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1.
Richard Kydd Wey Yang Teoh Kenneth Wong Yong Wang Jason Scott Qing‐Hua Zeng Ai‐Bing Yu Jin Zou Rose Amal 《Advanced functional materials》2009,19(3):369-377
Rapid synthesis of Cu? CeO2 catalysts by flame spray pyrolysis produces highly active Cu dimer morphologies without the need for additional catalyst pretreatment. The active Cu component is enriched onto the CeO2 surface at concentrations higher than the nominal loading with no evidence of amorphous or crystalline CuO phase. Increasing the Cu content results in a morphological transition from isolated Cu monomers to oxygen‐bridged dimers and an associated increase in oxygen vacancy concentration. Dimer‐containing Cu? CeO2 catalysts display high levels of activity and selectivity in the low‐temperature preferential oxidation of CO. Experimental measurements and simulations suggest that the geometry of the dimer presents a comparatively ionic Cu? O bond at the catalyst surface. Further studies indicate that these ionic dimer species promote preferential CO oxidation at lower temperatures than observed for monomeric Cu species. This is the first report to explicitly propose and demonstrate that the structural distortion associated with the formation of Cu dimers directly induces increased bond ionicity at the catalyst surface and that these changes are responsible for improved catalytic activity. 相似文献
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Nanocrystalline β-In2S3 thin films were grown using the chemical spray pyrolysis technique. Conductive AFM studies showed the presence of a conduction path through the core of the nano-crystallites which showed higher conductivity (an order) compared to the conduction path through the grain boundaries. The conduction path through the grain boundary material exhibited higher conductivity (2 orders) compared to the grain. The local current–voltage measurements carried out at the grain boundaries encapsulating the crystallites exhibited rectification behavior. The nano-crystalline thin films with conducting core showed persistent photoconductivity even when exposed to very low levels of light intensity. The persistent photoconductivity has been modeled based on the conducting core, insulating grain and conducting grain boundary identified in these thin films. 相似文献
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Meng-Meng Wang Jun-Jie Cai Hui-Jie Lun Ming-Guang Lv Jing-Qi Zhang Swetha Andra Beibei Li Dong-Bin Dang Yan Bai Ya-Min Li 《Advanced functional materials》2024,34(7):2311912
The “visible” proton-conducting pathway offers a distinct advantage for researching the mechanism of proton conducting materials at the molecular level and developing new materials. To achieve this, three crystalline materials are constructed via acid–base chemistry based on phosphomolybdic acid and diversfied guanidine, namely, (CN3H6)6(PMo12O40)2·H2O (GH–PMo12), (CN4H7)3(PMo12O40)·H2O (AGH–PMo12), and (CN5H8)3(PMo12O40)·3.5H2O (DAGH–PMo12). Proton conductivity of GH–PMo12 in the [001] direction reaches up to 0.19 S cm−1 at 85 °C and 98% RH, as elucidated by impedance studies of single crystals. The clear proton transport path is proposed through the analysis of single crystal structure. Moreover, impedance studies of powder crystals reveal that the proton conductivity of GH–PMo12 is higher than that of the other two compounds. The underlying reasons for this result are clarified through the analysis of the pKa, proton density, and spatial structure. Additionally, GH–PMo12 is fabricated into composite membrane with a peak proton conductivity of 5.31 × 10−2 S cm−1, which exhibits promising potential for real-world applications. 相似文献
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Ivan Isakov Hendrik Faber Max Grell Gwenhivir Wyatt‐Moon Nikos Pliatsikas Thomas Kehagias George P. Dimitrakopulos Panos P. Patsalas Ruipeng Li Thomas D. Anthopoulos 《Advanced functional materials》2017,27(22)
The growth mechanism of indium oxide (In2O3) layers processed via spray pyrolysis of an aqueous precursor solution in the temperature range of 100–300 °C and the impact on their electron transporting properties are studied. Analysis of the droplet impingement sites on the substrate's surface as a function of its temperature reveals that Leidenfrost effect dominated boiling plays a crucial role in the growth of smooth, continuous, and highly crystalline In2O3 layers via a vapor phase‐like process. By careful optimization of the precursor formulation, deposition conditions, and choice of substrate, this effect is exploited and ultrathin and exceptionally smooth layers of In2O3 are grown over large area substrates at temperatures as low as 252 °C. Thin‐film transistors (TFTs) fabricated using these optimized In2O3 layers exhibit superior electron transport characteristics with the electron mobility reaching up to 40 cm2 V?1 s?1, a value amongst the highest reported to date for solution‐processed In2O3 TFTs. The present work contributes enormously to the basic understanding of spray pyrolysis and highlights its tremendous potential for large‐volume manufacturing of high‐performance metal oxide thin‐film transistor electronics. 相似文献
