A series of Ce1-xFexO2 （x=0, 0.2, 0.4, 0.6, 0.8, 1） complex oxide catalysts were prepared using the coprecipitation method. The catalysts were characterized by means of XRD and H2-TPR. The reactions between methane ...A series of Ce1-xFexO2 （x=0, 0.2, 0.4, 0.6, 0.8, 1） complex oxide catalysts were prepared using the coprecipitation method. The catalysts were characterized by means of XRD and H2-TPR. The reactions between methane and lattice oxygen from the complex oxides were investigated. The characteristic results revealed that the combination of Ce and Fe oxide in the catalysts could lower the temperature necessary to reduce the cerium oxide. The catalytic activity for selective CH4 oxidation was strongly influenced by dropped Fe species. Adding the appropriate amount of Fe2O3 to CeO2 could promote the action between CH4 and CeO2. Dispersed Fe2O3 first returned to the original state and would then virtually form the Fe species on the catalyst, which could be considered as the active site for selective CH4 oxidation. The appearance of carbon formation was significant and the oxidation of carbon appeared to be the rate-determining step; the amounts of surface reducible oxygen species in CeO2 were also relevant to the activity. Among all the catalysts, Ce0.6Fe0.402 exhibited the best activity, which converted 94.52% of CH4 at 900 ℃.展开更多
A series of CeO2/SiO2 and SixCe1–xO2 complex oxides supported on an activated Al2TiO5-TiO2-SiO2 complex phase (ATS) ceramics were prepared by step impregnation and co-impregnation methods, and characterized by N2-BET...A series of CeO2/SiO2 and SixCe1–xO2 complex oxides supported on an activated Al2TiO5-TiO2-SiO2 complex phase (ATS) ceramics were prepared by step impregnation and co-impregnation methods, and characterized by N2-BET, XRD, SEM and NH3-TPD techniques. The effects of reaction temperature, CeO2/SiO2 loadings and Si/Ce molar ratio on the granular catalysts for NO selective catalytic reduction with ammonia (NH3-SCR) were studied. Results indicated that both CeO2/SiO2/ATS and CeO2/ATS catalysts showed the same ac...展开更多
The cerium iron complex oxides oxygen carrier was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. Th...The cerium iron complex oxides oxygen carrier was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carder could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carders were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carrier： the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species （bulk lattice oxygen） that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction condition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.展开更多
A series of perovskite-type complex oxides LaNi1-xRuxO3 were prepared and studied by means of XRD. The effects of some factors on th complex oxides were discussed. Each kind of those perovskite-type complex oxides was...A series of perovskite-type complex oxides LaNi1-xRuxO3 were prepared and studied by means of XRD. The effects of some factors on th complex oxides were discussed. Each kind of those perovskite-type complex oxides was used to prepare cathode by composite-electroplating technique. The cathodes were electrochemically charactrized. The results show that these novel cathode exhibit high activities and excellent stabilities during long-term continuous electrolysis with some current interruptions.展开更多
The 1,3,5-triazine diphosphine oxide ligands with donor-acceptor properties formed strong complexes with europium（Ⅲ） ion in acetonitrile. Spectrophotometric titrations and mass spectra indicated that two ligands co...The 1,3,5-triazine diphosphine oxide ligands with donor-acceptor properties formed strong complexes with europium（Ⅲ） ion in acetonitrile. Spectrophotometric titrations and mass spectra indicated that two ligands coordinated to one europium ion. The stability constants varied from 11.64 to 14.60 （log 13）. Binary complexes exhibited rather weak luminescence in solution. 1,3,5-triazine diphosphine oxides engaged as co-ligands in Eu（Ⅲ） （2-thenoyltrifluoroacetonate）3 complex contributed to the overall photoluminescence and allowed for excitation with longer wavelengths than the parent complex.展开更多
In this manuscript, we have demonstrated the delicate design and synthesis of bimetallic oxides nanoparticles derived from metal–oleate complex embedded in 3D graphene networks(MnO/CoMn_2O_4 GN), as an anode mater...In this manuscript, we have demonstrated the delicate design and synthesis of bimetallic oxides nanoparticles derived from metal–oleate complex embedded in 3D graphene networks(MnO/CoMn_2O_4 GN), as an anode material for lithium ion batteries. The novel synthesis of the MnO/CoMn_2O_4 GN consists of thermal decomposition of metal–oleate complex containing cobalt and manganese metals and oleate ligand, forming bimetallic oxides nanoparticles, followed by a selfassembly route with reduced graphene oxides. The MnO/CoMn_2O_4 GN composite, with a unique architecture of bimetallic oxides nanoparticles encapsulated in 3D graphene networks, rationally integrates several benefits including shortening the di usion path of Li^+ ions, improving electrical conductivity and mitigating volume variation during cycling. Studies show that the electrochemical reaction processes of MnO/Co Mn_2O_4 GN electrodes are dominated by the pseudocapacitive behavior, leading to fast Li^+ charge/discharge reactions. As a result, the MnO/CoMn_2O_4 GN manifests high initial specific capacity, stable cycling performance, and excellent rate capability.展开更多
