 Lattice Research Articles

Influence of metal doping and non-metal loading on photodegradation of methylene blue using SnO2 nanoparticles

Pure SnO2, Zn (0.075 M) doped SnO2 loaded corn cob activated carbon (Zn: SnO2/CCAC) were synthesized by a chemical precipitate process. The influence of Zn doped and CCAC loaded on the crystallite structure, optical, morphology, and photocatalytic properties of pure SnO2 were investigated. The XRD patterns confirmed that Zn doped SnO2 with loaded CCAC sample exhibited a rutile tetragonal structure. The XPS survey confirmed that the Zn ion was incorporated into the SnO2 lattice with a Zn2+ oxidization state. The band gap value of Zn: SnO2/CCAC was reduced (3.48 eV) as compared to pure SnO2 and doped samples. Further, the reduced PL emission intensity of Zn: SnO2/CCAC and its reduced resistance value of impedance from EIS analysis, and the enhanced separation of the photogenerated e−/h+ pairs support the enhanced photodegradation efficiency. The Zn: SnO2/CCAC sample showed improvement in the photodegradation efficiency (98.61 %) of methylene blue (MB) as compared to pure SnO2 and Zn: SnO2, respectively.

Insight into Copper Doping Ratio on Optoelectronics Performance of Two-Dimensional Cu-Doped SnO2 Nanosheets: an Experiment and DFT Study

The optoelectronics performances of two-dimensional Cu-doped SnO2 nanosheets were investigated by first-principles calculations on the basis of density functional theory (DFT) and experiments. First, the crystal structures of Cu-doped SnO2 were built and analyzed by using DFT within the generalized gradient approximation (GGA). The total energy of Cu-doped SnO2 was discussed qualitatively and quantitatively from three aspects: charge density, band structure, and state density. The results show that copper doping has little effect on the charge density distribution because of the similar ionic radius of Cu2+, Sn4+, and the close bond lengths of Cu–O and Sn–O. The calculation results of band structure and state density show that the doping of a copper acceptor leads to the appearance of a new energy level at the top of the valence band and decreases the band gap of SnO2. With the guidance of theoretical calculation, the nanosheets of Cu-doped SnO2 are constructed experimentally, and their optoelectronics performances are investigated. The experimental results exhibit that the Cu atom replaces the Sn atom in the SnO2 lattice, while the Cu-doped SnO2 retains the original rutile phase of the intrinsic SnO2. The sample with a doping ratio of 12.5% has more uniform particle morphology and dispersion characteristics. In addition, the 12.5% Cu-doped SnO2 obtained the largest transient photocurrent of 3 μA/cm2 and the lowest resistance to charge transfer, thereby indicating that the material has a remarkably higher optoelectronics performance under this ratio. The theoretical calculation and experimental results are consistent, which indicates that Cu doping effectively enhances the charge transfer in SnO2 and enables it for high-quality application in optoelectronic catalysis.

Fabrication, structural characteristics, and influence of Bi3+ doping concentration on UV-vis spectra of Bi3+:SnO2 nanocomposite materials

The authors report the characteristics and optical properties of Bi3+-doped SnO2 quantum dots prepared bysol-gel and hydrothermal methods. The structure and morphology of the materials as a function of dopingconcentration were studied and analysed by X-ray diffraction (XRD) and scanning electron microscope(SEM). The structure of the material was assigned to the tetragonal crystal structures of the SnO2 rutile phase,reported in JCPDS Card No. 41-1445. With the increase of Bi3+ doping, the crystallinity of Bi-doped SnO2worsened. The average sizes of the SnO2 nanocrystals were within 3-8 nm. The effect of Bi3+ ion concentrationon the absorbance properties of the materials was investigated by UV-Vis absorption spectra. The absorbancedecreased with increasing the concentration of Bi3+ dopant in the SnO2 lattice. The bandgap width decreasedwith Bi3+ dopant concentration. All Bi3+-doped SnO2 samples presented an enlargement of the light absorptionrange due to a bandgap width decrease.

Gas Sensing Properties of SnO2-Pd Nanoparticles Thick Film by Applying In Situ Synthesis-Loading Method.

