共查询到20条相似文献,搜索用时 15 毫秒
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Dr. Tetsuo Tsuchiya Dr. Tomohiko Nakajima Yuko Uzawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(42):9261-9276
This review summarizes the use of photoreactions that replace conventional heating processes for growing oxide thin films from chemical solutions. In particular, this review outlines key variables in photoreactions that affect epitaxial and polycrystalline thin film growth, including precursor materials, laser wavelength, laser fluence, and carbon. In addition, the features of the photoreaction process that can be controlled at a low temperature by oxygen non-stoichiometry are examined. Likewise, functions that are neither achieved by developing a gradient structure nor controlled by a thermal equilibrium reaction are detailed. Two new concepts are presented, known as photoreaction of nanoparticles (PRNP) and photoreaction of a hybrid solutions (PRHS), in which crystal nuclei are pre-dispersed in a metal–organic compound film. This method has successfully produced flexible phosphor films used as resistor or thermistor electronic components. Finally, thin film growth using different light sources such as flash lamps and femtosecond lasers (fs) is explored. 相似文献
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Enhancing Hematite Photoanode Activity for Water Oxidation by Incorporation of Reduced Graphene Oxide
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Saulo do Amaral Carminati Prof. Flavio L. Souza Prof. Ana F. Nogueira 《Chemphyschem》2016,17(1):170-177
Two effective methods to prepare reduced graphene oxide (rGO)/hematite nanostructured photoanodes and their photoelectrochemical characterization towards water splitting reactions are presented. First, graphene oxide (GO) is reduced to rGO using hydrazine in a basic solution containing tetrabutylammonium hydroxide (TBAOH), and then deposited over the nanostructured hematite photoanodes previously treated at 750 °C for 30 min. The second method follows the deposition of a paste containing a mixture of hematite nanoparticles and rGO sheets by the doctor‐blade method, varying the rGO concentration. Since hematite suffers from low electron mobility, a low absorption coefficient, high recombination rates and slow reaction kinetics, the incorporation of rGO in the hematite can overcome such limitations due to graphene's exceptional properties. Using the first method, the rGO incorporation results in a photocurrent density increase from 0.56 to 0.82 mA cm?2 at 1.23 VRHE. Our results indicate that the rGO incorporation in the hematite photoanodes shows a positive effect in the reduction of the electron–hole recombination rate. 相似文献
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Riyazuddin Samrin Bano Fohad Mabood Husain Jamal Akhter Siddique Khadijah H. Alharbi Rais Ahmad Khan Ali Alsalme 《Molecules (Basel, Switzerland)》2020,25(24)
Epoxy resins (EP) have been used as a thermos-setting material in the field of coating, casting, bonding agent, and laminating. However, a major drawback associated with its use is the lack of good flaming properties, and it is responsible for heavy smoke along with hazardous gases considerably limiting its uses in various fields. In this study, N-ethanolamine triazine-piperizine, a melamine polymer (ETPMP), was established as a new charring-foaming agent and was successfully synthesized with ethanolamine, piperizine, cyanuric chloride, and melamine as precursor molecules via the nucleophilic substitution reaction method. Elemental analysis and Fourier transform infrared (FTIR) spectroscopy analysis were applied to approve the synthesis of ETPMP and confirmation of its structure and characterization. The epoxy coating of intumescent flame retardant (IFR) was equipped by introducing ETPMP, ammonium polyphosphate (APP), and copper oxide (CuO) in multiple composition ratios. CuO was loaded at various amounts into the IFR-coating system as a synergistic agent. The synergistic action of CuO on IFR coatings was scientifically examined by using different analytical tests such as vertical burning test (UL-94V), limited oxygen index (LOI), thermal gravimetric analysis (TGA), cone calorimeter, and scanning electron microscope (SEM). The results showed that small changes in the amount of CuO expressively amplified the LOI results and enhanced the V-0 ratings in the UL-94V test. The TGA data clearly demonstrate that the inclusion of CuO can transform the thermal deprivation behavior of coatings with a growing char slag proportion with elevated temperatures. Information from cone calorimeter data affirmed that CuO can decrease the burning factors by total heat release (THR) together with peak heat release rate (PHRR). The SEM images indicated that CuO can enrich the power and compression of the intumescent char that restricts the movement of heat and oxygen. Our results demonstrate a positive influence of CuO on the epoxy-headed intumescent flame retardant coatings. 相似文献
