SnO2 Nanostructures Research Articles

Environmentally sustainable synthesis of SnO2 nanostructures for efficient photodegradation of industrial dyes

Environmentally sustainable synthesis of SnO2 nanostructures for efficient photodegradation of industrial dyes

Natural sunlight driven photocatalytic dye degradation by biogenically synthesized tin oxide (SnO2) nanostructures using Tinospora crispa stem extract and its anticancer and antibacterial applications.

In the present study, tin oxide (SnO2) was synthesized by advocating the principles of green chemistry for the photo-mediated degradation of pollutants, antimicrobial, and as an antitumor agent. Bioactive SnO2 (nanorods & nanospheres) were fabricated using Tinospora crispa stem extract (TCSE) via sol-gel technique and characterized extensively. XRD, UV-VIS, FTIR, and XPS studies confirmed the formation of crystalline and well stoichiometric pure phase of SnO2 nanostructures with optical bandgap 3.2 to 3.5eV. The transmission electron microscopy (TEM) results demonstrated the effect of secondary phytoconstituents on the shape of SnO2 in a concentration dependent manner. The morphological variations in the obtained nanostructures attributed to the nucleation density and coalescence effect leading to the formation of nanorods with an average diameter 23-25nm whereas the average particle size of the nanospheres obtained was found to be 23-30nm. The zeta potential value of SnO2 nanorods was high (- 58.9mV) indicating the higher stability compared to nanospheres (- 15.6mV). The SnO2 nanostructures were investigated for the simultaneous degradation of methylene blue with degradation efficiency of 92.3% and 47.3% for rhodamine B in mono system and 72.3%, 47.7% respectively for binary dye system. The anticancer activity of SnO2 nanorods explored against human breast cancer (MCF-7) cells revealed a concentration dependent cytotoxic effect reactive oxygen species (ROS) induced cell death. Additionally, efficient antibacterial activity of SnO2 was established using E.coli. Multifaceted applications of Tinospora crispa stem extract mediated SnO2 nanostructures.

A comparative study on the structural and spectroscopic ellipsometry characterizations of (Co, Ni)-doped SnO2 nanostructured films spin-coated on glass substrates

A comparative study on the structural and spectroscopic ellipsometry characterizations of (Co, Ni)-doped SnO2 nanostructured films spin-coated on glass substrates

Insight into the adsorption, photocatalytic and magnetic properties of bandgap tailored hydrothermally grown SnO2:Ni/Cu nanostructures

Application of pristine and (2.5–5) wt% Ni, Cu doped SnO2 as adsorbent for the removal of Malachite green (MG) dye under natural solar light has been investigated in the present study. Synthesized nanostructures are characterised by XRD, XPS, BET, FESEM and UV–Visible spectroscopy. Sorption data were examined using Lagergren's pseudo first order, second order and intra particle diffusion kinetic models. Pseudo second order kinetic model was found suitable for describing the adsorption mechanism in this study. The calculated thermodynamic parameters revealed the endothermic, spontaneous and thermodynamically feasible nature of sorption mechanism of MG dye onto pristine and doped SnO2 nanostructures. Compared with other samples, 5% Cu doped SnO2 showed better photocatalytic degradation efficiency by removing 81.42% percentage of initial dye concentration within 240 min of contact time. SQUID measurement gave an account on the existence of ferromagnetic behaviour for Ni and Cu doped SnO2 nanostructures.

Green Synthesis of NiO-SnO2 Nanocomposite and Effect of Calcination Temperature on Its Physicochemical Properties: Impact on the Photocatalytic Degradation of Methyl Orange