In this study, SnO2-Pd nanoparticles(NPs) were made with an in situ synthesis-loading method. The in situ method is to simultaneously load a catalytic element during the procedure to synthesize SnO2 NPs. SnO2-Pd NPs were synthesized by using the in situ method and were heat-treated at 300 °C. As a result, tetragonal structured SnO2-Pd NPs, having an ultrafine size of less than 10 nm and a uniformly distributed Pd catalyst in the SnO2 lattice, were well made and a gas sensitive thick film with a thickness of c.a. 40 μm was well fabricated by using the NPs. Gas sensing characterization for CH4 gas indicated that the gas sensitivity, R3500/R1000, of the thick film consistent with SnO2-Pd NPs synthesized with the in situ synthesis-loading method, followed by heat-treatment at 500 °C, was enhanced to 0.59. Therefore, the in situ synthesis-loading method is available for synthesis of SnO2-Pd NPs for gas sensitive thick film.

Stabilizing Oxidation State of SnO2 for Highly Selective CO2 Electroreduction to Formate at Large Current Densities

Even though electrocatalytic CO2 reduction reaction (CO2RR) to formate has made significant advances, achieving a high cell energy efficiency at industrial-level current densities is still a bottleneck for the large-scale application of this technology. SnO2 is a promising electrocatalyst for formate production but is restricted by the unstable oxidation state under high reduction potentials, causing catalyst reconstruction and inactivation. Herein, we present an atomic doping strategy (by Cu, Bi, or Pt) to trigger the emergence of oxygen vacancy in the SnO2 lattice and stabilize the oxidation state of SnO2 during CO2RR. As a result, the optimal Cu-incorporated SnO2 can keep a high formate Faradic efficiency of >80% and a cell energy efficiency of about 50–60% at a wide range of current densities up to 500 mA cm–2 in a commercial flow cell, surpassing most reported works. A set of in situ spectroscopy measurements and controlled electrochemical tests suggest that the oxygen vacancy, induced by the participation of Cu/Bi/Pt single atoms, holds the key to stabilizing SnO2 as well as promoting the adsorption of formate-related *OCHO reaction intermediate. A qualitative relationship between the oxygen vacancy concentration and CO2-to-formate conversion is constructed on a series of doped SnO2 catalysts.

Role of Sm in tuning the third-order nonlinear optical properties of spray coated Sn1-xSmxO2 films

In this work, the different physical and optical properties of spray coated nanostructured Sn1-xSmxO2 (x = 0.0 to 0.1) films were analyzed using various characterization techniques. All the films exhibited tetragonal structure with (1 1 0) as the prominent plane. The doping in general reduced the crystalline nature of the films along with narrowing of the bandgap values. Among the doped films, the most transmitting film was the 2 at.% Sm doped film, whereas the most crystalline was the 7 at.% Sm doped film. The fibrous morphology changed to distinct grains with the increase in Sm concentration. The oxidation states of the constituent elements were confirmed using X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) intensity was influenced by doping and emissions corresponding to the host SnO2 lattice were observed in the UV and visible regions. The PL emissions corresponding to the Sm ion transitions could not be found in the spectra. All the films exhibited third-order nonlinear optical nature with reverse saturable absorption. The suitability of these films as optical limiting material was identified. The magnitude of third-order nonlinear susceptibility χ(3) was also estimated to be in the range of 10−3-10−2 esu and the least optical limiting threshold was shown by Sn0.93Sm0.07O2 films.

Incorporation of N in p-type Zn-N-doped SnO2 films by varying N2 content in sputtering gas mixture

This study investigates a variation of the N2 content in the mixed sputtering gas effects on the optical, electrical, and structural properties of p-type Zn-N-doped SnO2 films. The incorporation of N into the tin oxide lattice of the synthesized films was confirmed by energy-dispersive X-ray spectroscopy, X-ray diffraction (XRD) analysis, ultraviolet–visible (UV–vis) spectroscopy, and Hall measurements. Further, atomic force microscopy, field-emission scanning electron microscopy, and current-voltage characteristics confirmed the substitution of O by N in the SnO2 lattice. The sufficiently large N3−–O2− substitution in the SnO2 lattice was confirmed by a (200) cubic plane in the XRD pattern. N3−–O2− substitution was also ascertained by the redshift of the UV–vis absorption edge. The crystallinity increased significantly with an increase in N3−–O2− substitution in the SnO2 lattice, including an increase in the crystal grain size and a decrease in surface roughness. The optimum N3−–O2− substitution for the film synthesized using 80% N2 in the mixed sputtering gas resulted in the best crystal quality. This film showed the highest hole mobility and the greatest increase in the photocurrent of the film/n-Si heterojunction. The excess N-substituted O content in the tin oxide lattice degraded the crystal quality. Therefore, the optimally synthesized film is more suitable for optoelectronic devices.