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Carbon Monoxide Oxidation on Metal‐Supported Monolayer Oxide Films: Establishing Which Interface is Active
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Dr. Ke Zhang Dr. Linfei Li Dr. Shamil Shaikhutdinov Prof. Dr. Hans‐Joachim Freund 《Angewandte Chemie (International ed. in English)》2018,57(5):1261-1265
Ultrathin (monolayer) films of transition metal oxides grown on metal substrates have recently received considerable attention as promising catalytic materials, in particular for low‐temperature CO oxidation. The reaction rate on such systems often increases when the film only partially covers the support, and the effect is commonly attributed to the formation of active sites at the metal/oxide boundary. By studying the structure and reactivity of FeO(111) films on Pt(111), it is shown that, independent of the film coverage, CO oxidation takes place at the interface between reduced and oxidized phases in the oxide film formed under reaction conditions. The promotional role of a metal support is to ease formation of the reduced phase by reaction between CO adsorbed on metal and oxygen at the oxide island edge. 相似文献
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A. S. Bhattacharyya S. K. Raj Parameshwar Kommu P. Prabhakar R. Praveen Kumar Neha Kumari Kumar Gaurav 《Surface and interface analysis : SIA》2016,48(12):1294-1298
Cu thin films were deposited on Si(111), glass, and quartz substrates by magnetron sputtering. X‐ray diffraction, SEM, and photoemission electron microscope studies were carried out to characterize the films. An influence of the nature of substrate on the Cu2O and CuO phases formed was observed. Copper silicide formation in case of silicon substrates aided in formation of Cu2O rather than CuO unlike glass and quartz substrates. Formation of nanocrystallites was observed by SEM and X‐ray diffraction. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Transition metal (Mn, Fe, Co, Ni, Cu) oxide was formed in LSM-YSZ cathode by nitrate solution infiltration method. LSM-YSZ/YSZ/LSM-YSZ symmetric cell performance at intermediate temperature range 600~800 ℃ was studied by electrochemical impedance spectroscopy (EIS). EIS test results showed that the polarization resistances of LSM-YSZ with metal oxide infiltration were much lower than that without metal oxide infiltration, 60%~80% polarization resistance decrease was reached by metal nitrate solution infiltration. The activation energy of oxygen reduction reaction derived from polarization resistance showed that the performance of LSM-YSZ with different metal oxide infiltration has different activation energy decrease, Co nitrate infiltration showed the biggest activation energy decrease. Mn, Fe and Cu nitrate solution infiltrated LSM-YSZ showed good polarization resistance decrease at the tested temperature range. 相似文献
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硝酸盐制备三维有序大孔金属氧化物材料研究 总被引:2,自引:0,他引:2
用硝酸盐、柠檬酸和乙醇/水按一定摩尔比配置成前驱物溶液, 采用胶晶模板法, 制备了三维有序大孔金属氧化物材料: Al2O3, CeO2, Cr2O3, NiO, MgO, In2O3, CeO2/Al2O3, Cr2O3/Al2O3和NiO/Al2O3. SEM观察表明, 材料中大孔有序排列, 大孔间由小孔相连, 形成三维规则的笼状网络结构. XRD和TEM测试表明, 大孔孔壁由具有纳米尺寸的金属氧化物粒子组成. 实验表明, 加入乙醇、柠檬酸, 提高溶液对胶球润湿性, 改善溶液渗透能力, 避免粒子团聚, 有利于有序大孔结构的形成. 这一研究表明, 根据硝酸盐的物理化学性质, 调整溶液组成, 选择合适的热处理温度, 能得到大孔排列有序、三维规整性好的大孔结构材料. 此法具有原料易得, 操作简单的特点, 是3DOM材料的一种新型高效制备路线. 相似文献
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还原态氧化石墨烯的制备及其对重金属离子的吸附性能 总被引:2,自引:1,他引:1
通过乙二胺(EDA)对氧化石墨烯(GO)进行还原制备了还原态氧化石墨烯(RGO),利用红外光谱、拉曼光谱、热重分析和扫描电子显微镜等技术对制得的RGO进行了表征。 考察了RGO复合材料在静态吸附条件下对Pb(Ⅱ)、Cd(Ⅱ)、Cu(Ⅱ)和Mn(Ⅱ)金属离子的吸附性能。 结果表明,该吸附材料对上述4种重金属离子在25 ℃时的静态饱和吸附量分别为396.6、115.3、54.2和38.6 mg/g。 吸附于RGO上的Pb(Ⅱ)可用0.05 mol/L HCl溶液进行洗脱,再生后的RGO重复使用3次时吸附量能达到首次吸附量的85%。 相似文献
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Dr. David López‐Díaz Prof. Maria Mercedes Velázquez Santiago Blanco de La Torre Ana Pérez‐Pisonero Prof. Raquel Trujillano Prof. José Luis García Fierro Sergi Claramunt Prof. Albert Cirera 《Chemphyschem》2013,14(17):4002-4009