Background: Nickel stannate nanocomposites could be useful for removing organic and toxic water pollutants, such as methyl orange (MO). Aim: The synthesis of a nickel oxide-tin oxide nanocomposite (NiO-SnO2 NC) via a facile and economically viable approach using a leaf extract from Ficus elastica for the photocatalytic degradation of MO. Methods: The phase composition, crystallinity, and purity were examined by X-ray diffraction (XRD). The particles' morphology was studied using scanning electron microscopy (SEM). The elemental analysis and colored mapping were carried out via energy dispersive X-ray (EDX). The functional groups were identified by Fourier transform infrared spectroscopy (FTIR). UV-visible diffuse reflectance spectroscopy (UV-vis DRS) was used to study the optical properties such as the absorption edges and energy band gap, an important feature of semiconductors to determine photocatalytic applications. The photocatalytic activity of the NiO-SnO2 NC was evaluated by monitoring the degradation of MO in aqueous solution under irradiation with full light spectrum. The effects of calcination temperature, pH, initial MO concentration, and catalyst dose were all assessed to understand and optimize the physicochemical and photocatalytic properties of NiO-SnO2 NC. Results: NiO-SnO2 NC was successfully synthesized via a biological route using F. elastica leaf extract. XRD showed rhombohedral NiO and tetragonal SnO2 nanostructures and the amorphous nature of NiO-SnO2 NC. Its degree of crystallinity, crystallite size, and stability increased with increased calcination temperature. SEM depicted significant morphological changes with elevating calcination temperatures, which are attributed to the phase conversion from amorphous to crystalline. The elemental analysis and colored mapping show the formation of highly pure NiO-SnO2 NC. FTIR revealed a decrease in OH, and the ratio of oxygen vacancies at the surface of the NC can be explained by a loss of its hydrophilicity at increased temperatures. All the NC samples displayed significant absorption in the visible region, and a blue shift is seen and the energy band gap decreases when increasing the calcination temperatures due to the dehydration and formation of compacted large particles. NiO-SnO2 NC degrades MO, and the photocatalytic performance decreased with increasing calcination temperature due to an increase in the crystallite size of the NC. The optimal conditions for the efficient NC-mediated photocatalysis of MO are 100 °C, 20 mg catalyst, 50 ppm MO, and pH 6. Conclusions: The auspicious performance of the NiO-SnO2 NCs may open a new avenue for the development of semiconducting p-n heterojunction catalysts as promising structures for removing undesirable organic pollutants from the environment.

Enhancing the thermoelectric power factor of nanostructured SnO2 via Bi substitution

Tin dioxide (SnO2) has recently proved to be a promising material for thermoelectric applications. We have investigated the influence of highly valence Bi doping as an electron donor in oxygenated SnO2 materials on their thermoelectric properties. We have synthesized the pure and Bi doped SnO2 nanoparticles (x = 0%, 5%, 10%, and 15%) through a simple hydrothermal approach. The Seebeck coefficient and Hall measurements have been used to determine thermoelectric behaviour. The measured value of the Seebeck coefficient increases from - 56 to - 83 μV/°C as the Bi content increases. This improvement in the Seebeck coefficient has been attributed to the charge carrier localization (energy filtering effect) caused by the inclusion of the bismuth atoms and the presence of secondary phases based on BiO2. However, the electrical conductivity measurements show an inverse relation with the Bi doping, increasing the impurities. The Sn1-xBixO2 sample with x = 15 has achieved the maximum Seebeck value, resulting in the upward trend in power factor of up to 1.97 × 10−4 Wm−1C−2. Further, we have used X-ray diffraction and scanning electron microscopy to determine the effect of Bi on the SnO2 crystal structure and surface morphology. Which also demonstrates the presence of composites with mixed phases.

Morphological and structural study on low cost SnO2 counter electrode and its applications in quantum dot sensitized solar cells with polysulfide electrolyte

Fabrication of efficient CdS quantum dot sensitized solar cell with a novel stable counter electrode based on a thin film of SnO2 is revealed. The film was characterized by using Scanning Electron Microscopy (SEM), High-Resolution Tunneling Microscopy, X-ray diffraction (XRD) and UV–Visible spectroscopic techniques. Photovoltaic performances and Electrochemical Impedance Spectroscopic techniques (EIS) were performed on FTO/TiO2/CdS/polysulfide/SnO2/FTO device under the light illumination of 100 mW cm−2 and comparison was done with the conventional Pt counter electrode. Impressive 43 % efficiency enhancement in these solar cells was achieved compared with the Pt based devices. Porous thick nanostructure of SnO2 with crystal defects such as oxygen vacancies and Sn vacancies arising from lattice structures as confirmed by SEM, Raman and, XRD spectroscopy could be some of the reasons for this enhancement. Excellent photo enhanced electrocatalytic activity against the polysulfide electrolyte is confirmed by EIS and Cyclic Voltammetry studies.