Synthesis and characterization of multi-phase structure, optical and electrical properties on (Ga–Sn) oxide composite thin film by sol-gel method

The structural and optical properties of the films were investigated as a function of increasing high Gallium content amounts in the range 10–30 mol %. The composite thin films were characterized by crystallography, surface morphology, optical and electrical properties. The X-ray diffraction (XRD) method revealed that the composited thin films were multiphase in rutile tetragonal (SnO2) and β phase monoclinic (Ga2O3) type crystal structure with grown strongly in the (200) and (4‾ 01), respectively. In addition, for comparative investigate the effect of high concentration Ga incorporation on the lattice of SnO2 and the mechanism for lattice strain, Williamson-Hall method introduced. The surface morphology was investigated by Field emission Scanning Electron Microscope (FE-SEM) measurement, and it confirmed that crystallite size difference and multi-phase appear with high Ga incorporated. With UV–vis spectrometer, all (Ga–Sn) oxide composite thin films revealed a transparency of approximately 78% in the visible region. For comparative analysis of the band gap of the composite thin film, the estimated value was derived from Tauc plot, and the measured value was investigated by photoluminescence (PL). The electrical sheet resistance was measured by four-point probe method and optimized sheet resistance value of 5.66 kΩ/sq when the mixture of Ga 20 mol % concentration.

High photocatalytic performance of copper-doped SnO2 nanoparticles in degradation of Rhodamine B dye

In this report, co-precipitation approach is used to synthesize pure SnO2 and Cu doped SnO2 nanoparticles (NPs). The crystalline phase, morphological characteristics, chemical contents of the prepared NPs, and photocatalytic capabilities are thoroughly examined. The X-ray diffraction studies depicts that SnO2 has a crystalline, tetragonal structure. In support of XRD, Raman spectroscopy also demonstrates that the successful doping of Cu atoms into SnO2 causes widening and shifting of the peaks. Scanning Electron Microscope (SEM) study shows the surface morphology and agglomeration of pure and Cu doped SnO2 NPs. Energy Dispersive X-ray analysis (EDAX) analysis confirmed the presence of Cu doped in SnO2 lattice whereas, X-ray photoelectron spectroscopy (XPS) reveals the existence of copper (Cu2+) and tin (Sn4+) oxidation states. Absorption and photoluminescence (PL) spectra are analyzed to examine optical characteristics of the prepared samples. Under UV–Visible irradiation, Cu ions with SnO2 NPs degraded Rhodamine B (RhB) dye more efficiently than un-doped samples.

Gas sensors based on Pd-decorated and Sb-doped SnO2 for hydrogen detection

Pd-modified Sb-doped SnO2 nanomaterials were prepared by a simple hydrothermal reaction and reduction method. The as-obtained samples were characterized by X-ray diffraction, scanning electron microscopy, X-ray phosphorescence, and elemental mapping analysis. The extracted results demonstrated even doping of Sb within the SnO2 lattice, and Pd was successfully incorporated on the surface of samples. Compared with the pristine SnO2, 3 mol% Sb doping with 7 wt% Pd decorating exhibited the highest response of 9.7 to 100 ppm H2 at 320 °C and revealed excellent selectivity and cycling stability to hydrogen. The mechanism of the enhanced sensing performance of Pd@Sb-SnO2 can be attributed to the change in the energy band structure by Sb doping, the energy-band bending, and depletion layer generated with the Pd loading. The increased oxygen vacancy caused by the lattice distortion generated by the Sb doping, and the strong metal-support interaction effect between the Pd and SnO2 also plays an important role.

Structure of Atomically Dispersed Pt in a SnO2 Thin Film under Reaction Conditions: Origin of Its High Performance in Micro Electromechanical System Gas Sensor Catalysis.