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Liyu Zhu Yucheng Li Peng Ye Jingyang Zhao Jing Liu Jiandu Lei Luying Wang Ruisheng Xue 《Advanced functional materials》2023,33(10):2210453
Proton exchange membranes (PEMs) that can heal mechanical damage to restore original functions are imperative for fabricating reliable and durable proton exchange membrane fuel cells (PEMFCs). Here, an ultra-stable, highly proton conductive self-healing PEM via hydrogen-bonding complexation between Nafion and poly(vinyl alcohol) (PVA) followed by incorporation of sodium lignosulfonate (SLS) intercalation-modified graphene oxide (GO) and post-modification with 4-formylbenzoic acid (FBA) is presented. Notably, the introduction of GO complexes and post-modification of FBA molecules effectively improves the stability of composite membranes and also participate in the establishment of proton-conducting nanochannels. Compared with recast Nafion, the FBA-Nafion/PVA@SLS/GO composite membranes exhibit enhanced mechanical properties (36.2 MPa at 104.8% strain) and higher proton conductivity (0.219 S cm−1 at 80 °C-100% RH and 23.861 mS cm−1 at 80 °C-33% RH, respectively). More importantly, the incorporated PVA gives the FBA-Nafion/PVA@SLS/GO composite membranes superior self-healing capabilities that can heal mechanical damage of several tens of micrometers in size and restore their original proton conductivity under the operating conditions of the PEMFCs. This study opens an avenue toward the development of reliable and durable PEM for PEMFCs. 相似文献
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Fe-doped ZnO thin films have been prepared by spray pyrolysis on glass substrates and the influence of Fe-doping concentration on the structural and optical properties of the films has been studied.The X-ray diffraction (XRD) analysis shows that Fe doping has a significant effect on crystalline quality,grain size and strain in the thin films.The best crystalline structure is obtained for 3 at%Fe doping as observed from scanning electron microscopy (SEM) and XRD.However,lower or higher Fe-doping degrades the crystalline quality in turn.Moreover,UV spectroscopy demonstrates the influence of Fe-incorporation on visible range transmittance of ZnO where the best transmittance is obtained for 3 at%doping.The results have been illustrated simultaneously focusing previous results obtained from literature. 相似文献
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Jennifer L. M. Rupp Barbara Scherrer Ashley S. Harvey Ludwig J. Gauckler 《Advanced functional materials》2009,19(17):2790-2799
The introductory part reviews the impact of thin film fabrication, precipitation versus vacuum‐based methods, on the initial defect state of the material and microstructure evolution to amorphous, biphasic amorphous‐nanocrystalline, and fully nanocrystalline metal oxides. In this study, general rules for the kinetics of nucleation, crystallization, and grain growth of a pure single‐phase metal oxide thin film made by a precipitation‐based technique from a precursor with one single organic solvent are discussed. For this a complete case study on the isothermal and non‐isothermal microstructure evolution of dense amorphous ceria thin films fabricated by spray pyrolysis is conducted. A general model is established and comparison of these thin film microstructure evolution to kinetics of classical glass‐ceramics or metallic glasses is presented. Knowledge on thermal microstructure evolution of originally amorphous precipitation‐based metal oxide thin films allows for their introduction and distinctive microstructure engineering in devices‐based on microelectromechanical (MEMS) technology such as solar cells, capacitors, sensors, micro‐solid oxide fuel cells, or oxygen separation membranes on Si‐chips. 相似文献
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Highly transparent conductive stoichiometric nanocrystalline stannic oxide coatings were deposited onto Corning?EAGLE XG?slim glass substrates.Including each coating,it was deposited for various concentrations in the aerosol solution with the substrate temperature maintained at 623.15 K by an ultrasonic spray pyrolysis(USP)technique.Nitrogen was em-ployed both as the solution carrier in addition to aerosol directing gas,maintaining its flow rates at 3500.0 and 500.0 mL/min,respectively.The coatings were polycrystalline,with preferential growth along the stannic oxide(112)plane,irrespective of the molarity content in the spray solution.The coating prepared at 0.2 M,a concentration in the aerosol solution,showed an average transmission of 60%in the visible light region spectrum with a maximum conductivity of 24.86 S/cm.The coatings deposited exhibited in the general photoluminescence spectrum emission colors of green,greenish white,and bluish white calculated on the intensities of the excitonic and oxygen vacancy defect level emissions. 相似文献