Production of biodiesel from waste cooking oil using mesoporous MgO-SnO2 nanocomposite

Mesoporous, bifunctional MgO-SnO2 nanocatalysts with enhanced surface area are used for producing biodiesel from waste cooking oil. Biodiesel with yield of 80% is achieved within the first 20 min when transesterification is carried out at an optimum condition of 18:1 methanol to oil ratio, 2 wt% of nanocatalyst, and at a reaction temperature of 60 °C. The conversion gives a maximum yield of 88% when transesterification is allowed to continue for 120 min. The waste cooking oil used in this work is dominated with linoleic acid and oleic acid, which during transesterification gets converted into methyl linoleate and 9-octadecenoic acid methyl ester. These nanocatalysts are fabricated using a composite of rutile (tetragonal) phase SnO2 and cubic phase MgO nanostructures with prominent crystal orientation along [211] and [200] plane respectively. The MgO-SnO2 nanocomposites with an enhanced surface area of 31 m2/g, basic sites of 2 mmol/g, and particle size of ~15 nm are synthesized by novel sequential thermal decomposition and sol-gel technique. The synthesized wide band gap nanocomposites have Mg and Sn in the ratio of 15:1 and do not have any impurity phases as observed in the X-ray diffraction pattern and EDS spectrum. The presence of surface oxygen states and Mg2+ and Sn4+ oxidative states is responsible for the catalytic activity and recyclability displayed by the composites. This work signifies the role of nanocomposites and their synthesis conditions in improving the rate of transesterification. These metal oxide nanocomposites which are nontoxic, stable, cost effective, and easier to synthesis are promising catalysts for large-scale transesterification of waste cooking oil to biodiesel.

Preparation and Physicochemical Properties of Nanomaterial/Fullerene Composites

Bismuthene, an exfoliated two-dimensional material obtained from bulk bismuth, has drawn significant attention because of its unique electronic properties. Few-layered bismuthene (FLBi) with an average thickness of 1.0 nm was synthesized by the ball mill and sonication method. The FLBi film was fabricated onto a semiconducting SnO2 electrode by electrophoretic deposition (SnO2/FLBi). In the flash-photolysis time-resolved microwave conductivity measurement, the SnO2/FLBi film showed a rise of conductivity upon photoexcitation, supporting the occurrence of the electron injection from the photoexcited FLBi to the conduction band of SnO2. The SnO2/FLBi on a transparent fluorine-doped tin oxide (FTO) electrode was used for photoelectrochemical devices. Photocurrents produced by the FTO/SnO2/FLBi electrode were larger than those produced by the FTO/SnO2 and FTO/FLBi electrodes because of the efficient electron injection. Moreover, FLBi was noncovalently functionalized with fullerene C60 in a mixed solvent of toluene and acetonitrile. Upon photoexcitation, the composite of FLBi and C60 exclusively led to the occurrence of photoinduced energy transfer from C60 to FLBi without generating the charge-separated state. These results give fundamental insights into the feasibility toward the construction of FLBi-based optoelectronic devices.Supramolecular composites consisting of fullerene C60 and carbon nanodiamond (ND) were prepared through spontaneous complexation of C60 aggregates onto the surface of ND aggregates in N-methylpyrrolidone. The resultant C60-ND composite was fabricated onto a nanostructured SnO2 electrode by an electrophoretic deposition method. Formation of the C60-ND composite was supported by dynamic light scattering and field-emission scanning electron microscopy. The C60-ND composite on the SnO2 electrode revealed high incident photon-to-current efficiencies in the visible region in comparison with the single component system of C60 or ND. The enhanced photocurrent generation of the C60-ND composite may originate from the photoinduced charge separation at the interface between C60 and ND. These results will give important insight into the design of all-nanocarbon optoelectronic devices.[1] T. Umeyama, Y. Okawada, T. Ohara, and H. Imahori, Chem. Asian J., 14, 4042-4047 (2019).[2] T. Umeyama, H. Xu, T. Ohara, Y. Tsutsui, S. Seki, H. Imahori, J. Phys. Chem. C, 125, 13954-13962 (2021).

