Crystalline SnO2 Research Articles

Optimization of Al2O3 shell thickness on SnO2 nanowires for realization of sensitive and selective H2 sensing

Detection of highly explosive H2 gas is a critical safety issue. Herein, using a vapor-liquid-solid growth mechanism, SnO2 nanowires (NWs) were prepared, after which Al2O3 shells (1.9, 3.3, 4.5, and 6.1 nm) were deposited on synthesized SnO2 NWs by atomic layer deposition. Based on characterization studies, C-S NW structures with a crystalline SnO2 core and amorphous Al2O3 shell were successfully formed. Based on H2 gas sensing measurement, SnO2-Al2O3 (4.5 nm) C-S NWs exhibited a high response of 152.54 to H2 (10 ppm) at 350°C. Furthermore, they showed excellent selectivity, where response to H2 gas (10 ppm) was more than 33 times higher than that to NO2 gas (10 ppm). Additionally, they displayed excellent repeatability as well as long-term stability in detection of low-concentration H2 gas. The improved H2 sensing capability was related to the high base resistance, the formation of the SnO2-Al2O3 heterojunction, the optimization of the Al2O3 shell thickness on SnO2 NWs, and the partial reduction of SnO2 and Al2O3 in an H2 gas atmosphere. This study sheds light on the development of H2 sensors based on present material.

Facile Synthesis, Sintering, and Optical Properties of Single-Nanometer-Scale SnO2 Particles with a Pyrrolidone Derivative for Photovoltaic Applications

We investigate the preparation of mesoscopic SnO2 nanoparticulate films using a Sn(IV) hydrate salt combined with a liquid pyrrolidone derivative to form a homogeneous precursor mixture for functional SnO2 nanomaterials. We demonstrate that N-methyl-2-pyrrolidone (NMP) plays a crucial role in forming uniform SnO2 films by both stabilizing the hydrolysis products of Sn(IV) sources and acting as a base liquid during nanoparticle growth. The hydrolysis of Sn(IV) was controlled by adjusting the reaction temperature to as low as 110 °C for 48 h. High-resolution TEM analysis revealed that highly crystalline SnO2 nanoparticles, approximately 3–5 nm in size, were formed. The SnO2 nanoparticles were deposited onto F-doped SnO2 glass and converted into dense particle films through heat treatments at 400 °C and 500 °C. This pyrrolidone-based nanoparticle synthesis enabled the production of not only crystallized SnO2 but also transparent and uniform films, most importantly by controlling the slow hydrolysis of Sn(IV) and polycondensation only with those two chemicals. These findings offer valuable insights for developing stable and uniform electron transport layers of SnO2 in mesoscopic solar cells, such as perovskite solar cells.

A mechanism study of type i corrosion on the surface of ancient tin rich bronzes

This study compares the surface patina of ancient tin rich bronze with pure hydrothermally synthesized SnO2 nanoparticles using various analytical techniques, including metallographic microscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy. The primary crystalline component of the patina consists of approximately 5 nm SnO2 nanoparticles, which closely resemble pure SnO2, indicating their comparability. Cu was also detected in the patina; however, it did not form crystalline structures. The X-ray diffraction results showed a shift in the patina’s peak, suggesting the infiltration of Cu into the SnO2 lattice, which compromises its crystallinity. In comparison to synthetic SnO2, the X-ray photoelectron spectroscopy spectra of the patina revealed novel peaks corresponding to both Cu and O, indicating the presence of Cu−O−Sn bonding—a characteristic feature of type-I patina. This suggests that the primary structure of type-I patina consists of crystalline SnO2 nanoparticles, with a limited amount of Cu integrated into its lattice configuration. The concentration of Cu within the SnO2 crystal units is restricted, leading primarily to the formation of amorphous Cu2O in conjunction with Sn. The presence of Sn enhances the structural stability of Cu2O, facilitating its incorporation while inhibiting the crystallization of Cu2O. However, when the Sn concentration is insufficient, an inadequate Cu–O−Sn amorphous phase may form, allowing for the potential crystallization of Cu2O.