We study the effect of oxidative impurities on the properties of graphene oxide and on the graphene oxide Langmuir–Blodgett films (LB). The starting material was grupo Antolín nanofibers (GANF) and the oxidation process was a modified Hummers method to obtain highly oxidized graphene oxide. The purification procedure reported in this work eliminated oxidative impurities decreasing the thickness of the nanoplatelets. The purified material thus obtained presents an oxidation degree similar to that achieved by chemical reduction of the graphite oxide. The purified and non‐purified graphene oxides were deposited onto silicon by means of a Langmuir–Blodgett (LB) methodology. The morphology of the LB films was analyzed by field emission scanning microscopy (FE‐SEM) and micro‐Raman spectroscopy. Our results show that the LB films built by transferring Langmuir monolayers at the liquid‐expanded state of the purified material are constituted by close‐packed and non‐overlapped nanoplatelets. The isotherms of the Langmuir monolayer precursor of the LB films were interpreted according to the Volmer’s model. 相似文献
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Effect of Calcium Oxide Additive on the Performance of Iron Oxide Sorbent for High-Temperature Coal Gas Desulfurization
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Huiling Fan Kechang Xie Ju Shangguan Fang Shen Chunhu Li Key Laboratory for Coal Science Technology of Ministry of Education Shanxi Province Taiyuan University of Technology Taiyuan Shanxi China 《天然气化学杂志》2007,16(4)
The effect of calcium oxide additive in iron oxide sorbent for hot gas desulfurization was investigated by XRD and TPR techniques.XRD characterization showed that CaO was highly dispersed after the calcination of sorbents.Calcium sulfate formed in the desulfurization was decomposed and regenerated to CaO by reacting with CO before the next sulfidation process.Calcium participated in every sulfidation/regeneration cycle and contributed to the enhancement of sulfur capacity.The TPR results showed that the reduction temperature of the sorbent increased with the increase of the content of calcium.Calcium played a role of retarding reduction.Therefore,the addition of calcium oxide additive will benefit the utilization of iron oxide sorbent in strongly reducing atmospheres. 相似文献
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Effect of Calcium Oxide Additive on Sorbent for High-Temperature the Performance of Iron Oxide Coal Gas Desulfurization 总被引:1,自引:0,他引:1
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Huiling Fan Kechang Xie Ju Shangguan Fang Shen Chunhu Li 《天然气化学杂志》2007,16(4):404-408
The effect of calcium oxide additive in iron oxide sorbent for hot gas desulfurization was investigated by XRD and TPR techniques. XRD characterization showed that CaO was highly dispersed after the calcination of sorbents. Calcium sulfate formed in the desulfurization was decomposed and regenerated to CaO by reacting with CO before the next sulfidation process. Calcium participated in every sulfidation/regeneration cycle and contributed to the enhancement of sulfur capacity. The TPR results showed that the reduction temperature of the sorbent increased with the increase of the content of calcium. Calcium played a role of retarding reduction. Therefore, the addition of calcium oxide additive will benefit the utilization of iron oxide sorbent in strongly reducing atmospheres. 相似文献
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Alexandra Inayat Ayman Makky Jose Giraldo Andreas Kuhnt Corinna Busse Prof. Dr. Wilhelm Schwieger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(26):8161-8169