The methylene-selective oxidation of simple alkanes catalyzed by a nonheme iron(Ⅲ)-monoamidate complex using H_(2)O_(2)as the terminal oxidant is reported.Mechanistic studies suggest that iron(V)-oxo species is the a...The methylene-selective oxidation of simple alkanes catalyzed by a nonheme iron(Ⅲ)-monoamidate complex using H_(2)O_(2)as the terminal oxidant is reported.Mechanistic studies suggest that iron(V)-oxo species is the active intermediate,undergoing hydrogen atom abstraction(HAA)as the rate-determining step to initiate C-H bond activation.展开更多
Hydrotalcites known as anionic clays are found in nature. Hydrotalcites, hydrotalcite-like compounds, and calcined hydrotalcites (as mixed or complex oxides) as highly active, selective catalysts play an important rol...Hydrotalcites known as anionic clays are found in nature. Hydrotalcites, hydrotalcite-like compounds, and calcined hydrotalcites (as mixed or complex oxides) as highly active, selective catalysts play an important role in many base/catalyzed reactions. Mg/Al hydrotalcite (MAH) as precursor was used to prepare Mg/Al metal complex oxides (MAO), used as epoxidation catalysts in the current research. In this paper, some primary physical and catalytic properties of MAH and MAO were investigated. The results indicated that the qualified MAH (Mg/Al mol ratio of 3) can be achieved when the suspension was crystallized under 80°C for 16h, and after being filtered, dried at 100 °C for 5h in a oven. MAO was prepared by calcining MAH for 4h in a muffle furnace, and calcination temperature was determined to be 500 °C by a differential scanning calorimeter (DSC). Crystal structure and parameters of MAH and MAO were characterized by X/ray diffraction (XRD), good crystal structure was observed and typical peaks of MAH were detected when 2θ was at 11.5 (003), 23.0 (006), 35.0 (009), and 61.0 (110), respectively. The morphology of calcined precursor, i.e. MAO, was investigated with scanning electron microscopy (SEM);the finer lamellar structure and smaller average size of 3μm was observed. Molding research was performed and confirmed by SEM, the results indicated that the surface bulge and cavity with size of several micrometers were increased, which simultaneously suggested the increasing of specific surface area. The catalytic activity of molding MAO was finally examined by using octanol as starting reagent and ethylene oxide as reactant, and narrower molecular distribution was observed comparing with the traditional catalyst-KOH.展开更多
Perovskite oxides(ABO_(3))are thought to be promising electrocatalysts for oxygen evolution reaction(OER),but their specific surface area(SSA)is too low(usually<10 m^(2) g^(−1)).Developing advanced ABO_(3) electroc...Perovskite oxides(ABO_(3))are thought to be promising electrocatalysts for oxygen evolution reaction(OER),but their specific surface area(SSA)is too low(usually<10 m^(2) g^(−1)).Developing advanced ABO_(3) electrocatalysts with high SSA and optimized structure is of great significance but remains a tremendous challenge.Herein,we propose a general strategy for fabrication of mesoporous perovskite oxide nanosheets(MPONs)with controllable atomic doping via self-sacrificial template-induced nanostructure modulation.A variety of MPONs including LaFeO_(3),A-site-doped LaFeO_(3)(A-LaFeO_(3),where A is Pr,Nd,Sm,Eu,or Gd)and B-site-doped LaFeO_(3)(B-LaFeO_(3),where B is Mn,Co,Ni,Cu,or Zn)have been achieved.Interestingly,it is discovered that the catalytic activities of A-LaFeO_(3) MPONs as OER catalysts are overall higher than those of B-LaFeO_(3) ones.Especially,the screened Eu-LaFeO_(3) MPONs only require a low overpotential of 267 mV at 10 mA cm^(−2),outperforming most reported perovskite oxides.The superior catalytic activity of Eu-LaFeO_(3) MPONs is attributed to their favorable porous structure,which increases the density of active sites,and enhanced lattice oxygen participation,which improves the intrinsic activity.This study provides guidance for the design and controlled synthesis of advanced rare-earth-doped MPONs with ultrahigh SSA for enhanced electrocatalysis.展开更多
The pyrochlore supergroup natural minerals are the oxides for formula A2-xB2O7. In this formula, A typically is Ca, Na, TR, Ba, Fe and Mn cation. B is Ta, Ti, Nb, W, Sb. The pyrochlore supergroup is divided into five ...The pyrochlore supergroup natural minerals are the oxides for formula A2-xB2O7. In this formula, A typically is Ca, Na, TR, Ba, Fe and Mn cation. B is Ta, Ti, Nb, W, Sb. The pyrochlore supergroup is divided into five groups basis of the atomic proportions of the B-site atoms Nb, Ta, Sb, Ti, and W. They are pyrochlore, microlite, roméite, betafite, and elsmoreite, respectively. Some of these minerals containing rare-earth elements species or synthetic oxides have important applications in materials, as for optical materials, light catalyst materials, magnetoelectric materials and radioactive waste treatment etc.展开更多
The phosphorus（P） fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid（HA） complexes were analyzed using the ultrafiltration method in this...The phosphorus（P） fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid（HA） complexes were analyzed using the ultrafiltration method in this study.With an initial P concentration of 20 mg/L（I =0.01 mol/L and pH = 7）,it was shown that the colloid（1 kDa-0.45 μm） component of P accounted for 10.6%,11.6%,6.5%,and 4.0%of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite（FH）,goethite（GE）,ferrihydrite-humic acid complex（FH-HA）,goethite-humic acid complex（GE-HA）,respectively.The 〈1 kDa component of P was still the predominant fraction in the supernatant,and underestimated colloidal P accounted for 2.2%,55.1%,45.5%,and 38.7%of P adsorption onto the solid surface of FH,FH-HA,GE and GE-HA,respectively.Thus,the colloid P could not be neglected.Notably,it could be interpreted that Fe3＋ hydrolysis from the adsorbents followed by the formation of colloidal hydrous ferric oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant.And colloidal adsorbent particles co-existing in the supernatant were another important reason for it.Additionally,dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant.Ultimately,we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P,even when considering other contaminants such as organic pollutants,heavy metal ions,and arsenate at the sediment/soil-water interface in the real environment.展开更多