A battery-driven micro electromechanical system (MEMS) gas sensor has been developed for household safety when using natural gas. The heart of the MEMS gas sensor is a 7.5 at % Pt-SnO2 thin film catalyst deposited on the SnO2 sensor layer. The catalyst enhances the sensitivity to methane, though its structure under working conditions is unclear. In this study, in situ XAFS was applied to a 7.5 at % Pt-SnO2 catalyst layer deposited on a Si substrate, and we demonstrated that atomically dispersed Pt maintains its lattice position in SnO2 with a small loss of surrounding lattice oxygen in the presence of 1% CH4 and a more reducing gas of 1% H2 at the reaction temperature (703 K), i.e., no Pt aggregation is observed. The lost oxygen is easily recovered by re-oxidation by air. This work has revealed that the atomically dispersed Pt in the SnO2 lattice is the active structure and it is stable even under reaction conditions, which guarantees a long lifetime for the gas sensor.

Gadolinium-doped SnO2 electron transfer layer for highly efficient planar perovskite solar cells

Metal halide perovskite solar cells have experienced unexpected rapid growth in the past decade due to their excellent photoelectric conversion efficiency. SnO2 has attracted great attention as a candidate electron transport layer to replace TiO2 in perovskite solar cells. However, the mixture of crystalline and amorphous states produces a large number of oxygen vacancy defects in the SnO2 lattice and surface, leading to nonradiative recombination at the SnO2/perovskite interface. In this work, an effective method of doping the rare earth element Gd in SnO2 is developed for planar perovskite solar cells. Doping with Gd ions can effectively passivate oxygen vacancy defects at the SnO2 interface, leading to a decrease in surface energy, which contributes to facilitating the formation of high-quality perovskite films. Gd doping can also optimize the energy level matching between SnO2 and the perovskite layer, thus improving the charge extraction and transport capabilities. As a result, the optimized device achieves a high power conversion efficiency of 22.40%, with a certified value of 21.95%.

Solvent effect on the optoelectronic properties of fluorine doped SnO2 thin films prepared by spray-pyrolysis

This work explores the effects of choice of solvent on the optoelectronic properties of spray-pyrolyzed fluorine (F)-doped tin oxide (SnO2) thin films deposited on glass substrates over an area of 5 × 5 cm2. A 2-methoxyethanol (C3H8O2) and ethylene glycol (C2H6O2) admixture in varying proportions is used as solvent. The volume of C2H6O2 is varied as 0, 25, 50, and 100 ml in the above admixture. The XRD patterns reveal successful formation of tetragonal SnO2 lattice without any structural change. Upon changing the volume of C2H6O2 in C3H8O2, the textured growth changes from (110) direction to (211) direction. The film thickness is found to vary significantly with varying volume of the mixed solvents. Transmittance is found to increase and reach a maximum value of 75% (at 550 nm) for the film deposited with only C2H6O2. The photoluminescence emission data reveals that the overall intensity of violet emission is found to quench upon increasing the volume of C2H6O2. The sheet resistance is found to decrease gradually with increasing volume of C3H8O2 and is found to be the lowest with a value of 6.34 Ω/□ for complete 100 ml of C3H8O2. The surface wettability nature of the thin films obtained from contact angle measurements indicate changeover from hydrophobic to hydrophilic nature (104.4° to 52.2°) with increasing C2H6O2 vol in the admixed solvent. Among all these samples, the film prepared with 100% C2H6O2 solvent shows highest figure of merit value of 3.02×10–3 Ω–1. The optimal film prepared with complete C2H6O2 solvent has surface work function of 4.69 eV and shows highest power conversion efficiency of 2.21% when used in a dye-sensitized solar cell compared to devices fabricated using other admixed solvents. In the solvent admixture, higher volume of C3H8O2 is beneficial for obtaining low sheet resistance, whereas higher volume of C2H6O2 leads to high transmittance, thereby permitting to fix the solvent concentration based on the need for optical transparency and electrical sheet resistance as per custom requirements for a specific optoelectronic application.