An in situ method for the growth of ZnO nanocrystals on Zn/Al mixed metal oxide (MMO) surfaces is presented. The key to this method is the thermal treatment of Zn/Al layered double hydroxides (Zn/Al LDHs) in the presence of nitrate anions, which results in partial demixing of the LDH/MMO structure and the subsequent crystallization of ZnO crystals on the surface of the forming MMO layers. In a first experimental series, thermal treatment of Zn/Al LDHs with different fractions of nitrate and carbonate in the interlayer space was examined by thermogravimetry coupled with mass spectrometry (TG‐MS) and in situ XRD. In a second experimental series, Zn/Al LDHs with only carbonate in the interlayer space were thermally treated in the presence of different amounts of an external nitrate source (NH4NO3). All obtained Zn/Al MMO samples were analysed by electron microscopy, nitrogen physisorption and powder X‐ray diffraction. The gas phase formed during nitrate decomposition turned out to be responsible for the formation of crystalline ZnO nanoparticles. Accordingly, both interlayer nitrate and the presence of ammonium nitrate led to the formation of supported ZnO nanocrystals with mean diameters between 100 and 400 nm, and both methods offer the possibility to tailor the amount and size of the ZnO crystals by means of the amount of nitrate. 相似文献
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Dr. Iñigo Bretos Dr. Ricardo Jiménez Dr. Jesús Ricote Prof. M. Lourdes Calzada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(42):9277-9291
Photochemistry has emerged in the last few years as a powerful tool for the low-temperature processing of metal oxide thin films prepared by solution methods. Today, its implementation into the fabrication procedure makes possible the integration of amorphous semiconductors or functional crystalline oxides into flexible electronic systems at temperatures below 350 °C. In this review, the effects of UV irradiation at the different stages of the chemical solution deposition of metal oxide thin films are presented. These stages include from the synthesis of the precursor solution to the formation of the amorphous metal-oxygen network in the film and its subsequent crystallization into the oxide phase. Photochemical reactions that can be induced in both the solution deposited layer and the irradiation atmosphere are first described, highlighting the role of the potential reactive chemical species formed in the system under irradiation, such as free radicals or oxidizing compounds. Then, the photochemical effects of continuous UV light on the film are shown, focusing on the decomposition of the metal precursors, the condensation and densification of the metal-oxygen network, and the nucleation and growth of the crystalline oxide. All these processes are demonstrated to advance the formation and crystallization of the metal oxide thin film to an earlier stage, which is ultimately translated into a lower temperature range of fabrication. The reduced energy consumption of the process upon decreasing the processing temperature, and the prospect of using light instead of heat in the synthesis of inorganic materials, make photochemistry as a promising technique for a sustainable future ever more needed in our life. 相似文献
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An alkaline mixture containing copper(II) spices, graphene oxide and glucose was heated by far infrared radiations to synthesize graphene-cuprous oxide hybrid. The hybrid was blended with mineral oil and packed into tubes to fabricate paste electrodes. The electrodes were coupled with capillary electrophoresis for the detection of polyhydroxy compounds. The sensitivities of them on the hybrid electrodes were significantly enhanced by taking advantages of graphene and cuprous oxide. The contents of polyhydroxy compounds in tobacco method was determined by the electrodes with satisfactory assay results. 相似文献
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金属氧化物薄膜如HfO2(被称为高k电介质)是现代微电子器件的关键组件,广泛用于计算机(平板电脑,笔记本电脑和台式机)、智能电话、智能电视、汽车和医疗设备中。具有大介电常数(k)的金属氧化物已经取代了介电常数小的SiO2(k=3.9),从而使得微电子元件进一步小型化。过渡金属化合物在化学气相沉积(CVD)和原子层沉积(ALD)中被广泛用作前体,通过与O2、H2O或O3的反应生成金属氧化物薄膜。微电子金属氧化物膜是纳米材料最广泛应用的一个领域。本文概观该领域的最新进展,包括我们对d0过渡金属配合物与O2反应的研究。 相似文献
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Stephan Enthaler Bernhard Hagemann Giulia Erre Kathrin Junge Matthias Beller 《化学:亚洲杂志》2006,1(4):598-604
Iron complexes generated in situ catalyze homogeneously the transfer hydrogenation of aliphatic and aromatic ketones by utilizing 2‐propanol as a hydrogen donor in the presence of base. The influence of different reaction parameters on the catalytic activity is investigated in detail by applying a three‐component catalyst system composed of an iron salt, 2,2′:6′,2′′‐terpyridine, and PPh3. The scope and limitations of the described catalyst is shown in the reduction of 11 different ketones. In most cases, high conversion and excellent chemoselectivity are obtained. Mechanistic studies indicate a monohydride reaction pathway for the homogeneous iron catalyst. 相似文献