In the present paper,a silicon nitride-based composite processed with rare-earth oxidesadditives is presented.Its bend strength can be maintained at a value as high as 1000 MPafrom 1000 to 1370℃ and the fracture toug...In the present paper,a silicon nitride-based composite processed with rare-earth oxidesadditives is presented.Its bend strength can be maintained at a value as high as 1000 MPafrom 1000 to 1370℃ and the fracture toughness measures 9-10 MPa·m<sup>1/2</sup>.The static fa-tigue behavior at 1370℃ of this material is also encouraging.Besides,two another α′/β′sialon composites doped with rare-earth oxides are also described.The effects of processingparameters on the microstructure and the properties of the materials are discussed in somedetails.展开更多
In view of the growing interest in molecular orbitals (MOs) encountered in certain complex oxides, we review some of their properties from the band theory perspective and provide detailed examples based on real materi...In view of the growing interest in molecular orbitals (MOs) encountered in certain complex oxides, we review some of their properties from the band theory perspective and provide detailed examples based on real materials. Our discussion includes some technical aspects of identifying MOs in electronic structure calculations and considers cases when MOs can be both orthogonal and non-orthogonal. We also describe orthonormalization of MOs, a procedure converting them into Wannier functions, and discuss the problem of Wannier functions possibly being rather spatially extended and how using MO, rather than atomic orbital, based effective Hamiltonians might be a better choice in describing certain strongly correlated systems as well as systems with strong electron-phonon coupling. Furthermore, we address the problem of strongly correlated MOs and how it can be treated in band theory calculations.展开更多
This is a mini-review-like article including our recent results and methods for （new） metal oxides and （previously reported） composite materials composed of metal complexes and metal oxides for comparison to enhan...This is a mini-review-like article including our recent results and methods for （new） metal oxides and （previously reported） composite materials composed of metal complexes and metal oxides for comparison to enhance anisotropic structural changes intentionally. Some complex inorganic oxides are known that they may be promising color materials （absorbing visible light of certain wavelengths region） having potential application for environmentally benign catalysts, for example, photocatalysts. Chiral copper（Ⅱ） complexes having bidentate amine ligands （[CuL2]2＋） can be acted as cationic building blocks of bimetallic metal complexes. We have prepared some chiral bimetallic complexes with various anionic metal complexes such as [PtCl4]2-, [M02O7]2 and Mn12 clusters （typical single-molecule magnets） which characterized by means of solid-state electronic and CD （circular dichroism） spectra, IR （infrared） spectra, synchrotron XRD （X-ray diffraction） and XAS （soft X-ray absorption spectroscopy）. By sintering these precursor chiral bimetallic complexes, we have prepared complex inorganic oxides from them. The IR spectra indicated substituting metal-ligand bonds and losing organic moieties. The XRD pattern indicated complete changes of crystal structures. The XAS revealed replacing coordination atoms as well as oxidation of valences of metal ions. Furthermore, we will also investigate possibility of patterning by homogeneous precipitation method as bimetallic complexes to prepare desirable complex inorganic oxides.展开更多
In this paper,the influence of crystal-field on the Luminescence properties of Eu^(2+) in complex oxides are studied theoretically by using purely electrostatic model,the dependence of the 4f^65d levels on Eu-O bond d...In this paper,the influence of crystal-field on the Luminescence properties of Eu^(2+) in complex oxides are studied theoretically by using purely electrostatic model,the dependence of the 4f^65d levels on Eu-O bond distance is given.Quantum chemistry calculation shows that the splitting extent of 4f^65d energy band in cubic or in octahedral fields will be inversely proportional to R^5,where R is the distance of Eu^(2+) to oxygen ligand.The value of R affects slightly the location of the centre of 4f^65d energy band.According to the exper- imental spectrum data,we have discussed the influence of the host chemical composition,the replaced sites of Eu^(2+) and degree of covalency of Eu-O bond on luminescence properties of Eu^(2+).Some regularity of fluorescence spectrum was observed. In alkali-alkaline earth-phosphates,the splitting extent of 4f^65d band (△E) becomes smaller as the Eu-O bond distance (R) increases.In Na_(3-x)(PO_4)_(1-x)(SO_4)_x and Na_(2-x)CaSi_(1-x)P_xO_4 hosts,d-d emission peak of Eu^(2+) will shift to shorter wavelength with the increase of x's value. The crystal structure data show that Eu^(2+) in K_2Mg_2(SO_4)_3 is affected more strongly by crystal-field and covalancy than in KMgF_3,so K_2Mg_2(SO_4)_3:Eu^(2+) emits blue light (E_(em)~m=400nm) and KMgF_3:Eu^(2+) produces ultraviolet fluorescence.展开更多