Pd nanoparticle-mediated acetone sensing performance improvement of SnO2 substrate: A combined DFT and experimental study

The article presents a combined theoretical and experimental study attempting to show how Pd nanoparticles (NPs) loading onto SnO2 substrate improves the acetone gas sensing performance. Pristine nanostructured SnO2 and Pd nanoparticles (Pd NPs) loaded SnO2 substrates have been prepared, characterized, and their acetone sensing performances have been measured. Experimental measurements have shown that Pd NP loading onto SnO2 suppresses the interfering effects of ethanol, water vapors, etc., and enhances the acetone sensor response, reversibility, response/recovery speeds, and signal-to-noise ratio. Various parameters like the adsorption energy, HOMO–LUMO energy gap, charge distribution, polarizability change, electrophilicity index, global hardness, etc., of several model systems, have been computed by using DFT. The computed parameters have been correlated with the conductivity, local reactivity, sensor response and selectivity, response/recovery times, etc., of the systems to understand the molecular-level effects of the Pd NP loading onto the SnO2 on the gas sensing process.

Structural properties of ordered porous SnO2 nanostructure

Three-dimensional porous ordered SnO2 nanostructures have been fabricated by templating a sol–gel pre- cursor solution against the polystyrene nanospheres for the first time. Field emission scanning electron micrography (FESEM) indicates that the surface of the nanostructures is highly regular and the porous structures are perfectly ordered. Besides a broad emission band at 600 nm, the porous SnO2 nanostructures show an additional emission band at 430 nm, which is seldom seen in the bulk SnO2 materials. Spectral examinations and analyses reveal that the 430 nm band is induced by the interfacial effects between the porous frameworks.

Facile route to prepare hybrid TiO2-SnO2 DSSCs

Using a hybrid sol–gel and electrospinning method, one-dimensional SnO2 nanostructures were fabricated with average diameters of 86 and 53 nm after calcination at 500 and 600 °C, respectively. The morphology and structure of the obtained materials were analyzed using transmission and scanning electron microscopy (TEM, SEM) and X-ray diffraction (XRD). Additionally, the chemical composition was confirmed using Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. Based on BET and BJH analysis, the specific surface area and porosity of SnO2 nanowires were evaluated. The optical properties of the prepared materials were investigated by UV–Vis spectrophotometer. The analyses confirmed that polycrystalline SnO2 nanostructures composed of two polymorphic varieties tetragonal and rhombohedral were derived, whose calcination temperature had a significant effect on the diameter, specific surface area and energy gap width. The fabricated nanowires were added at 5 and 10 mg to P25 TiO2 paste and screen-printed onto FTO substrate. After drying and calcination, the TiO2 NPs-SnO2 NWs hybrid photoanode was charged with dye, electrolyte and platinum electrode were applied and its performance was investigated in a dye-sensitized solar cell (DSSC). The study showed that the addition of 5 mg SnO2 increased the cell efficiency by 12% compared to the standard P25. The results presented in this study are a good base for further research and shows how important it is to work on the application of nanomaterials produced by the electrospinning technique, which will help to develop and increase the efficiency and competitiveness of DSSC.

The effect of rGO and chemical reduction under hydrazine on the structural, electrical and optical properties of nanostructured SnO2:F/rGO thin films

In this study, SnO2:F-rGO thin films were prepared by spray pyrolysis method on glass substrates. The effect of rGO and chemical reduction with Hydrazine on the structural, electrical, and optical properties of FTO:rGO thin films has been investigated. To deposition FTO: rGO thin films, different atomic ratios of fluorine to tin were changed as [F/Sn] = 0, 0.25, 0.5, 0.7 and 1 with a constant value of reduced graphene oxide (rGO). The X-ray diffraction study showed that all FTO: rGO thin films have a polycrystalline structure with tetragonal crystal structure and were preferably oriented in (200) direction. FE-SEM images showed that hydrazine as a reduction agent increased grain size and decreased porosity of FTO: rGO samples. The results of electrical measurements of thin films showed that the minimum sheet resistance equal to 118 Ω/□ was obtained for FTO: rGO with [F/Sn] = 0.5 thin films. The Hall Effect test showed the conductivity of all samples to be n-type and the carrier concentration was obtained from the order of 1021 cm−3. Also, the values of dislocation density and, micro-strain of FTO: rGO thin films were calculated. Finally, the results of UV–Vis spectroscopy showed that the energy gap of thin films varies in the range of 3.10–3.64 eV.