A comparative analysis on electrical and nonlinear optical properties of pure and Co–Ni co-doped SnO2 nanoparticles

Compared to bulk materials, nanostructured materials possess ultrafast optical response and strong two-photon absorption which leads to the utility of materials in various laser related applications. Hence, Cobalt (Co)-Nickel (Ni) co-doped SnO2 nanoparticles were synthesized via co-precipitation technique and its optical limiting behavior was studied. PXRD confirms the formation of tetragonal rutile SnO2with space group P42/mnm with decrease in crystallite size due to co-doping. Shift in PXRD peak position towards higher angle and suppression of Sn–O–Sn vibrational peaks confirm the intervention of Co2+ and Ni2+ ions into the SnO2 lattice. Upon co-doping, the band gap decreases (3.35, 3.28 and 3.20 eV) and the PL intensity of blue-green emission increases due to the increase in density of oxygen vacancies on the surface of SnO2. Low dielectric constant, dielectric loss and ac conductivity indicates the prepared materials are having lesser defects. Nonlinear optical (NLO) absorption and optical limiting behavior of developed NPs were recorded by Z-scan method (open aperture) using nano pulsed green laser excitation. Open aperture Z-scan curves with a valley-like pattern indicate the presence of reverse saturable nonlinear absorption due to the sequential two-photon absorption (2PA) process. The 2PA coefficient increases (0.27–0.56 ×10−10W/m) and onset optical limiting threshold decreases (4.5 –1.7 ×10−12W/m2) with increasing dopant concentration of Co–Ni (2 & 4 wt%) in SnO2 NPs. These results demonstrate that Co–Ni (4 wt%) NPs have virtuous dielectric and efficient NLO absorption and limiting properties which suggest that it could be an eminent candidate for the potential applications such as high-performance dielectric material and optical limiting components in optical devices.

Enhanced Oxygen Vacancies in Ce-Doped SnO2 Nanofibers for Highly Efficient Soot Catalytic Combustion

In this paper, cerium was incorporated into polyhydroxyltriacetictin (PHTES) using the sol-gel method combined with electrospinning technology to prepare a series of composite oxide fiber catalysts SnxCe1−xO2 in different proportions. The structures and soot catalytic activities of SnxCe1−xO2 fibers were studied under loose contact conditions. When Ce entered the crystal lattice of SnO2, the structural symmetry of the SnO2 was destroyed, which inhibited the crystallization and grain growth of the fiber, and fiber catalysts with a larger specific surface area were obtained. Moreover, the introduction of Ce improved the number of oxygen vacancies and redox ability of the catalyst, thus promoting the catalytic activity of the catalyst for soot particles. In particular, among them, the Sn0.7Ce0.3O2 fiber catalysts had the strongest catalytic oxidation ability regarding soot particles and could oxidize soot particles at a lower temperature and faster catalytic rate. The results of the temperature-programmed oxidation of Sn0.7Ce0.3O2 fiber catalyst, conducted three times under the same conditions, were basically consistent, indicating that the experimental results are reliable and repeatable. In addition, the Sn0.7Ce0.3O2 fiber catalyst showed good cycle stability.

Synergistic Effect of Co and Mn Co-Doping on SnO2 Lithium-Ion Anodes

The incorporation of transition metals (TMs) such as Co, Fe, and Mn into SnO2 substantially improves the reversibility of the conversion and the alloying reaction when used as a negative electrode active material in lithium-ion batteries. Moreover, it was shown that the specific benefits of different TM dopants can be combined when introducing more than one dopant into the SnO2 lattice. Herein, a careful characterization of Co and Mn co-doped SnO2 via transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray diffraction including Rietveld refinement is reported. Based on this in-depth investigation of the crystal structure and the distribution of the two TM dopants within the lattice, an ex situ X-ray photoelectron spectroscopy and ex situ X-ray absorption spectroscopy were performed to better understand the de-/lithiation mechanism and the synergistic impact of the Co and Mn co-doping. The results specifically suggest that the antithetical redox behaviour of the two dopants might play a decisive role for the enhanced reversibility of the de-/lithiation reaction.

Role of lithium intercalation in fluorine-doped tin oxide thin films: Ab initio calculations and experiment.