New solid complexes of europium, uranyl and zinc ions with N-oxides of 4-chloro-2,6-dimethylpyridine, quinoline and 4-meth- oxyquinaldinic acid in presence different anions were obtained and characterized by elemental...New solid complexes of europium, uranyl and zinc ions with N-oxides of 4-chloro-2,6-dimethylpyridine, quinoline and 4-meth- oxyquinaldinic acid in presence different anions were obtained and characterized by elemental and TG analyses, IR and luminescence spectra. The compounds are crystalline, hydrated or anhydrous salts with colours typical of metal ions. Thermal studies showed that in hydrated salts lattice or coordination water molecules are present. A role of different anions in the formation of various types of the complexes is presented.展开更多
As novel negative electrode materials for alkaline batteries, the electrochemical properties of four lanthanum transition-metal (La-TM) complex oxides LaTiO(3), LaVO(4), LaCrO(3) and LaMnO(3) were investigated. X-ray ...As novel negative electrode materials for alkaline batteries, the electrochemical properties of four lanthanum transition-metal (La-TM) complex oxides LaTiO(3), LaVO(4), LaCrO(3) and LaMnO(3) were investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) were employed to characterize their microstructures. All the La-TM oxides were made up of single phases. Electrochemical measurements showed that the maximum discharge capacities of LaTiO(3), LaVO(4), LaCrO(3), and LaMnO(3) electrodes at 303 K were 367, 187, 318, and 278 mAh/g, respectively. X-ray photoelectron spectroscopy (XPS) and XRD Rietveld analysis were carried out to discuss the electrochemical reaction mechanism. Electrode kinetics was studied by electrochemical impedance spectrum (EIS). The results showed that the maximum discharge capacity was directly related to the charge-transfer resistance (R(ct)) of La-TM oxide electrode. The cyclic properties of the four oxides should be further improved and the discharge capacity of LaMnO(3) (about 96 mAh/g) was the highest after 10(th) charge/discharge cycles.展开更多
The catalytic epoxidation of olefin was investigated on two copper complex-modified molybdenum oxides with a 3D supramolecular structure, [Cu（bipy）]4[Mo15O47].2H2O （1） and [Cu1（bix）][（Cu1bix） （δ-MoVl8O26）0....The catalytic epoxidation of olefin was investigated on two copper complex-modified molybdenum oxides with a 3D supramolecular structure, [Cu（bipy）]4[Mo15O47].2H2O （1） and [Cu1（bix）][（Cu1bix） （δ-MoVl8O26）0.5] （2） （bipy = 4,4＇-bipyridine, bix = 1,4-bis（imidazole-1-ylmethyl）benzene）. Both compounds were catalytically active and stable for the epoxidation of cyclooctene, 1-octene, and styrene with tert-butyl hydroperoxide （t-BuOOH） as oxidant. The excellent catalytic performance was attributed to the presence of stable coordination bonds between the molybdenum oxide and copper complex, which resulted in the formation of easily accessible Mo species with high electropositivity. In addition, the copper complex also acted as an active site for the activation of t-BuOOH, thus im- proving these copper complex-modified polyoxometalates.展开更多
Rice-duck （RD） and rice-fish （RF） ecological systems are major complex planting and breeding models of rice paddy fields in southern China. Studying the methane （CH4） and nitrous oxide （N2O） emissions and thei...Rice-duck （RD） and rice-fish （RF） ecological systems are major complex planting and breeding models of rice paddy fields in southern China. Studying the methane （CH4） and nitrous oxide （N2O） emissions and their economic value from these two ecosystems can provide theoretical and practical basis for further development and utilization of these classical agricultural techniques. CH4 and N2O emissions from RD and RF ecological systems were measured in situ by using static chambers technique. Using global warming potentials （GWPs）, we assessed the greenhouse effect of CH4 and N2O and their economic value. Results showed that the peaks of CH4 emission fluxes from RD and RF appeared at full tillering stage and at heading stage, and the average emission fluxes were significantly （P〈 0.05） lower than that from CK. N2O fluxes remained low when the field is flooded and high after draining the water. Compared with CK, the total amount of N2O emissions was significantly （P〈0.05） higher and slightly lower than those from RD and RF, respectively. In 2006 and 2007, the total greenhouse effect of CH4 and N20 from RD and RF were 4 728.3 and 4 611 kg CO2 ha^-1, 4 545 and 4 754.3 kg CO2 ha^-1, respectively. The costs of greenhouse effect were 970.89 and 946.81 RMB yuan ha^-1, and 933.25 and 976.23 RMB yuan ha^-1, respectively, which were significant lower than those from CK （5 997.6 and 5 391.5 RMB yuan ha^-1）. Except for the environment cost of CH4 and N2O, the economic benefits from RD and RF were 2 210.64 and 4 881.92 RMB yuan ha^-1; 3 798.37 and 5 310.64 RMB yuan ha^-1, respectively, higher than those from CK. Therefore, RD and RF complex ecological planting and breeding models can effectively decrease and control CH4 and N2O emissions, and they are two of the effective strategies to reduce greenhouse gases from rice paddy fields and contribute in alleviating global warming. Thus, their adoption is important to the environment together with their economy benefits.展开更多
Two cobalt（Ⅱ） complexes 1 and 2 of Schiff bases derived from amino acids were synthesized and used for oxidation of benzyl alcohol with molecular oxygen at different conditions of pH,solvent,temperature and complex...Two cobalt（Ⅱ） complexes 1 and 2 of Schiff bases derived from amino acids were synthesized and used for oxidation of benzyl alcohol with molecular oxygen at different conditions of pH,solvent,temperature and complex/alcohol molar ratio to optimize reaction conditions and to evaluate the catalytic efficiency of new cobalt Schiff base complexes.Under obtained optimum conditions,various alcohols were oxidized to corresponding aldehydes and ketones.展开更多
