Tin dioxide buffer layer-assisted efficiency and stability of wide-bandgap inverted perovskite solar cells

Inverted perovskite solar cells(IPSCs) have attracted tremendous research interest in recent years due to their applications in perovskite/silicon tandem solar cells. However, further performance improvements and long-term stability issues are the main obstacles that deeply hinder the development of devices. Herein, we demonstrate a facile atomic layer deposition(ALD) processed tin dioxide(SnO2) as an additional buffer layer for efficient and stable wide-bandgap IPSCs. The additional buffer layer increases the shunt resistance and reduces the reverse current saturation density, resulting in the enhancement of efficiency from 19.23% to 21.13%. The target device with a bandgap of 1.63 eV obtains open-circuit voltage of 1.19 V, short circuit current density of 21.86 mA/cm^(2), and fill factor of 81.07%. More importantly, the compact and stable SnO_(2) film invests the IPSCs with superhydrophobicity, thus significantly enhancing the moisture resistance. Eventually, the target device can maintain 90% of its initial efficiency after 600 h storage in ambient conditions with relative humidity of 20%–40% without encapsulation. The ALD-processed SnO_(2) provides a promising way to boost the efficiency and stability of IPSCs, and a great potential for perovskite-based tandem solar cells in the near future.

Low temperature H_2S sensor based on copper oxide/tin dioxide thick film

Nanostructured tin dioxide （SnO2） powders were prepared by a sol-gel dialytic process and and the doping of CuO on it was completed by a deposition-precipitation method.The thick film sensors were fabricated from the CuO/SnO2 polycrystalline powders.Sensing behavior of the sensor was investigated with various gases including CO,H2,NH3,hexane,acetone,ethanol,methanol and H2S in air.The as-synthesized gas sensor had much better response to H2S than to other gases.At the same time,the CuO/SnO2 sensor had enough sensitivity,together with fast response and recovery,to distinguish H2S from those gases at 160 and 210 ℃.Therefore,it might have promising applications in the future.

Copper Ion Beam Irradiation-Induced Effects on Structural,Morphological and Optical Properties of Tin Dioxide Nanowires

The 0.8 Me V copper （ Cu） ion beam irradiation-induced effects on structural, morphological and optical properties of tin dioxide nanowires （Sn02 NWs） are investigated. The samples are irradiated at three different doses 5 × 10^12 ions/cm2, 1 ×10^13 ions/cm2 and 5 × 10^13 ions/em2 at room temperature. The XRD analysis shows that the tetragonal phase of Sn02 NWs remains stable after Cu ion irradiation, but with increasing irradiation dose level the crystal size increases due to ion beam induced coalescence of NWs. The FTIR spectra of pristine Sn02 NWs exhibit the chemical composition of SnO2 while the Cn-O bond is also observed in the FTIR spectra after Cu ion beam irradiation. The presence of Cu impurity in SnO2 is further confirmed by calculating the stopping range of Cu ions by using TRM/SRIM code. Optical properties of SnO2 NWs are studied before and after Cu ion irradiation. Band gap analysis reveMs that the band gap of irradiated samples is found to decrease compared with the pristine sample. Therefore, ion beam irradiation is a promising technology for nanoengineering and band gap tailoring.

Large Mesoporous Tin Dioxide Powders for Gas Sensor Materials-Effects of Various Additives on the Mesostructure and the H_2 Sensing Properties

Preparation of large mesoporous tin dioxide (lm-SnO_2) under various conditions was attempted by utilizing a self-assembly of a triblock copolymer,P123:(EO)_(20)(PO)_(70)(EO)_(20) or F127:(EO)_(106)(PO)_(70)(EO)_(106)(EO:ethylene oxide and PO: propylene oxide).The sensor fabricated from calcined lm-SnO_2 powder,which had been prepared by using P123 as a template,Na_2SnO_3 as a tin source,and TEOS as an additive ([TEOS]/[Na_2SnO_3]=0.5 in the precursor solution),showed the largest response to 1×10^(-3) hydrogen at 350℃among the sensors tested.The existence of two kinds of SnO_2 particles with different sizes (ca.100 nm and several nm in diameter) may be important to improve the hydrogen sensing properties drastically.

Gadolinium doped tin dioxide nanoparticles: an efficient visible light active photocatalyst

Photocatalytic degradation of phenol with sol-gel prepared rare earth doped tin dioxide （SnO2） nanoparticles was reported. Gadolinium doped tin dioxide （SnO2：Gd） nanoparticles were found to absorb higher visible light compared to lanthanum, neodymium and cerium doped materials that were studied in detail. Photocatalytic degradation of phenol under artificial white light and sunlight in the presence of SnO2：Gd nanoparticles was studied with high performance liquid chromatography （HPLC）, capillary electrophoresis （CE）, total organic carbon （TOC） measurements and the determination of chemical oxygen demand （COD）. Clear correlations be- tween the results obtained from these multiple measurements were found, and a kinetic pathway for the degradation process was pro- posed. Within 150 min of solar irradiation, the TOC of a 10 ppm phenol solution in water was reduced by 95%-99%, thus demon- strating that SnO2：Gd nanoparticles are efficient visible light photocatalysts.

