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Microstructure and variable emittance property of annealed La-Sr-Mn-O films

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Journal of Rare Earths 2011年第1期29卷 83-86页

作者：江少群马欣新唐光泽王泽华王刚周泽华 College of Mechanics and Materials Hohai University School of Materials Science and Engineering Harbin Institute of Technology

The La-Sr-Mn-O films were deposited on Si（100） substrates by DC magnetron sputtering and followed by air annealing at 973 K for I h. The microstructure and temperature dependence of total hemispherical emittance （εH） of the annealed La-Sr-Mn-O films prepared at various processing parameters were investigated. The results indicated the films deposited at lower sputtering pressure and lower O2（O2＋Ar） volume proportion （R0） were present in rhombohedral .perovskite structure and the length of MnO bond was shorter. The metal-insulator transition temperature （TMI） was higher. All of the annealed films showed the unique feature of variable emittance based on metal-insulator transition. The films showed low emittance at low temperature but high emittance at high temperature. Moreover, the εH significantly changed in the vicinity of TMI. The variability of total hemispherical emittance （△ε） and the temperature range with obvious emittance change could be adjusted by changing the processing parameters. The Aε could be 0.45 and △ε/ε355 （ε355 is the εH at 355K） exceeded 50% for the annealed La-Sr-Mn-O films. Therefore, the annealed La-Sr-Mn-O films showed much potential for thermal control applications as smart thermochromic variable emittance materials.

关键词： manganese oxide thin film thermal control variable emittance metal-insulator transition rare earths

Fabrication and electrochemical performance of nanofibrous micro-frameworks of α-MnO_2

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Particuology 2014年第6期12卷 54-58页

作者： Dalai Jin Ruirui Liu Xiaochu Ding Longcheng Wang Lina Wang Linhai Yue Center of Materials Engineering Zhejiang Sci-Tech University Department of Chemistry Zhejiang University Department of Chemistry Michigan Technological University1400 Townsend DriveMI 49931USA Key Laboratory of Advanced Textile Materials and Manufacturing Technology Ministry of EducationZhejiang Sci-Tech University

A facile solid-phase conversion route is proposed to fabricate a micro-framework of α-MnO2 with a nanofibrous structure and high porosity.The fabrication is achieved by a three-step process using a preformed manganese tartrate with a rectangular framework as the precursor followed by thermal annealing and hydrothermal oxidation to form the final nanofibrous structure.Evolution of the phase and the morphology are characterized by FESEM,XRD,TG-DTA,and TEM measurements.The electrochemically active material α-MnO2 exhibits both attractive stability of the Coulombic efficiency after long-term cyclic charging/discharging and acceptable specific capacitance.

关键词： manganese oxide Hierarchical structure Nanofiber

A review of cadmium sorption mechanisms on soil mineral surfaces revealed from synchrotron-based X-ray absorption fine structure spectroscopy:Implications for soil remediation

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Pedosphere 2021年第1期31卷 11-27页

作者： Xinxin MO Matthew G.SIEBECKER Wenxian GOU Ling LI Wei LI Key Laboratory of Surficial Geochemistry Ministry of EducationSchool of Earth Sciences and EngineeringNanjing UniversityNanjing 210023China Department of Plant and Soil Science Texas Tech UniversityLubbock TX 79409(USA) State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China

The sorption of cadmium(Cd) is one of the most important chemical processes in soil, affecting its fate and mobility in both soil and water and ultimately controlling its bioavailability. In order to fundamentally understand the sorption/desorption of Cd in soil systems, X-ray absorption fine structure spectroscopy(XAFS) has been applied in numerous studies to provide molecular-level information that can be used to characterize the surface adsorption and precipitation reactions that Cd can undergo. This information greatly improves our current knowledge of the possible chemical reactions of Cd in soil. This paper critically reviews the mechanisms of Cd sorption/desorption at the mineral-water interface based on XAFS studies performed over the past twenty years. An introduction to the basic concepts of sorption processes is provided, followed by a detailed interpretation of XAFS theory and experimental data collection and processing,ending finally with a discussion of the atomic/molecular-scale Cd sorption mechanisms that occur at the soil mineral-water interface. Particular emphasis is placed on literature that discusses Cd adsorption and speciation when associated with iron, manganese, and aluminum oxides and aluminosilicate minerals.Multiple sorption mechanisms by which Cd is sorbed by these minerals have been found, spanning from outer-sphere to inner-sphere to surface precipitation,depending on mineral type, surface loading, and pH. In addition, the application of complementary techniques(e.g.,113 Cd nuclear magnetic resonance(NMR) and molecular dynamics simulation) for probing Cd sorption mechanisms is discussed. This review can help to develop appropriate strategies for the environmental remediation of Cd-contaminated soils.