基金the National Natural Science Foundation of China (50574046)National Natural Science Foundation of Major Research Projects (90610035)+1 种基金Natural Science Foundation of Yunnan Province (2004E0058Q)High School Doctoral Subject Special Science and Re- search Foundation of Ministry of Education (20040674005)
文摘A series of Ce1-xFexO2 （x=0, 0.2, 0.4, 0.6, 0.8, 1） complex oxide catalysts were prepared using the coprecipitation method. The catalysts were characterized by means of XRD and H2-TPR. The reactions between methane and lattice oxygen from the complex oxides were investigated. The characteristic results revealed that the combination of Ce and Fe oxide in the catalysts could lower the temperature necessary to reduce the cerium oxide. The catalytic activity for selective CH4 oxidation was strongly influenced by dropped Fe species. Adding the appropriate amount of Fe2O3 to CeO2 could promote the action between CH4 and CeO2. Dispersed Fe2O3 first returned to the original state and would then virtually form the Fe species on the catalyst, which could be considered as the active site for selective CH4 oxidation. The appearance of carbon formation was significant and the oxidation of carbon appeared to be the rate-determining step; the amounts of surface reducible oxygen species in CeO2 were also relevant to the activity. Among all the catalysts, Ce0.6Fe0.402 exhibited the best activity, which converted 94.52% of CH4 at 900 ℃.
基金Project supported by the National High-Tech Research and Development Program of China (2009AA05Z313)National Natural Science Foundation of China (50872052)Foundation of Jiangsu Province of China for College Postgraduate Students in Innovation Engineering (CX07B_083z)
文摘A series of CeO2/SiO2 and SixCe1–xO2 complex oxides supported on an activated Al2TiO5-TiO2-SiO2 complex phase (ATS) ceramics were prepared by step impregnation and co-impregnation methods, and characterized by N2-BET, XRD, SEM and NH3-TPD techniques. The effects of reaction temperature, CeO2/SiO2 loadings and Si/Ce molar ratio on the granular catalysts for NO selective catalytic reduction with ammonia (NH3-SCR) were studied. Results indicated that both CeO2/SiO2/ATS and CeO2/ATS catalysts showed the same ac...
基金the National Natural Science Foundation of China (50574046)National Natural Science Foundation of Major Research Projects (90610035)+1 种基金Natural Science Foundation of Yunnan Province (2004E0058Q)High School Doctoral Subject Special Science and Research Foundation of Ministry of Education (20040674005)
文摘The cerium iron complex oxides oxygen carrier was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carder could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carders were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carrier： the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species （bulk lattice oxygen） that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction condition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.
文摘A series of perovskite-type complex oxides LaNi1-xRuxO3 were prepared and studied by means of XRD. The effects of some factors on th complex oxides were discussed. Each kind of those perovskite-type complex oxides was used to prepare cathode by composite-electroplating technique. The cathodes were electrochemically charactrized. The results show that these novel cathode exhibit high activities and excellent stabilities during long-term continuous electrolysis with some current interruptions.
基金support from the Polish Ministry of Science and Higher Education (3T09A 081 28)
文摘The 1,3,5-triazine diphosphine oxide ligands with donor-acceptor properties formed strong complexes with europium（Ⅲ） ion in acetonitrile. Spectrophotometric titrations and mass spectra indicated that two ligands coordinated to one europium ion. The stability constants varied from 11.64 to 14.60 （log 13）. Binary complexes exhibited rather weak luminescence in solution. 1,3,5-triazine diphosphine oxides engaged as co-ligands in Eu（Ⅲ） （2-thenoyltrifluoroacetonate）3 complex contributed to the overall photoluminescence and allowed for excitation with longer wavelengths than the parent complex.
基金financial support from National Natural Science Foundation of China (No. 21373006 and No. 51801030)the Science and Technology Program of Suzhou (SYG201732)+4 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the project of Scientific and Technologic Infrastructure of Suzhou (SZS201708)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (17KJB430029)One-hundred Young Talents (Class A) of Guangdong University of Technology (No. 220413198)Natural Science Foundation of Guangdong Providence (No. 2018A030310571)
文摘In this manuscript, we have demonstrated the delicate design and synthesis of bimetallic oxides nanoparticles derived from metal–oleate complex embedded in 3D graphene networks(MnO/CoMn_2O_4 GN), as an anode material for lithium ion batteries. The novel synthesis of the MnO/CoMn_2O_4 GN consists of thermal decomposition of metal–oleate complex containing cobalt and manganese metals and oleate ligand, forming bimetallic oxides nanoparticles, followed by a selfassembly route with reduced graphene oxides. The MnO/CoMn_2O_4 GN composite, with a unique architecture of bimetallic oxides nanoparticles encapsulated in 3D graphene networks, rationally integrates several benefits including shortening the di usion path of Li^+ ions, improving electrical conductivity and mitigating volume variation during cycling. Studies show that the electrochemical reaction processes of MnO/Co Mn_2O_4 GN electrodes are dominated by the pseudocapacitive behavior, leading to fast Li^+ charge/discharge reactions. As a result, the MnO/CoMn_2O_4 GN manifests high initial specific capacity, stable cycling performance, and excellent rate capability.