Recent research situation in tin dioxide nanomaterials： synthesis, microstructures, and properties

This review article summarizes the new research in solid-state physical chemistry understanding of the microstructure characteristics of semiconductor tin oxide thin films made in the last years in our group. The work mainly focuses on the fabrication technology of semiconductor tin oxides thin films by using pulsed laser deposition （PLD） as well as the application of this technology on new micro- and nanostructured materials. It is an interdisciplinary work that integrates the areas of physics, chemistry and materials science.

Synthesis of mesoporous tin dioxide via sol-gel process assisted by resorcinol-formaldehyde gel

Tin dioxide is a useful n-type oxide semiconductor used in a variety of applications owing to its superior optical, electrical, and multifunctional properties. Here, we used a network of resorcinol-formaldehyde （RF） gel to synthesize mesoporous tin dioxide via a sol-gel process. The effects of various synthesis parameters on the morphology and mesoporosity of the obtained product were investigated, including aging time of the RF gel, tin-to-formaldehyde molar ratio, resorcinol-to-carbonate molar ratio, and the aging time of the tin/RF mixed gel. Our experimental results showed that the interaction between the network of the RF gel and tin-containing sol is a key factor that affected the structural strength of the porous network and the porosity of the final product. Through control of the interactions in the tin/RF mixed gel we obtained porous tin dioxide materials that could be effectively used to form large-surface area films with desirable mesoporous properties.

Synthesis of Tin Oxide Through Thermal Decomposition of Sn_2(NH_4)_2(C_2O_4)_3 and Its Gas Sensing Property

Nanocrystalline tin oxide samples were prepared by using Sn2 （NH4 ）2 （C2O4）3 as the precursor. The thermal decompositions were respectively conducted at 250,450 and 650 ℃. TG-DTA, XRD, TEM, FTIR were used to characterize the samples. The indirect heating sensors by using these materials as sensitive bodies were fabricated on an alumina tube with Au electrodes and platinum wires. Sensing properties of these sensors were investigated. It was found that the tin oxide sample obtained by thermal decomposition at 450 ℃ has a higher sensitivity to C2H5OH and a higher selectivity to hexane and ammonia than those obtained via the conventional precipitate method and the working temperatures needed were greatly decreased.

Photocatalytic degradation of Acid Blue 62 over CuO-SnO_2 nanocomposite photocatalyst under simulated sunlight

The novel CuO-SnO2 nanocomposite oxide photocatalysts were prepared by simple co-precipitation method, and characterized by X- ray diffraction, transmission electron microscopy, N2 adsorption-desorption measurement and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activities of CuO-SnO2, evaluated using the photodegradation of Acid Blue 62 as a probe reaction under the irradiation of Xenon light, were also found to be related to the calcination temperature and the molar ratio of Cu to Sn. The maximum photocatalytic activity of the CuO-SnO2 photocatalyst was observed to be calcined at 500~C for 3 h （the molar ratio of Cu to Sn was 1：1） due to the sample with good crystallization and high surface area. It also showed much higher photocatalytic activity in treatment dye wastewater under simulated sunlight irradiation compared to Degussa P25 TiO2.

Synthesis of SnO_2 nanorods from aqueous solution:The effect of preparation conditions on the formed patterns

SnO2 nanorods were deposited on the Si substrates in an aqueous solution containing both SnCl4 and CO（NH2）2.It is found that different self-assembled patterns of SnO2 nanorods can be obtained by changing the deposition conditions such as the molar ratio of CO（NH2）2 to SnCl4 and the pretreatment of the substrate.Scattered SnO2 nanorods,for example,can be changed into flower-like patterns when the molar ratio of CO（NH2）2 to SnCl4 is raised,and well-aligned nanorod arrays can be formed when the pretreatment of the substrate is changed.In addition,some interesting patterns,e.g.tree-like patterns,can also be observed.

Soft template synthesis of high selectivity mesoporous SnO_2 gas sensors

Mesoporous SnO2 was synthesized using cetyltrimethyl ammonium bromide （CTAB） as supermolecule-template by hydrothermal method followed by calcining under different temperature in air. X-ray diffraction analysis （XRD） and transmission electron microscopy （TEM） techniques were used to characterize the structure of mesoporous SnO2. The results indicated that the gas sensors prepared by using mesoporous SnO2 after calcination at 400 ℃ showed quick response and recovery to ethanol at 200 ℃. It was also found that the mesostructure SnO2 with small particle size had higher sensitivity and selectivity to C2HhOH than the SnO2 nanoparticles the particle size of which is 20 nm synthesized by sol-gel method.