SnO2QDs: Photophysical properties, photocatalytic activity, mineralization financial cost and recycling process during industrial effluent treatment

This study investigates the synthesis, characterization, and photocatalytic performance of pure and titanium-doped tin dioxide quantum dots (SnO2QDs) prepared via a sonochemical method. The structural and morphological properties were thoroughly examined using XRD, FTIR, SEM-EDX, HRTEM, UV-DRS, and BET surface area analysis. XRD confirmed the formation of tetragonal SnO2 with high phase purity and average crystallite sizes of 2.95 nm for SnO2QD1 (calcined at 270 °C) and 8.36 nm for SnO2QD2 (calcined at 480 °C). Titanium doping was achieved without altering the SnO2 crystalline structure, as evidenced by FTIR spectra showing characteristic vibrational modes and hydroxyl groups. HRTEM images revealed spherical nanoparticles with diameters of 3.2 nm for SnO2QD1 and 9.7 nm for SnO2QD2, supported by SAED patterns confirming their polycrystalline nature. The photocatalytic efficiency was evaluated through the degradation of Reactive Yellow 145 dye under Xenon lamp irradiation. SnO2QD1 exhibited superior photocatalytic activity with a rate constant (k) of 6.94 × 10−3 s−1, achieving 80 % dye degradation in 105 min, compared to SnO2QD2 with a k of 4.50 × 10−3 s−1 and 83 % degradation in 120 min. Titanium doping further enhanced the photocatalytic performance, with SnO2QDT1 (1 % Ti) showing a k of 9.89 × 10−3 s−1 and 80 % degradation in just 90 min, three times more efficient than SnO2QDT2 (9 % Ti). BET analysis indicated a significant reduction in surface area with increased calcination temperature, from 154 m2/g for SnO2QD1 to 86 m2/g for SnO2QD2. The bandgap energies, determined via UV-DRS, were 3.30 eV for SnO2QD1 and 3.34 eV for SnO2QD2, slightly reduced in Ti-doped samples, enhancing visible light absorption. The SnO2QDs demonstrated excellent recyclability, maintaining photocatalytic activity over eight reuse cycles. Economic analysis based on Saudi Arabian electricity tariffs highlighted the cost-effectiveness of SnO2QD1, offering a 5.2 % reduction in energy consumption compared to SnO2QD2. These findings position SnO2QDs as highly efficient and sustainable photocatalysts for industrial wastewater treatment applications.

Enhancement of optical and electrical properties of tin oxide thin films through Zr + Ag doping for photocatalytic and photovoltaic applications

Abstract In present investigation, Pure Tin (Sn), Zirconia (Zr) and Silver (Ag) doped Sn thin films are prepared by jet nebuliser spray technique and utilised for possible photovoltaic application. A simple soft chemical technique used to create Zr and Ag doped SnO2 nanocrystalline nanoparticles. As shown by the results of the XRD analysis, the nanoparticles found a tetragonal structure with P42/mnm symmetry, in accordance with the appearance of highly crystalline SnO2. The optical properties were performed, and their bandgap energies were found to be 2.8, 3.1 and 3.2 eV, respectively. Particles of prepared SnO2 were analysed using FT-IR and XRD spectroscopy, which confirmed the presence of Zr and Ag. The photocatalytic performance of Sn–Zr–Ag NPs was examined by degradation of cationic Safranin dye under sunlight radiations with an interval of 15 min up to 90 min. UV–Vis spectrum analysis and a pseudo-first-order kinetics model were used to study nano catalytic dye degradation. High photocatalytic activities were observed after Zr and Ag doping, which may be enhanced further by adding H2O2. The surface characteristics of the prepared thin films are evaluated by AFM analysis. The electrochemical behaviour and photovoltaic properties are evaluated by EIS and IV characteristic studies.