文摘The methylene-selective oxidation of simple alkanes catalyzed by a nonheme iron(Ⅲ)-monoamidate complex using H_(2)O_(2)as the terminal oxidant is reported.Mechanistic studies suggest that iron(V)-oxo species is the active intermediate,undergoing hydrogen atom abstraction(HAA)as the rate-determining step to initiate C-H bond activation.
文摘Hydrotalcites known as anionic clays are found in nature. Hydrotalcites, hydrotalcite-like compounds, and calcined hydrotalcites (as mixed or complex oxides) as highly active, selective catalysts play an important role in many base/catalyzed reactions. Mg/Al hydrotalcite (MAH) as precursor was used to prepare Mg/Al metal complex oxides (MAO), used as epoxidation catalysts in the current research. In this paper, some primary physical and catalytic properties of MAH and MAO were investigated. The results indicated that the qualified MAH (Mg/Al mol ratio of 3) can be achieved when the suspension was crystallized under 80°C for 16h, and after being filtered, dried at 100 °C for 5h in a oven. MAO was prepared by calcining MAH for 4h in a muffle furnace, and calcination temperature was determined to be 500 °C by a differential scanning calorimeter (DSC). Crystal structure and parameters of MAH and MAO were characterized by X/ray diffraction (XRD), good crystal structure was observed and typical peaks of MAH were detected when 2θ was at 11.5 (003), 23.0 (006), 35.0 (009), and 61.0 (110), respectively. The morphology of calcined precursor, i.e. MAO, was investigated with scanning electron microscopy (SEM);the finer lamellar structure and smaller average size of 3μm was observed. Molding research was performed and confirmed by SEM, the results indicated that the surface bulge and cavity with size of several micrometers were increased, which simultaneously suggested the increasing of specific surface area. The catalytic activity of molding MAO was finally examined by using octanol as starting reagent and ethylene oxide as reactant, and narrower molecular distribution was observed comparing with the traditional catalyst-KOH.
基金financially supported by the National Key Research and Development Program(Nos.2022YFB2502104 and 2022YFA1602700)the Key Research and Development Program of Jiangsu Provincial Department of Science and Technology of China(No.BE2022332)+4 种基金the Jiangsu Carbon Peak Carbon Neutralization Science and Technology Innovation Special Fund(No.BE2022605)the National Natural Science Foundation of China(Nos.22109073,22379071)the DECRA program of Australian Research Council(No.DE230100357)the JSPS KAKENHI(No.JP23K13703)the Center for Computational Materials Science,Institute for Materials Research,Tohoku University for the use of MASAMUNE-IMR(202312-SCKXX-0203)。
文摘Perovskite oxides(ABO_(3))are thought to be promising electrocatalysts for oxygen evolution reaction(OER),but their specific surface area(SSA)is too low(usually<10 m^(2) g^(−1)).Developing advanced ABO_(3) electrocatalysts with high SSA and optimized structure is of great significance but remains a tremendous challenge.Herein,we propose a general strategy for fabrication of mesoporous perovskite oxide nanosheets(MPONs)with controllable atomic doping via self-sacrificial template-induced nanostructure modulation.A variety of MPONs including LaFeO_(3),A-site-doped LaFeO_(3)(A-LaFeO_(3),where A is Pr,Nd,Sm,Eu,or Gd)and B-site-doped LaFeO_(3)(B-LaFeO_(3),where B is Mn,Co,Ni,Cu,or Zn)have been achieved.Interestingly,it is discovered that the catalytic activities of A-LaFeO_(3) MPONs as OER catalysts are overall higher than those of B-LaFeO_(3) ones.Especially,the screened Eu-LaFeO_(3) MPONs only require a low overpotential of 267 mV at 10 mA cm^(−2),outperforming most reported perovskite oxides.The superior catalytic activity of Eu-LaFeO_(3) MPONs is attributed to their favorable porous structure,which increases the density of active sites,and enhanced lattice oxygen participation,which improves the intrinsic activity.This study provides guidance for the design and controlled synthesis of advanced rare-earth-doped MPONs with ultrahigh SSA for enhanced electrocatalysis.
基金Supported by National Natural Science Foundation of China (Grant No. 41172052)
文摘The pyrochlore supergroup natural minerals are the oxides for formula A2-xB2O7. In this formula, A typically is Ca, Na, TR, Ba, Fe and Mn cation. B is Ta, Ti, Nb, W, Sb. The pyrochlore supergroup is divided into five groups basis of the atomic proportions of the B-site atoms Nb, Ta, Sb, Ti, and W. They are pyrochlore, microlite, roméite, betafite, and elsmoreite, respectively. Some of these minerals containing rare-earth elements species or synthetic oxides have important applications in materials, as for optical materials, light catalyst materials, magnetoelectric materials and radioactive waste treatment etc.