Effects of Cobalt Doping on the Structural, Optical, and Electrical Properties of SnO2 Nanostructures Synthesized by SILAR Method

Undoped and cobalt (Co) doped tin oxide (SnO2) films were prepared onto glass slides via the successive ionic layer adsorption and reaction (SILAR). Variable characterization methods were applied to examine the effects of cobalt impurities on physical properties of SnO2 films. The performed characterization measurements were X-ray diffraction, Ultraviolet–visible spectrometer, Photoluminescence, and Raman. No peak ascribed to Co, SnO, or Sn was found in the XRD spectrum which may indicate the integration of cobalt in SnO2 crystal lattices. And the obtained XRD peaks may be related to the tetragonal rutile phase of pure SnO2. SEM images exposed that the Co dopant atoms affectedthe sample morphologies. The optical analyses showed that the transmittance and reflectance percentages dropped by the introduction of impurities to the SnO2 system as the absorbance values of doped SnO2 samples increased. Thus,a red shift (2.6–1.8 eV) occurred in the bandgapsas Co concentration changed in the films. The Raman spectra of pure SnO2 and Co:SnO2 samples exhibited major peaksaround 481 cm−1, 571 cm−1 and 602 cm−1. In photoluminescence spectrum, it was noted that the emission intensity can both increase or decrease due to the different cobalt doping ratios in the SnO2 nanostructures. Resistance measurements displayed that the resistivity increased with the increment of doping concentration. However, it was shown that the electrical conductivities could be increased after the heat treatment of glass substrates up to 500 oC, a common behavior of semiconductor materials.

Electron beam irradiation-induced changes in the microstructure and optoelectronic properties of nanostructured Co-doped SnO2 diluted magnetic semiconductor thin film

Electron beam irradiation-induced changes in the microstructure and optoelectronic properties of nanostructured Co-doped SnO2 diluted magnetic semiconductor thin film

Hydrothermal synthesis and their ethanol gas sensing performance of 3-dimensional hierarchical nano Pt/SnO2

A hierarchical SnO2 nanosheet structure was constructed by the hydrothermal method using hydrated stannous chloride and thiourea as raw materials. Then lysine was used as a coupling agent to load Pt nano quantum dots with different contents on the surface of the SnO2 nanosheets. The composition, morphology and structure of Pt/SnO2 were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and energy dispersive spectroscopy. The gas sensitivity of the Pt/SnO2 and SnO2 nanostructures were also studied in detail. Compared with the pure SnO2 nanosheets, the 3-dimensional structured nano 2.0% Pt/SnO2 (Pt: SnO2 = 2.0%, wt%) exhibits a higher gas sensitivity to ethanol gas at 240 °C. The gas sensitivity to 100 ppm ethanol of hierarchical nano 2.0% Pt/SnO is 2.5 times higher than pure SnO2 nanosheet, and the response time and recovery time are 4 s and 5 s, showing excellent response and recovery behavior. Meanwhile, the sensor also exhibits a lower detection limit of 0.272 ppm, as well as the excellent temperature and time stability. The higher gas sensitivity is contributed from the "spillover" effect of Pt nano quantum dots and the Schottky barrier at the heterojunctions of hierarchical Pt/SnO2 nanostructures.

Effect of rare earth doping on electronic and gas-sensing properties of SnO2 nanostructures

Tin dioxide (SnO2) and rare earth (Y, La, Pr, Tb, and Er)-doped SnO2 materials were synthesized by a solvothermal method and used for gas sensors. The effect of rare-earth (RE) doping on structural, electronic, and gas-sensing properties of SnO2 has been investigated. According to a comparative study on the gas-sensing properties of SnO2 and RE-doped SnO2 gas sensors to various testing gases, the RE-doped SnO2 sensors showed enhanced sensitivities to different testing gases. Especially, the Pr-doped SnO2 sensor exhibited outstanding sensing properties to SO2, including a high response of 19.5–50 ppm SO2, excellent selectivity, repaid response and recovery rates, and superior long-term stability. According to the structural analyses, DFT calculation, and the electrochemical measurement of the SnO2 and Pr-SnO2 materials, the improved electron excitation efficiency endowed the Pr-SnO2 with a high density of free electrons that can be trapped by atmospheric oxygen species and participated in SO2-sensing reactions. Moreover, after the Pr doping of SnO2, the enhanced charge carrier transport properties, including prolonged electron lifetime, improved electron diffusion coefficient, and increased effective diffusion length, were conducive to improving the SO2-sensing property.