关键词： aluminosilicate minerals aluminum oxide bioavailability heavy metal iron oxide manganese oxide mineral-water interface molecular-scale sorption mechanisms

MnO/N—C anode materials for lithium-ion batteries prepared by cotton-templated combustion synthesis

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Green Energy & Environment 2017年第4期2卷 377-386页

作者： Cheng-Gong Han Chunyu Zhu Yoshitaka Aoki Hiroki Habazaki Tomohiro Akiyama Faculty of Engineering Hokkaido University

We herein report a facile one-pot synthesis of MnO/N-doped carbon(N—C) composites via a sustainable cotton-template glycineenitrate combustion synthesis to yield superior anode materials for Li ion batteries. MnO nanoparticles with several nanometers were well-embedded in a porous N-doped carbon matrix. It displays the unique characteristics, including the shortened Li^+-ion transport path, increased contact areas with the electrolyte solution, inhibited volume changes and agglomeration of nanoparticles, as well as good conductivity and structural stability during the cycling process, thereby benefiting the superior cycling performance and rate capability. This favorable electrochemical performance of obtained MnO/N—C composites via a one-pot biomass-templated glycine/nitrate combustion synthesis renders the suitability as anode materials for Li-ion batteries.

关键词： Biomass Cotton manganese oxide Lithium ion battery Porous carbon

Oxidative coupling of methane over (Na_2WO_4+Mn or Ce)/SiO_2 catalysts:In situ measurement of electrical conductivity

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Journal of Natural Gas Chemistry 2010年第1期19卷 35-42页

作者： Zeinab Gholipour Azim Malekzadeh Reza Hatami Yadollah Mortazavi Abasali Khodadadi School of Chemistry Damghan University of Basic Sciences (DUBS) P.O. Box 36715/364 Damghan I. R. Iran Catalysis and Nanostructured Materials Research Laboratory School of Chemical Engineering University of Tehran P.O. Box 11365/4563 Tehran I. R. Iran

The effects of manganese oxide or ceria promoters on the performance of Na2WO4/SiO2 catalysts for oxidative coupling of methane （OCM） are reported. The OCM reaction was performed in a continuous-flow microreactor at 800℃, atmospheric pressure and under GHSV = 13200 ml·gCat^-1·h^-1.Catalysts were characterized by in situ conductivity measurement, FT-IR spectroscopy, XRD, SEM and temperature programmed reduction analysis. manganese oxide promoted Na2WO4/SiO2 is considered as one of the active and selective catalysts for OCM reaction. Ceria with high oxygen storage capacity is selected as a proper oxygen activator, providing a higher concentration of the oxy-anion species which is suitable for OCM reaction and compared with manganese oxide. Electrical conductivity of the catalysts was measured in OCM reaction under oxidizing atmosphere, i.e. in the absence of methane. It was found that the trimetallic catalysts, i.e. the catalysts having sodium, tungsten and Mn or Ce species, exhibited similar crystalline structures and morphologies, which lead to suitable bulk properties for the formation of an active and selective catalyst. However, tungsten had significant effect on the texture and redox properties of the catalysts. It was also shown that the crystalline structure of the bimetallic （Na＋Mn or Ce）/SiO2 samples was quite different. This reveals that the metal oxides have significant effect on the extent of crystallization, taking place in the course of interaction of sodium with silica support. Similar conductivities and catalytic performances of （Na2WO4＋Mn or Ce）/SiO2 catalysts propose that the ability of Na2WO4/SiO2 for utilizing oxy-anions formed in presence of different metal oxides is limited.

关键词： oxidative coupling of methane （OCM） conductivity manganese oxide ceria TPR

Formation of Na_(0.44)MnO_(2) Nanowires via Stress-Induced Splitting of Birnessite Nanosheets

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Nano Research 2009年第1期2卷 54-60页

作者： Yanguang Li Yiying Wu Department of Chemistry The Ohio State University100 West 18th AvenueColumbusOhio 43210USA

High aspect ratio Na0.44MnO2 nanowires with a complex one-dimensional(1 D)tunnel structure have been synthesized.We found that the reaction went through layered birnessite nanosheet intermediates,and that their conversion to the final product involved splitting of the nanosheets into nanowires.Based on our observations,a stress-induced splitting mechanism for conversion of birnessite nanosheets to Na0.44MnO2 nanowires is proposed.The final and intermediate phases show topotaxy with〈001〉f//〈020〉b or〈110〉b where frepresents the final Na_(0.44)MnO_(2)phase and b the intermediate birnessite phase.As a result of their high surface areas,the nanowires are efficient catalysts for the oxidation of pinacyanol chloride dye.