基金supported by the National Natural Science Foundation of China(nos.41171198,41403079)the Chongqing Research Program of Basic Research and Frontier Technology(no.cstc2015jcyj A20021)the Fundamental Research Funds for the Central Universities of Ministry of Education of China(no.XDJK2015B035)
文摘The phosphorus（P） fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid（HA） complexes were analyzed using the ultrafiltration method in this study.With an initial P concentration of 20 mg/L（I =0.01 mol/L and pH = 7）,it was shown that the colloid（1 kDa-0.45 μm） component of P accounted for 10.6%,11.6%,6.5%,and 4.0%of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite（FH）,goethite（GE）,ferrihydrite-humic acid complex（FH-HA）,goethite-humic acid complex（GE-HA）,respectively.The 〈1 kDa component of P was still the predominant fraction in the supernatant,and underestimated colloidal P accounted for 2.2%,55.1%,45.5%,and 38.7%of P adsorption onto the solid surface of FH,FH-HA,GE and GE-HA,respectively.Thus,the colloid P could not be neglected.Notably,it could be interpreted that Fe3＋ hydrolysis from the adsorbents followed by the formation of colloidal hydrous ferric oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant.And colloidal adsorbent particles co-existing in the supernatant were another important reason for it.Additionally,dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant.Ultimately,we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P,even when considering other contaminants such as organic pollutants,heavy metal ions,and arsenate at the sediment/soil-water interface in the real environment.
基金the High Technology Research and Development Programme of China.
文摘In the present paper,a silicon nitride-based composite processed with rare-earth oxidesadditives is presented.Its bend strength can be maintained at a value as high as 1000 MPafrom 1000 to 1370℃ and the fracture toughness measures 9-10 MPa·m<sup>1/2</sup>.The static fa-tigue behavior at 1370℃ of this material is also encouraging.Besides,two another α′/β′sialon composites doped with rare-earth oxides are also described.The effects of processingparameters on the microstructure and the properties of the materials are discussed in somedetails.
文摘In view of the growing interest in molecular orbitals (MOs) encountered in certain complex oxides, we review some of their properties from the band theory perspective and provide detailed examples based on real materials. Our discussion includes some technical aspects of identifying MOs in electronic structure calculations and considers cases when MOs can be both orthogonal and non-orthogonal. We also describe orthonormalization of MOs, a procedure converting them into Wannier functions, and discuss the problem of Wannier functions possibly being rather spatially extended and how using MO, rather than atomic orbital, based effective Hamiltonians might be a better choice in describing certain strongly correlated systems as well as systems with strong electron-phonon coupling. Furthermore, we address the problem of strongly correlated MOs and how it can be treated in band theory calculations.
文摘This is a mini-review-like article including our recent results and methods for （new） metal oxides and （previously reported） composite materials composed of metal complexes and metal oxides for comparison to enhance anisotropic structural changes intentionally. Some complex inorganic oxides are known that they may be promising color materials （absorbing visible light of certain wavelengths region） having potential application for environmentally benign catalysts, for example, photocatalysts. Chiral copper（Ⅱ） complexes having bidentate amine ligands （[CuL2]2＋） can be acted as cationic building blocks of bimetallic metal complexes. We have prepared some chiral bimetallic complexes with various anionic metal complexes such as [PtCl4]2-, [M02O7]2 and Mn12 clusters （typical single-molecule magnets） which characterized by means of solid-state electronic and CD （circular dichroism） spectra, IR （infrared） spectra, synchrotron XRD （X-ray diffraction） and XAS （soft X-ray absorption spectroscopy）. By sintering these precursor chiral bimetallic complexes, we have prepared complex inorganic oxides from them. The IR spectra indicated substituting metal-ligand bonds and losing organic moieties. The XRD pattern indicated complete changes of crystal structures. The XAS revealed replacing coordination atoms as well as oxidation of valences of metal ions. Furthermore, we will also investigate possibility of patterning by homogeneous precipitation method as bimetallic complexes to prepare desirable complex inorganic oxides.
文摘In this paper,the influence of crystal-field on the Luminescence properties of Eu^(2+) in complex oxides are studied theoretically by using purely electrostatic model,the dependence of the 4f^65d levels on Eu-O bond distance is given.Quantum chemistry calculation shows that the splitting extent of 4f^65d energy band in cubic or in octahedral fields will be inversely proportional to R^5,where R is the distance of Eu^(2+) to oxygen ligand.The value of R affects slightly the location of the centre of 4f^65d energy band.According to the exper- imental spectrum data,we have discussed the influence of the host chemical composition,the replaced sites of Eu^(2+) and degree of covalency of Eu-O bond on luminescence properties of Eu^(2+).Some regularity of fluorescence spectrum was observed. In alkali-alkaline earth-phosphates,the splitting extent of 4f^65d band (△E) becomes smaller as the Eu-O bond distance (R) increases.In Na_(3-x)(PO_4)_(1-x)(SO_4)_x and Na_(2-x)CaSi_(1-x)P_xO_4 hosts,d-d emission peak of Eu^(2+) will shift to shorter wavelength with the increase of x's value. The crystal structure data show that Eu^(2+) in K_2Mg_2(SO_4)_3 is affected more strongly by crystal-field and covalancy than in KMgF_3,so K_2Mg_2(SO_4)_3:Eu^(2+) emits blue light (E_(em)~m=400nm) and KMgF_3:Eu^(2+) produces ultraviolet fluorescence.