Preparation and characterization of oil-soluble In_2O_3 nanoparticles and In_2O_3–SnO_2 nanocomposites and their calcined thin films

Oil-soluble In2O3 nanoparticles and In2O3-SnO2 nanocomposites were prepared in oleylamine via decomposition of metal acety- lacetonate precursors. Thin films of In2O3 and In2O3-SnO2 were obtained by spin-coating solutions of the oil-soluble In2O3 nanoparticles and In2O3-SnO2 nanocomposites onto substrates and then calcining them. Transmission electron microspectroscopy, scanning electron mi- crospectroscopy, atomic force microspectroscopy, X-ray diffraction, ultraviolet-visible absorption, and photoluminescence spectroscopy were used to investigate the properties of the nanoparticles and thin films. The In2O3 nanoparticles were cubic-phased spheres with a diame- ter of-8 nm; their spectra exhibited a broad emission peak centered at 348 nm. The In2O3-SnO2 nanocomposites were co-particles composed of smaller In2O3 particles and larger SnO2 particles; their spectra exhibited a broad emission peak at 355 nm. After the In2O3-SnO2 nano- composites were calcined at 400℃, the obtained thin films were highly transparent and conductive, with a thickness of 30-40 nm; the sur- faces of the thin films were smooth and crack-free.

Preparation of High-Surface-Area SnO_2 and ZrO_2 by Reflux-Digestion and Solvothermal Methods

The influence of the preparation methods on the properties of SnO_2 and ZrO_2 powders,especially the specific surface area and the stability upon calcination was investigated.SnO_2 and ZrO_2 prepared by chemical precipitation using reflux-digestion process with NaOH possess high surface area at the calcination temperature of 500℃～1000℃.A novel solvothermal process in the presence of urea was used to synthesize nanocrystalline SnO_2 powders excluding the adulteration of Si.As increasing the concentration of urea,the grain size of the as-prepared powders reduced and the surface area increased. SnO_2 nanocrystals with a grain size of ca.1 nm and a high surface area of 331 m^2g^(-1) were obtained by this method.These high-surface-area powders are favorable for gas-sensing and catalysis applications,and the development of an advanced material for structural engineering ceramics.

Synthesis and Gas-sensing Performance of Nanosized SnO_2

Nanosized tin dioxide particles were prepared by sol-gel dialytic processes with tin(Ⅳ) chloride and alcohol as start materials. The nanoparticles of tin dioxide were charactered by thermogravimetry and differential thermal analysis(TG-DTA), X-ray diffraction(XRD), transmission electron microscopy (TEM) and BET. The results show that the average diameter of tin dioxide particles dried at 353 K was about 2 nm. Even if the tin dioxide particles were calcined at 873 K, the average diameter of particles was less than 10 nm. The removal of Cl- was solved by using this kind of method. The mechanism of the formation of tin dioxide nanosized particles was proposed and analyzed in this paper. We also measured the sensitivity of the sensor based on the tin oxide powder calcined at 673 K to NH 3, alcohol, acetone, hexane and CO. The gas-sensing performance results indicate that this sensor has a higher sensitivity to alcohol and acetone, and selectivity for NH 3, hexane and CO at an operating temperature of 343 K.

Spectroelectrochemical Investigation on Neutral Red

Neutral Red can be used as an indicator, a stain reagent or a mediator compound in the studies of biological redox systems. No reports dealing with the electrode process of Neutral Red, especially, about its kinetics have been published. In this paper we report the determinations of formal reduction potentials, the number of electrons transferred, diffusion coefficient as well as the rate constant of heterogeneous electron transfer

Multi-effect anthraquinone-based polyimide enclosed SnO_(2)/reduced graphene oxide composite as high-performance anode for lithium-ion battery

The cycling stability of SnO_(2)anode as lithium-ion battery is poor due to volume expansion.Polyimide coatings can effectively confine the expansion of SnO_(2).However,linear polyimides are easily dissolved in ester electrolytes and their carbonyls is not fully utilized during charging/discharging process.Herein,the SnO_(2)enclosed with anthraquinone-based polyimide/reduced graphene oxide composite was prepared by self-assembly.Carbonyls from the anthraquinone unit provide fully available active sites to react with Li^(+),improving the utilization of carbonyl in the polyimide.More exposed carbonyl active sites promote the conversion of Sn to SnO_(2)with electrode gradual activation,leading to an increase in reversible capacity during the charge/discharge cycle.In addition,the introduction of reduced graphene oxide cannot only improve the stability of polyimide in the electrolyte,but also build fast ion and electron transport channels for composite electrodes.Due to the multiple effects of anthraquinone-based polyimide and the synergistic effect of reducing graphene oxide,the composite anode exhibits a maximum reversible capacity of 1266 mAh·g^(−1) at 0.25 A·g^(−1),and maintains an excellent specific capacity of 983 mAh·g^(−1) after 200 cycles.This work provides a new strategy for the synergistic modification of SnO_(2).