Completely annealing-free flexible Perovskite quantum dot solar cells employing UV-sintered Ga-doped SnO2 electron transport layers

The electron transport layer (ETL) is a critical component in perovskite quantum dot (PQD) solar cells, significantly impacting their photovoltaic performance and stability. Low-temperature ETL deposition methods are especially desirable for fabricating flexible solar cells on polymer substrates. Herein, we propose a room-temperature-processed tin oxide (SnO2) ETL preparation method for flexible PQD solar cells. The process involves synthesizing highly crystalline SnO2 nanocrystals stabilized with organic ligands, spin-coating their dispersion, followed by UV irradiation. The energy level of SnO2 is controlled by doping gallium ions to reduce the energy level mismatch with the PQD. The proposed ETL-based CsPbI3-PQD solar cell achieves a power conversion efficiency (PCE) of 12.70%, the highest PCE among reported flexible quantum dot solar cells, maintaining 94% of the initial PCE after 500 bending tests. Consequently, we demonstrate that a systemically designed ETL enhances the photovoltaic performance and mechanical stability of flexible optoelectronic devices.

Inkjet-printed SnOx as an effective electron transport layer for planar perovskite solar cells and the effect of Cu doping.

Inkjet printing is a more sustainable and scalable fabrication method than spin coating for producing perovskite solar cells (PSCs). Although spin-coated SnO2 has been intensively studied as an effective electron transport layer (ETL) for PSCs, inkjet-printed SnO2 ETLs have not been widely reported. Here, we fabricated inkjet-printed, solution-processed SnOx ETLs for planar PSCs. A champion efficiency of 17.55% was achieved for the cell using a low-temperature processed SnOx ETL. The low-temperature SnOx exhibited an amorphous structure and outperformed high-temperature crystalline SnO2. The improved performance was attributed to enhanced charge extraction and transport and suppressed charge recombination at ETL/perovskite interfaces, which originated from enhanced electrical and optical properties of SnOx, improved perovskite film quality, and well-matched energy level alignment between the SnOx ETL and the perovskite layer. Furthermore, SnOx was doped with Cu. Cu doping increased surface oxygen defects and upshifted energy levels of SnOx, leading to reduced device performance. A tunable hysteresis was observed for PSCs with Cu-doped SnOx ETLs, decreasing at first and turning into inverted hysteresis afterwards with increasing Cu doping level. This tunable hysteresis was related to the interplay between charge/ion accumulation and recombination at ETL/perovskite interfaces in the case of electron extraction barriers.

Assessing the key parameters for efficient sensitized infrared emission from erbium-doped SnO2 films

Erbium-doped SnO2 films (Er:SnO2) combine the properties of Er3+ and SnO2, providing an avenue for developing unique luminophores with sensitized infrared emission. In such a system, Er3+ luminescence evolves over doping-concentration and thermal-treatment shifts, where low-temperature-annealed or highly-doped Er:SnO2 exhibits degraded emission. To fully exploit the potential of Er:SnO2, a deep understanding of the underlying physical process is required. This paper discusses the parameters determining the intensity of sensitized Er3+ emission and their evolution with doping concentration and thermal treatment. The observation of temperature-independent decay of Er3+ luminescence excludes the nonradiative interaction of the Er3+4I13/2 → 4I15/2 transition with defects in SnO2. Moreover, despite the loss of Er3+ optical activity observed in highly-doped or low-temperature-annealed samples, the sensitized emission intensity doesn't scale linearly with it. Instead, the most prominent parameter determining the sensitized emission intensity is found to be the energy transfer efficiency from SnO2 to Er3+, which highly depends on the crystallinity of SnO2. The presence of defects in low-crystallinity SnO2, that is, highly-doped or low-temperature-annealed ones, would deteriorate the energy transfer efficiency, which could be healed by high-temperature annealing. This work negates the traditional consensus of concentration quenching in Er:SnO2 and provides an important insight into developing efficient Er:SnO2 based infrared luminophores.

Surface-Enhanced Raman Spectroscopy for Boosting Electrochemical CO2 Reduction on Amorphous-Surfaced Tin Oxide Supported by MXene.