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Cu2ZnSnS4 (CZTS)/ZnS heterojunctions have been prepared by a successive deposition of ZnS and CZTS thin films by ultrasonic spray pyrolysis technique on glass substrates. The cupric chloride concentration has been varied in the starting solution in order to investigate its influence on device properties. CZTS/ZnS heterojunctions were characterized by recording their current-voltage characteristics at different temperatures. The obtained results exhibit a good rectifying behavior of the realized heterojunction. Analysis of these results yields saturation current, series resistance and ideality factor determination. From the activation energy of saturation current we inferred that the thermal emission through the barrier height is the dominant mechanism of the reverse current rather than the defects contribution. 相似文献
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A series of ZnO-CdO thin films of different molar ratios of Zn and Cd have been deposited on glass substrate at substrate temperature ~ 360 ℃ by the spray pyrolysis technique at an ambient atmosphere. X-ray diffraction (XRD) studies confirmed the polycrystalline nature of the film and modulated crystal structures of wurtzite (ZnO) and cubic (CdO) are formed. The evaluated lattice parameters, and crystallite size are consistent with literature. Dislocation density and strain increased in the film as the grain sizes of ZnO and CdO are decreased. The band gap energy varies from 3.20 to 2.21 eV depending on the Zn/Cd ratios in the film. An incident photon intensity dependent I-V study confirmed that the films are highly photosensitive. Current increased with the increase of the intensity of the light beam. The optical conductivity and the optical constants, such as extinction coefficient, refractive index and complex dielectric constants are evaluated from transmittance and reflectance spectra of the films and these parameters are found to be sensitive to photon energy and displayed intermediate optical properties between ZnO and CdO, making it preferable for applications as the buffer and window layers in solar cells. 相似文献
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The electrical conductivity of ceria thin films (epitaxial as well as dense and porous nanocrystalline) is investigated in dry and wet atmosphere at temperatures below 500 °C. For the epitaxial and the fully dense nanocrystalline samples, no significant differences can be observed between dry and wet conditions. In marked contrast, the nanocrystalline porous films obtained via spin coating exhibit a considerable enhancement of the protonic conductivity below 300 °C in wet atmosphere. This outcome reveals that the residual open mesoporosity plays the key role for the enhancement of the proton transport at low temperatures and not the high density of grain boundaries. The quantitative analysis of the various pathways, along which the proton transport can take place, indicates that the observed proton conduction can arise not only from bulk water adsorbed in the open pores but also from the space charge zones on the water side of the water/oxide interface. 相似文献
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Zn Se thin films are successfully deposited by spray pyrolysis deposition technique.Deposited thin films are characterized by X-ray diffraction study,and it reveals that spray-deposited Zn Se thin films are polycrystalline with hexagonal crystal structure.Surface morphology is carried out by scanning electron microscopy.It shows cotton-like morphology,and optical properties,such as absorbance,transmittance,reflectance,band gap,refractive index,extinction coefficient are studied.Photoluminescence shows strong emission at 497 nm.Also,spraydeposited Zn Se thin films are hydrophilic in nature,which is shown by contact angle meter. 相似文献
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Liyu Zhu Limei Zhang Yuting Ren Jiandu Lei Luying Wang Jing Liu 《Advanced functional materials》2024,34(17):2313844