Microstructure and properties of honeycomb composite films containing Eu and Sn

Honeycomb composite films were prepared by breath figure method via a straightforward,one-step process by doping complex containing Eu or Sn into polystyrene-b-poly(acrylic acid) solution.Several key influencing factors,such as the concentration of the block polymer solution,the relative humidity of the environment and the amount of complexes,were investigated to control micropore size and tune film surface properties.The characteristics of the composite films were studied by scanning electron microscopy(SEM),atomic force microscopy(AFM),X-ray diffraction(XRD),ultraviolet and emission spectra.Results indicate that composite films containing Eu have excellent optical performance,and micro-patterned bowl-like SnO_(2) microparticles could be fabricated from composite films containing Sn after being calcined at 600℃ for 5 h.This general approach for the fabrication of honeycomb composite films opens a convenient and effective route to the functional modification of honeycomb films and offers new prospects for the application in miniaturized sensors,micro-reactor and catalysis.

SnO_(2)修饰MoS_(2)薄膜的n-p可调室温氢气响应及其原位SKPM研究

研发高性能氢气传感器对氢能及相关产业发展具有重要意义.2D-MoS_(2)纳米材料在构建快速可靠的室温氢气传感器方面优势显著,但灵敏度和选择性较差.本文报导了具有n-p可调型氢敏响应行为的SnO_(2)修饰MoS_(2)薄膜,其原位SKPM研究表明SnO_(2)(0.38 eV)和MoS_(2)(0.26 eV)在氢敏响应中会出现不同的表面电势变化,使其界面势垒随SnO_(2)覆盖率的增加而改变,从而使界面效应对体系n型氢敏响应的积极贡献转变为负面补偿.当SnO_(2)覆盖率为6.4%时,传感器具有增敏、提速且选择性好的n型氢敏响应,当其提高至95.6%时呈现p型响应.这种随结构n-p可调的氢敏响应既能用于传感层的敏感性能调节,还可为MoS_(2)基二维材料的气敏响应类型调控提供简单易行、成本低廉的方法.

SnO_(2) quantum dots modified N-doped carbon as high-performance anode for lithium ion batteries by enhanced pseudocapacitance

SnO_(2) is considered to be a promising candidate as anode material for lithium ion batteries,due to its high theoretical specific capacity(1494 mAh·g^(-1)).Nevertheless,SnO_(2)-based anodes suffer from poor electronic conductivity and serious volume variation(300%)during lithiation/delithiation process,leading to fast capacity fading.To solve these problems,SnO_(2) quantum dots modified N-doped carbon spheres(SnO_(2) QDs@N-C)are fabricated by facile hydrolysis process of SnCl2,accompanied with the polymerization of polypyrrole(PPy),followed by a calcination method.When used as anodes for lithium ion batteries,SnO_(2) QDs@N-C exhibits high discharge capacity,superior rate properties as well as good cyclability.The carbon matrix completely encapsulates the SnO_(2) quantum dots,preventing the aggregation and volume change during cycling.Furthermore,the high N content produces abundant defects in carbon matrix.It is worth noting that SnO_(2) QDs@N-C shows excellent capacitive contribution properties,which may be due to the ultra-small size of SnO_(2) and high conductivity of the carbon matrix.

Synthesis of carbon-supported Pd/SnO_2 catalyst for highly selective hydrogenation of 2,4-difluoronitrobenzene

Halogenated anilines have a wide range of applications in the production of pharmaceuticals and agrochemical substances, and thus it is of great importance to develop highly active and selective catalysts for the hydrogenation of halogenated nitrobenzenes. We approach this challenge by probing noble metal/non-noble metal oxide nanoparticles（NPs） catalysts. Carbon-supported Pd/SnO2catalysts were synthesized by the chemical reduction method, and their catalytic activity was evaluated by the hydrogenation reaction of 2,4-difluoronitrobenzene（DFNB） to the corresponding 2,4-difluoroaniline（DFAN）, showing a remarkable synergistic effect of the Pd and SnO2 NPs. The as-prepared Pd/SnO2/C catalysts were characterized using TEM, XRD, H2 TPD and XPS techniques. Modifications to the electronic structure of the Pd atoms through the use of SnO2 led to the suppression of the hydrogenolysis of the C–F bond and the acceleration of nitrosobenzene（DFNSB） conversion and consequently, resulted in the inhibition of the formation of reactive by-products and may be responsible for the enhancements observed in selectivity.