Amorphous materials disrupt the intrinsic linear scalar dependence seen in their crystalline counterparts, typically exhibiting enhanced catalytic characteristics. Nevertheless, substantial obstacles remain in terms of boosting their stability, enhancing their conductivity, and elucidating distinct catalytic mechanisms. Herein, a core-shell catalyst, comprising a crystalline SnO2 core and an amorphous SnOx shell supported on MXene (denoted as SnO2@SnOx/MXene), was prepared utilizing hydrothermal and solution reduction methods. The SnO2@SnOx/MXene catalyst excels in the electrocatalytic conversion of CO2 to formate, yielding a Faradaic efficiency (FE) as high as 93% for formate production at -1.17 V vs RHE and demonstrating exceptional durability. Both density functional theory (DFT) calculations and experimental results indicate that the SnOx shell bolsters formate formation by fine-tuning the adsorption energy of the *OCHO intermediate. In SnO2@SnOx/MXene, MXene plays a vital role in enhancing the conductivity and stability of the amorphous shell and especially amplifying Raman signals of catalyst components. The ex/in situ surface-enhanced Raman scattering (SERS) application further confirms the formation of amorphous SnOx and further enables the direct detection of the formation of the intermediate species. This work provides the basis for the application of amorphous materials in practical electrocatalytic reduction of CO2 reduction.

Photoexcitation-induced passivation of SnO2 thin film for efficient perovskite solar cells.

A high-quality tin oxide electron transport layer (ETL) is a key common factor to achieve high-performance perovskite solar cells (PSCs). However, the conventional annealing technique to prepare high-quality ETLs by continuous heating under near-equilibrium conditions requires high temperatures and a long fabrication time. Alternatively, we present a non-equilibrium, photoexcitation-induced passivation technique that uses multiple ultrashort laser pulses. The ultrafast photoexcitation and following electron-electron and electron-phonon scattering processes induce ultrafast annealing to efficiently passivate surface and bulk defects, and improve the crystallinity of SnO2, resulting in suppressing the carrier recombination and facilitating the charge transport between the ETL and perovskite interface. By rapidly scanning the laser beam, the annealing time is reduced to several minutes, which is much more efficient compared with conventional thermal annealing. To demonstrate the university and scalability of this technique, typical antisolvent and antisolvent-free processed hybrid organic-inorganic metal halide PSCs have been fabricated and achieved the power conversion efficiency (PCE) of 24.14% and 22.75% respectively, and a 12-square-centimeter module antisolvent-free processed perovskite solar module achieves a PCE of 20.26%, with significantly enhanced performance both in PCE and stability. This study establishes a new approach towards the commercialization of efficient low-temperature manufacturing of PSCs.

Facilitating the formation of SnO2 film via HfO2-modified FTO electrode for efficient perovskite solar cells

Fabricating a dense and crystalline SnO2 film has been an important step for efficient SnO2-based perovskite solar cells (PSCs). Herein, a wide bandgap material, HfO2, was deposited on the surface of FTO to facilitate the formation of an SnO2 film. It was found that the HfO2 modification on FTO could significantly improve the crystallization of the upper SnO2 film and passivate the trap states within the SnO2 layer. Moreover, the high conduction band level of HfO2 can block the backflow of electrons and suppress the nonradiative recombination of carriers. Eventually, the best PSC with HfO2 interlayer presented a power conversion efficiency (PCE) of 21.13% with a VOC of 1.13 V, which are higher than those of the reference device. This study provides a meaningful strategy for ETL optimization to further increase the efficiency of the SnO2-based PSCs.

Active sites tailored rGO-PPy nanosheets with high crystalline tetragonal SnO2 nanocrystals for ammonia e-sensitization at room temperature

Hybrid material-based gas sensors are emerging devices in the field of gas sensing. In this present work, we report SnO2 calcinated at two different temperatures (500SnO2 and 600SnO2) and made a composite with reduced graphene oxide (rGO) and polypyrrole (PPy) nanosheets, which resulted in excellent electronic and structural properties that exhibited improved gas sensing performance at the ternary hybrid (rGO-PPy-600SnO2). The physical and chemical properties of the hybrid rGO-PPy-600SnO2 were studied using different techniques such as UV–vis spectroscopy, XRD, FTIR, XPS, SEM, HRTEM, CV, and EIS, as well as the hybrid's sensing performance. The chemo-resistive-type gas sensor was created, and its sensing responses to several gases (NH3, H2, LPG, and CO2) were examined. The findings showed that the ternary hybrid rGO-PPy-600SnO2 had a higher sensing response to NH3 gas than other gases, with the highest sensitivity of 53%, a quick response time of 44 s, and a recovery time of 45 s for 10-ppm ammonia. This enhanced sensing behavior was caused by electronic sensitization between the p-n heterojunctions and can detect up to 4.04 ppm of ammonia at room temperature. The electrode could maintain 88% stability for 50 days. This straightforward and affordable method will be a contender for producing ammonia gas sensors that can function at room temperature.