Doped Tin Dioxide (d-SnO2) and Its Nanostructures: Review of the Theoretical Aspects, Photocatalytic and Biomedical Applications

Nanomaterials based on metal oxides are extensively studied for several applications due to their versatility. Improvements in their performances can be obtained due to specific structural modifications. One possible modification is by doping the crystal structure, which can affect the materials structure and properties, especially in nanosized particles. Electronic features are among the properties that can be modified through the doping process, consequently morphological and optical parameters can also be controlled by this process. In this sense, this review presents some modifications to tin dioxide (SnO2), one the most studied materials, mainly through the doping process and their impact on several properties. The article starts by describing the SnO2 structural features and the computational models used to explain the role of the doping process on these features. Based on those models, some applications of doped SnO2, such as photocatalytic degradation of pollutants, CO2 reduction, and desulfurization of fossil fuels are presented and discussed. Additionally, the review describes many biological applications related to antimicrobial activity for doped SnO2 and its nanostructures. Although most of the examples presented in this article are based on the doped SnO2, it also presents examples related to SnO2 composites with other nanomaterials forming heterojunctions. The metal oxides SnO2, doped-SnO2 and their nanostructures are promising materials, with results reported in many fields presented in this review, such as theoretical and computational chemistry, environmental remediation, nanoparticle morphology control, fossil fuels improvement, and biomedical applications. Although widely explored, there are still fields for innovation and advances with tin dioxide nanostructures, for example, in transparent conducting oxides, in forensics as materials for latent fingerprints visualization, and sensors in medicine for detection of exhaled volatile organic compounds. Therefore, this article aims to be a reference regarding correlating the doping processes and the properties presented by the SnO2 nanostructures.

Influence of relative humidity on CO2 interaction mechanism for Gd-doped SnO2 with respect to pure SnO2 and Gd2O3

The paper aims to identify the CO2 interaction mechanism for chemical sensors based on Gd-doped SnO2, SnO2 and Gd2O3 powders deposited as thick sensitive layers. The low reactivity of CO2 conferred by the thermodynamic stability and chemical inertia can be offset by the presence of relative humidity. The sensitive powders were prepared by wet chemical co-precipitation method. The Gd concentration was varied from 1% to 20 at% in order to determine the limit for Gd integration as a doping ion prior to chemical segregation as a secondary phase. Analytical transmission electron microscopy points to a homogeneous Gd doping of the nanostructured SnO2 powders for low doping concentrations and the formation of a nanocomposite based on SnO2 as main phase and cubic Gd2O3 as secondary phase for the highly doped samples. The electrical resistance is either influenced by the density of oxygen vacancies, or is the result of compensation for two opposite behaviours into the SnO2-Gd2O3 nanocomposite structures. The CO2 exposure to humid atmosphere determines distinct behaviours corresponding to SnO2 and Gd2O3 as constitutive elements. The associated CO2 interaction mechanism is based on simultaneous DC electrical resistance and Contact Potential Difference measurements, which allow decoupling the ionosorption from the dipolar processes, thus highlighting specific chemical interactions on the SnO2 and Gd2O3 surfaces.

Ceramic Catalysts: Materials, Synthesis, and Applications

We report a facile synthesis of nanostructured Cu-incorporated SnO2. Aggregates composed of uniform ∼ 5 nm-sized nanoparticles were obtained through a simple room-temperature reaction between CuO and SnC2O4 in aqueous solution. The material is single-phase with copper incorporated mainly as Cu+. The synthesis approach also allows mixing with CuO to prepare SnO2/CuO nanocomposites. The synthesized materials show an improved cycle performance as anode materials in lithium ion batteries due to an improved morphology and in situ formation of metallic copper upon cycling (in the voltage range 0.05–1.1 V vs. Li/Li+).