Using a combination of experimental techniques and density functional theory (DFT) calculations, the influence of lithium insertion on the electronic and electrochemical properties of fluorine-doped SnO2 (FTO) is assessed. For this purpose, we investigate the electrochromic behavior of a commercial FTO electrode embedded in a solution of lithium perclorate (LiClO4). The electrochromic properties are evaluated by UV-vis spectroscopy, cyclic voltammetry, and chronoamperometry. These tests show that FTO exhibits electrochromism with a respectable coloration efficiency (η = 47.9 cm2/C at 637nm). DFT study indicates that lithium remains ionized in the lattice, raising the Fermi level about 0.7eV deep into the conduction band. X-ray photoelectron spectroscopy (XPS) is used to study chemical bonding and oxidation states. XPS analysis of the Sn 3d core levels reveals that lithium insertion in FTO induces a shift of 350meV in the Sn 3d states, suggesting that lithium is incorporated into the SnO2 lattice.

Structural, optical and room temperature magnetic properties of sol–gel synthesized (Co, Fe) co-doped SnO2 nanoparticles

Co-Fe co-doped SnO2 nanocrystals with different dopant concentrations (Co = 15 wt% and Fe = 1, 3, 5 wt%) were synthesized by sol–gel technique. XRD spectra revealed the formation of pure SnO2 phase, indicating that the synthesis was effective in diluting the Co and Fe ions into the SnO2 lattice. The structures of the samples were confirmed to be tetragonal, and reductions in lattice parameters confirmed the incorporation of dopant ions in SnO2 lattice. The diffuse reflectance spectroscopy data revealed an increase in the range of absorption and a decrease in energy band gap with an increase in Fe concentration. TEM/SAED confirmed the nanoparticle size and crystalline nature of the samples. The room temperature ferromagnetism was noticed for all the samples, where the magnetization increased with an increase in Fe concentration, whereas the coercivity was more for the sample with less iron concentration. It has been concluded that the ferromagnetic properties depend not only on the distribution of defects but also on the surface diffusion of the dopant ions and nanometric size of the materials.

Effect of Fe Doping on Photocatalytic Dye-Degradation and Antibacterial Activity of SnO2 Nanoparticles

A simple hydrothermal method is utilized to synthesize iron-doped tin oxide nanoparticles (Fe-SnO2 NPs) at various doping concentrations. The structural characterization using XRD, Raman, and FTIR measurements confirmed the incorporation of Fe ions into the SnO2 lattice without any deviation in the tetragonal crystal system of SnO2 nanoparticles. SEM and HRTEM images show the spherical-shaped nanoparticles with agglomeration. The values of interplanar spacing ([Formula: see text]-value) calculated from the HRTEM lattice are consistent with the XRD results. Further, optical analysis revealed a red shift in the optical absorption band and a decrease in the band gap energy with an increase in Fe-dopant concentration. The decrease of PL emission peak intensity with Fe doping revealed the generation of singly charged oxygen vacancies. The H2O2-assisted photocatalytic degradation efficiency of Fe-SnO2 NPs investigated against crystal violet dye indicated an efficiency of 98% for 0.05 M Fe-SnO2 NPs within 30 minutes under visible light illumination. In addition, the effects of pH, scavengers, and reusability of the catalyst are tested. The antibacterial behavior of Fe-SnO2 NPs against Escherichia coli is examined by using the colony count method, and the inhibition rate was found to be 49, 65, 70, and 78% for pure, 0.01, 0.03, and 0.05 M Fe-SnO2 NPs, respectively.

Effect of SnO Composition in SnO/SnO2 Nanocomposites on the Photocatalytic Degradation of Malachite Green under Visible Light

AbstractThree types of SnO/SnO2 nanocomposites with different component ratios were synthesized using a simple hydrothermal process. Three samples, S1, S2, and S3, were produced by optimizing the occupied volume inside the Teflon flask, and are referred to as SnO2 rich, intermediate level, and SnO rich, respectively. In terms of degradation of malachite green under visible light, the photocatalytic activity of the S2 sample outperforms the other two samples and pure SnO by 30 %. It is attributed to the fact that the S2 sample has the most heterojunction between p‐type SnO and n‐type SnO2 of the three samples because the formation of p‐type SnO and n‐type SnO2 heterojunction in S2 prevents photogenerated electron‐hole recombination. By comparing S1 and S3 samples, we figured out that Sn2+ doped into the SnO2 lattice acts as an electron trap, slowing the recombination process and increasing photocatalytic activity.