SnO2 nanostructured thin film as humidity sensor and its application in breath monitoring

In the present paper, we studied SnO2 nanostructured thin film-based resistive type humidity sensor fabricated by spin coating method on alumina substrate and showed its application in real time respiratory monitoring. Experiments show the growth of crystalline SnO2 nanoparticles with a tetragonal phase, with an average particle size of ∼15 nm and a high surface roughness of the order of 50-60 nm. The gold-interdigitated electrodes were patterned on the SnO2 film surface by DC sputtering technique to study the sensing response of the film. The sensor shows a high sensitivity of 1.34 kΩ/%RH, a minimal hysteresis of 0.94%, and good repeatability. The developed sensor is tested for monitoring human breath patterns in different physical conditions, and apnea like situations, which suggests its potential for clinical applications. Overall, the present work proposes an environmental friendly, easy-to-synthesize, highly stable, and simple facile SnO2 based deployable humidity sensor to diagnose human health patterns in a non-contact manner.

Acceptor and compensating donor doping of single crystalline SnO (001) films grown by molecular beam epitaxy and its perspectives for optoelectronics and gas-sensing

(La and Ga)-doped tin monoxide [stannous oxide, tin (II) oxide, SnO] thin films were grown by plasma-assisted and suboxide molecular beam epitaxy with dopant concentrations ranging from ≈ 5 × 1018 to 2 × 1021 cm−3. In this concentration range, the incorporation of Ga into SnO was limited by the formation of secondary phases observed at 1.2 × 1021 cm−3 Ga, while the incorporation of La showed a lower solubility limit. Transport measurements on the doped samples reveal that Ga acts as an acceptor and La as a compensating donor. While Ga doping led to an increase in the hole concentration from 1 × 1018−1 × 1019 cm−3 for unintentionally doped (UID) SnO up to 5 × 1019 cm−3, La-concentrations well in excess of the UID acceptor concentration resulted in semi-insulating films without detectable n-type conductivity. Ab initio calculations qualitatively agree with our dopant assignment of Ga and La and further predict InSn to act as an acceptor as well as AlSn and BSn as donors. These results show the possibilities of controlling the hole concentration in p-type SnO, which can be useful for a range of optoelectronic and gas-sensing applications.

Microstructure and photocatalytic activity of SnO2:Bi3+ nanoparticles

SnO2:Bi3+ nanoparticles were synthesized by a one-step hydrothermal method. The influence of Bi3+ impurity concentrations on SnO2:Bi3+ samples was deeply investigated by studying the changes in size, morphology, and band gap width of SnO2:Bi3+ materials. In addition, the interaction between the SnO2 crystalline host and Bi3+ was studied in detail by several characterization techniques, such as SEM, XRD, UV–Vis, PL, and EPR. We also investigated the photocatalytic activity of the SnO2:Bi3+ nanoparticles by photodegrading methylene blue (MB), rhodamine B (RhB), and phenol under visible light. The photocatalytic efficiency of the SnO2:Bi3+ nanoparticles was higher than that of pure SnO2 nanoparticles. The photocatalytic degradation efficiency of SnO2:Bi3+-2% for MB was up to 52% and 15%–20% for the other samples. The photocatalytic degradation efficiency of SnO2:Bi3+-2% for RhB is up to 65% and that of the remaining samples is 25%–46%. The high degradation efficiency of the SnO2:Bi3+-2% sample was due to its small crystal size, which increased the specific surface area, resulting in higher photocatalytic efficiency. In addition, the high photocatalytic efficiency of the SnO2:Bi3+-2% sample is related to the defect states, increasing the surface charge carrier transfer rate and reducing the electron–hole recombination rate. Meanwhile, the photocatalytic efficiency of the SnO2:Bi3+ nanoparticles for phenol is 41% and 43% with SnO2:Bi3+-6% and −8% samples, respectively, and that of the remaining samples is 32%–34%. This finding is explained by the interaction between Bi3+ ions and phenol molecules, increasing the photocatalytic efficiency. This work increases the feasibility of degrading environmental pollutants using SnO2:Bi3+ photocatalysts with high efficiency.