Achieving rapid ion transport through nanochannels is essential for both biological and artificial membrane systems. Covalent organic frameworks (COFs) with well-defined nanostructures hold great promise for addressing the above challenge. However, due to the limited processability and inadequate interlamellar interaction of COF materials, it is extremely difficult to integrate them to prepare high-performance proton conductors. Herein, inspired by the ingenious bio-adhesion strategy in nature, ultrafast proton conduction is achieved by taking advantage of COF membranes where TP-COF nanosheets are linked by subnanometer nanowires/lignocellulosic nanofibrils composites (SNWs/LCNFs) through electrostatic and π-π interactions to form an ordered and robust structure. Notably, the synthesized SNWs exhibited impressive proton conductivity and adhesion capacity due to their inbuilt phosphotungstic acid (HPW) molecules and multidimensional interactions. Therefore, attributed to the synergistic contribution of TP-COFs and SNWs, the composite membrane achieves ultrahigh proton conductivity (0.395 S cm−1 at 80 °C and 100% RH), superior mechanical property (109.8 MPa), exceptional fuel cell performance (71.6 mW cm−2), and superior operational stability (OCV decay rate is about 1.5 mV h−1), demonstrating outstanding competitiveness. More importantly, the proposed design concept has the potential to be applied in membranes for various electrochemical devices and molecular separations. 相似文献
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Indium sulfide (In2S3) thin films are of interest as buffer layers in chalcopyrite absorber based solar cells; and as media providing two-photon absorption for intermediate-band solar cells. We investigated the suitability of chemical spray pyrolysis (CSP) for growing In2S3 thin films in a structural order where indium atoms are preferentially in the octahedral sites. We sprayed aqueous or alcoholic solutions of indium chloride (InCl3) and thiourea (SC(NH2)2) precursors onto a substrate with surface temperatures (TS) of 205, 230, 275 and 320 °C. The as-deposited films grown from aqueous solutions were annealed in 5% H2S containing atmosphere at 500 °C. We used Raman spectroscopy, X-ray diffraction and Energy Dispersive X-ray spectroscopy to evaluate the effect of growth temperature and the effect of annealing on the film structure and stoichiometry. The use of alcoholic solvent instead of aqueous allows us to use much lower TS while preserving the quality of the β-In2S3 films obtained. Similarly, films with increased stoichiometry and quality are present at a higher TS; and when annealed. The annealing of the films grown at TS of 205 °C results in a much higher gain of the crystal quality compared to the gain when annealing the films grown at TS of 320 °C, although the quality remain higher when deposited at TS of 320 °C. Simultaneously with the increase of the film quality, there is a sign of increased quality of the crystal ordering with indium in the octahedral sites. Such a crystal ordering favor the use of CSP deposited In2S3 films in the intermediate band solar cells. 相似文献
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在空气中采用喷雾热解法合成了稀土铕(Eu)、铽(Tb)及铥(Tm)掺杂的铝酸锌(ZnAl_2O_4)发光膜,研究了合成条件对其阴极射线发光特性的影响。ZnAl_2O_4:Tb~(31)、ZnAl_2O_4:Tm~(3 )及ZnAl_2O_4:Eu~(31)膜分别发出主峰位于555 nm的绿光、主峰位于478 nm的蓝光及主峰位于616 nm的红光。上述发光均可在低退火温度(700℃以下)下获得,因此可以使用玻璃作为基底。同时研究了样品发光的色坐标和色纯度,并与标准的红、绿、蓝粉的色品度进行了比较。样品的亮度和效率都随外加电压的增加而增大,没有观察到亮度饱和现象。此外,Eu掺杂的ZnAl_2O_4膜在850℃以上、还原气氛中退火后呈现Eu~(2 )的特征发射——宽的蓝发射带。 相似文献
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M. R. Fadavieslam N. Shahtahmasebi M. Rezaee-Roknabadi M. M. Bagheri-Mohagheghi 《半导体学报》2011,32(11):113002-8
Tin sulfide thin films (SnxSy) with an atomic ratio of y/x = 0.5 have been deposited on a glass substrate by spray pyrolysis. The effects of deposition parameters, such as spray solution rate (R), substrate temperature (Ts) and film thickness (t), on the structural, optical, thermo-electrical and photoconductivity related properties of the films have been studied. The precursor solution was prepared by dissolving tin chloride (SnCl4, 5H2O) and thiourea in propanol, and SnxSy thin film was prepared with a mole ratio of y/x = 0.5. The prepared films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. It is indicated that the XRD patterns of SnxSx films have amorphous and polycrystalline structures and the size of the grains has been changed from 7 to 16 nm. The optical gap of SnxSx thin films is determined to be about 2.41 to 3.08 eV by a plot of the variation of (αhν)2 versus hν related to the change of deposition conditions. The thermoelectric and photo-conductivity measurement results for the films show that these properties are depend considerably on the deposition parameters. 相似文献
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N. H. Beltrán C. Balocchi X. Errazu R. E. Avila G. Piderit 《Journal of Electronic Materials》1998,27(2):L9-L11
Zirconia (8 mol% yttria) (YSZ) amorphous layers were deposited by spray pyrolysis on Si oxidized substrates and crystallized
by rapid thermal treatment in a home-made halogen lamps furnace. Uniform films were obtained by depositing up to six layers,
followed by the thermal treatment. X-ray analysis showed that the cubic phase is obtained during the initial stage of the
annealing process. No significant differences with increasing annealing time nor interaction between the YSZ film and the
substrate were observed. Ionic conduction in air, with activation energies comparable to those of bulk YSZ ceramics, was observed.
The electrical characteristics of the films make them suitable for microelectronics applications. 相似文献