关键词： Birnessite manganese oxide nanowire nanosheet stress conversion

Optimized Pt-MnO_(x) interface in Pt-MnO_(x)/3DOM-Al_(2)O_(3)catalysts for enhancing catalytic soot combustion

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Chinese Chemical Letters 2021年第4期32卷 1447-1450页

作者： Jing Xiong Zhenguo Li Peng Zhang Qi Yu Kaixiang Li Yilin Zhang Zhen Zhao Jian Liu Jianmei Li Yuechang Wei National Engineering Laboratory for Mobile Source Emission Control Technology China Automotive Technology&Research Center Co.Ltd.Tianjin 300300China State Key Laboratory of Heavy Oil Processing College of ScienceChina University of PetroleumBeijing 102249China

The catalysts of three-dimensionally ordered macroporous(3 DOM)Al_(2)O_(3)-supported core-shell structured Pt@MnOx nanoparticles(3 DOM-Pt@MnO_(x)/Al_(2)O_(3))were successfully prepared by the gas bubbling-assisted membrane reduction-precipitation(GBMR/P)method.Pt@MnO_(x)core-shell nanoparticles(NPs)are highly dispersed on the inner surface of 3 DOM-Al_(2)O_(3)support.Pt@MnOx/3 DOM-Al_(2)O_(3)catalysts,which combine both advantages of high-efficiency soot-catalyst contact by 3 DOM-Al_(2)O_(3)structure and the abundant active sites by the optimized Pt-MnO_(x)interface,exhibit high catalytic activities for soot combustion,and the catalytic activities are strongly dependent on the thickness of MnO_(x)shell.Among the catalysts,3 DOM-Pt@MnO_(x)/Al_(2)O_(3)-1 catalyst with optimized Pt-MnO_(x)interface shows the highest catalytic activity for soot combustion,i.e.,its values of T_(50)and S_(CO_(2))^(m) are 351℃and98.6%,respectively.The highest density of Pt-MnO_(x)active sites for adsorptio n-activation of gaseous O_(2)is responsible for enhancing catalytic activity for soot combustion.Pt@MnOx/3 DOM-Al_(2)O_(3)catalysts are promising to practical applications for the emission reduction of soot particles.

关键词： 3DOM material Platinum manganese oxide Strong metal-oxide interaction Soot combustion

Rationally designed/constructed MnO_x/WO_3 anode for photoelectrochemical water oxidation

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Chinese Chemical Letters 2018年第6期29卷 811-814页

作者： Xiaohu Cao Xiangyu Zang Xichen Zhou Mindong Chen Yong Ding State Key Laboratory of Applied Organic Chemistry Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province College of Chemistry and Chemical Engineering Lanzhou University Collaborative Innovation Center of Atmospheric Environment and Equipment Technology Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC) Nanjing University of Information Science & Technology

Photoelectrocatalytic water splitting is an effective way to utilize the solar energy to solve the energy shortage. The valence band edge of WO3 located at 3V vs. normal hydrogen electrode（NHE）, which can offer enough potential to kinetically oxidize water for oxygen evolution reaction. However, water oxidation reaction kinetics is sluggish when only WO3 is used as the photoanode. It is highly desirable to use cocatalyst to promote the kinetics. Mn Oxloaded on the WO3 photoanode through photodeposition methods improves the photoelectrochemical water oxidation performance. A maximum photocurrent density of composite photoanode is achieved with a deposition time of 3 min, which is higher than that of pristine WO3 photoanode around 40%. Mn O2 is not only a cocatalyst for water splitting but also for improving oxidation selectivity. We tried to use two means to load Mn Oxon WO3 photoanode material. It is observed that loading a moderate amount of Mn Oxon the WO3 by photodeposition can promote the performance of the WO3 photoanode.

关键词： Photoelectrochemical water oxidation Tungsten oxide manganese oxide Photodeposition Hydrothermal method

Evaluation of charge storage ability of chrome doped Mn2O3 nanostructures derived by cathodic electrodeposition

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Progress in Natural Science:Materials International 2016年第6期26卷 523-527页

作者： Hamideh Darjazi Saied Saeed Hosseiny Davarani Hamid Reza Moazami Taher Yousefi Farideh Tabatabaei Department of Materials Enginnering Naghshe Jahan Institute of Higher Education 2. Faculty of ChemistryShahid Beheshti University 3. School of Physics and acceleratorsNSTRI 4. NFCRSNuclear Science and Technology Research Institute

A facile synthetic route has been proposed to prepare cauliflower-like nanostructures of Cr doped MnO. The synthesis was carried out by constant current cathodic electrodeposition from Mnnitrate solutions containing minor amounts of dichromate. It was found that the presence of Cr mediates the formation of cathodic MnOwhich then reacts with the excess Mnspecies to form MnOnanostructures. X-Ray Diffraction(XRD),Scanning Electron Microscopy(SEM) and Differential Thermal Analysis(DTA) were used to characterize the nanostructures. The storage ability of the obtained nanostructures was investigated by cyclic voltammetry(CV)in 0.5 M NaSOsolution. The results indicated that the Cr doped manganese oxide material shows better performance than the non-doped one, and the charge capacity(SC) of doped manganese oxide(218 F/g) was higher than pure manganese oxide(208 F/g).

关键词： Electro synthesis Nanoparticles Energy storage Supercapacitor manganese oxide