Oxygen Aspects in the High-Pressure and High-Temperature Sintering of Semiconductor Kesterite Cu2ZnSnS4 Nanopowders Prepared by a Mechanochemically-Assisted Synthesis Method

We explore the important aspects of adventitious oxygen presence in nanopowders, as well as in the high-pressure and high-temperature-sintered nanoceramics of semiconductor kesterite Cu2ZnSnS4. The initial nanopowders were prepared via the mechanochemical synthesis route from two precursor systems, i.e., (i) a mixture of the constituent elements (Cu, Zn, Sn, and S), (ii) a mixture of the respective metal sulfides (Cu2S, ZnS, and SnS), and sulfur (S). They were made in each system in the form of both the raw powder of non-semiconducting cubic zincblende-type prekesterite and, after thermal treatment at 500 °C, of semiconductor tetragonal kesterite. Upon characterization, the nanopowders were subjected to high-pressure (7.7 GPa) and high-temperature (500 °C) sintering that afforded mechanically stable black pellets. Both the nanopowders and pellets were extensively characterized, employing such determinations as powder XRD, UV-Vis/FT-IR/Raman spectroscopies, solid-state 65Cu/119Sn NMR, TGA/DTA/MS, directly analyzed oxygen (O) and hydrogen (H) contents, BET specific surface area, helium density, and Vicker's hardness (when applicable). The major findings are the unexpectedly high oxygen contents in the starting nanopowders, which are further revealed in the sintered pellets as crystalline SnO2. Additionally, the pressure-temperature-time conditions of the HP-HT sintering of the nanopowders are shown (in the relevant cases) to result in the conversion of the tetragonal kesterite into cubic zincblende polytype upon decompression.

Amorphous F‐doped TiOx Caulked SnO2 Electron Transport Layer for Flexible Perovskite Solar Cells with Efficiency Exceeding 22.5%

AbstractFlexible perovskite solar cells (f‐PSCs) show great promise in portable‐power applications (e.g., chargers, drones) and low‐cost, scalable productions (e.g., roll‐to‐roll). However, in conventional n–i–p architecture f‐PSCs, the low‐temperature processed metal oxide electron transport layers (ETLs) usually suffer from high resistance and severe defects that limit the power conversion efficiency (PCE) improvement of f‐PSCs. Besides the enhancement in the mobility of metal oxide and passivation for perovskite/ETL interfacial defects reported in previous literature, herein, the electron transport loss between the metal oxide nanocrystallines within the ETL is studied by introducing an amorphous F‐doped TiOx (F‐TiOx) caulked crystalline SnO2 composite ETL. The F‐TiOx in this novel composite ETL acts as an interstitial medium between adjacent SnO2 nanocrystallines, which can provide more electron transport channels, effectively passivate oxygen vacancies, and optimize the energy level arrangement, thus significantly enhancing the electron mobility of ETL and reducing the charge transport losses. The composite ETL‐based f‐PSCs achieve a high PCE of 22.70% and good operational stability. Furthermore, a moderate roughness of the composite ETL endows f‐PSCs with superior mechanical reliability by virtue of a strong coupling at the ETL/perovskite interface, by which the f‐PSCs can maintain 82.11% of their initial PCE after 4000 bending cycles.