文摘New solid complexes of europium, uranyl and zinc ions with N-oxides of 4-chloro-2,6-dimethylpyridine, quinoline and 4-meth- oxyquinaldinic acid in presence different anions were obtained and characterized by elemental and TG analyses, IR and luminescence spectra. The compounds are crystalline, hydrated or anhydrous salts with colours typical of metal ions. Thermal studies showed that in hydrated salts lattice or coordination water molecules are present. A role of different anions in the formation of various types of the complexes is presented.
基金Project supported by the National Natural Science Foundation of China (50971096)
文摘As novel negative electrode materials for alkaline batteries, the electrochemical properties of four lanthanum transition-metal (La-TM) complex oxides LaTiO(3), LaVO(4), LaCrO(3) and LaMnO(3) were investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) were employed to characterize their microstructures. All the La-TM oxides were made up of single phases. Electrochemical measurements showed that the maximum discharge capacities of LaTiO(3), LaVO(4), LaCrO(3), and LaMnO(3) electrodes at 303 K were 367, 187, 318, and 278 mAh/g, respectively. X-ray photoelectron spectroscopy (XPS) and XRD Rietveld analysis were carried out to discuss the electrochemical reaction mechanism. Electrode kinetics was studied by electrochemical impedance spectrum (EIS). The results showed that the maximum discharge capacity was directly related to the charge-transfer resistance (R(ct)) of La-TM oxide electrode. The cyclic properties of the four oxides should be further improved and the discharge capacity of LaMnO(3) (about 96 mAh/g) was the highest after 10(th) charge/discharge cycles.
基金supported by the National Natural Science Foundation of China(21173100 and 21320102001)~~
文摘The catalytic epoxidation of olefin was investigated on two copper complex-modified molybdenum oxides with a 3D supramolecular structure, [Cu（bipy）]4[Mo15O47].2H2O （1） and [Cu1（bix）][（Cu1bix） （δ-MoVl8O26）0.5] （2） （bipy = 4,4＇-bipyridine, bix = 1,4-bis（imidazole-1-ylmethyl）benzene）. Both compounds were catalytically active and stable for the epoxidation of cyclooctene, 1-octene, and styrene with tert-butyl hydroperoxide （t-BuOOH） as oxidant. The excellent catalytic performance was attributed to the presence of stable coordination bonds between the molybdenum oxide and copper complex, which resulted in the formation of easily accessible Mo species with high electropositivity. In addition, the copper complex also acted as an active site for the activation of t-BuOOH, thus im- proving these copper complex-modified polyoxometalates.
基金supported by Important National Science&Technoligy Specific Projects, China (2004BA520A02)
文摘Rice-duck （RD） and rice-fish （RF） ecological systems are major complex planting and breeding models of rice paddy fields in southern China. Studying the methane （CH4） and nitrous oxide （N2O） emissions and their economic value from these two ecosystems can provide theoretical and practical basis for further development and utilization of these classical agricultural techniques. CH4 and N2O emissions from RD and RF ecological systems were measured in situ by using static chambers technique. Using global warming potentials （GWPs）, we assessed the greenhouse effect of CH4 and N2O and their economic value. Results showed that the peaks of CH4 emission fluxes from RD and RF appeared at full tillering stage and at heading stage, and the average emission fluxes were significantly （P〈 0.05） lower than that from CK. N2O fluxes remained low when the field is flooded and high after draining the water. Compared with CK, the total amount of N2O emissions was significantly （P〈0.05） higher and slightly lower than those from RD and RF, respectively. In 2006 and 2007, the total greenhouse effect of CH4 and N20 from RD and RF were 4 728.3 and 4 611 kg CO2 ha^-1, 4 545 and 4 754.3 kg CO2 ha^-1, respectively. The costs of greenhouse effect were 970.89 and 946.81 RMB yuan ha^-1, and 933.25 and 976.23 RMB yuan ha^-1, respectively, which were significant lower than those from CK （5 997.6 and 5 391.5 RMB yuan ha^-1）. Except for the environment cost of CH4 and N2O, the economic benefits from RD and RF were 2 210.64 and 4 881.92 RMB yuan ha^-1; 3 798.37 and 5 310.64 RMB yuan ha^-1, respectively, higher than those from CK. Therefore, RD and RF complex ecological planting and breeding models can effectively decrease and control CH4 and N2O emissions, and they are two of the effective strategies to reduce greenhouse gases from rice paddy fields and contribute in alleviating global warming. Thus, their adoption is important to the environment together with their economy benefits.
文摘Two cobalt（Ⅱ） complexes 1 and 2 of Schiff bases derived from amino acids were synthesized and used for oxidation of benzyl alcohol with molecular oxygen at different conditions of pH,solvent,temperature and complex/alcohol molar ratio to optimize reaction conditions and to evaluate the catalytic efficiency of new cobalt Schiff base complexes.Under obtained optimum conditions,various alcohols were oxidized to corresponding aldehydes and ketones.