A Stable Aqueous SnO2 Nanoparticle Dispersion for Roll-to-Roll Fabrication of Flexible Perovskite Solar Cells

Perovskite solar cells (PSCs) are attracting increasing commercial interest due to their potential as cost-effective, lightweight sources of solar energy. Low-cost, large-scale printing and coating processes can accelerate the development of PSCs from the laboratory to the industry. The present work demonstrates the use of microwave-assisted solvothermal processing as a new and efficient route for synthesizing crystalline SnO2 nanoparticle-based aqueous dispersions having a narrow particle size distribution. The SnO2 nanoparticles are analyzed in terms of their optical, structural, size, phase, and chemical properties. To validate the suitability of these dispersions for use in roll-to-roll (R2R) coating, they were applied as the electron-transport layer in PSCs, and their performance was compared with equivalent devices using a commercially available aqueous SnO2 colloidal ink. The devices were fabricated under ambient laboratory conditions, and all layers were deposited at less than 150 °C. The power conversion efficiency (PCE) of glass-based PSCs comprising a synthesized SnO2 nanoparticle dispersion displayed champion levels of 20.2% compared with 18.5% for the devices using commercial SnO2 inks. Flexible PSCs comprising an R2R-coated layer of synthesized SnO2 nanoparticle dispersion displayed a champion PCE of 17.0%.

A comparison between growth of direct and pulse current electrodeposited crystalline SnO2 films; electrochemical properties for application in lithium-ion batteries

Tin oxide (SnO2) films were electrodeposited on graphite substrates using direct and pulse current electrodeposition techniques. The influence of applied current density on the morphological properties, crystal structure, and electrochemical behavior of the resulting films were studied by scanning electron microscope, X-ray diffraction spectroscopy, Mott–Schottky analysis, cyclic voltammetry, and electrochemical impedance spectroscopy techniques. The results showed that pulse electrodeposited films have porous flower-like morphology with smaller crystallite size and high donor density in comparison with direct current electrodeposited films that include equiaxed particles in their morphologies, such characteristics give them better electrochemical performance (higher degree of reversibility, higher specific capacitance, and faster lithium-ion diffusion) than those films that were synthesized by conventional direct current electrodeposition method. Furthermore, using higher applied current densities leads to the improvement of SnO2 films’ electrochemical performance due to the formation of the films with finer morphology that include more porosity and oxygen vacancies in their respective crystal structure.

Photocatalytic and biological activities of green synthesized SnO2 nanoparticles using Chlorella vulgaris

To produce tin oxide (SnO2 ) nanoparticles (NP) with microalga for use in azo dye-polluted wastewater treatment and to optimize the conditions to synthesize as small NPs as possible. The green microalga Chlorella vulgaris mediated NPs were synthesized after an optimization process utilizing the statistical response surface methodology (RSM). The optimized synthesis conditions were 200 W microwave power, 0.5 mM SnCl2 concentration and 200°C calcination temperature. Methyl orange (MO) was studied for its photocatalytic degradation with UV. Antibacterial activity against four pathogenic bacteria was studied using the well diffusion method. Cytotoxicity was measured using the MMT assay with lung cancer cell line A549, and antioxidant activity using DPPH radical scavenging. Following the optimization of their production, the produced crystalline SnO2 NPs were on average 32.2nm (by XRD) with a hydrodynamic size of 52.5nm (by LDS). Photocatalytic degradation of MO under UV was nearly complete (94% removal) after 90 min and the particles could be reused for 5cycles retaining 80% activity. The particles had antibacterial activity towards all five tested bacterial pathogens with the minimum inhibitory concentrations ranging from 22 to 36 μg/ml. The minimum bactericidal NP concentration varied between 83 and 136 μg/ml. Antioxidant activity was concentration dependent. A cytotoxicity was determined towards A549 cells with an LD50 of 188 μg/ml after 24 h of incubation, a concentration that is much higher than the active concentration for dye removal ranging from 22 to 36 μg/ml. After optimization, SnO2 nanoparticles produced with C. vulgaris displayed high photocatalytic activity at concentrations below their antibacterial and cytotoxic activities. The SnO2 nanoparticles produced with the help of microalgae are suitable for the removal of MO dye from wastewater. Further applications of this green technology can be expected.