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Sol-gel derived oxides and mixed oxides catalysts with narrow mesoporous distribution

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Science China Chemistry 2001年第4期44卷 387-397页

作者：姚楠熊国兴张玉红杨维慎 State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian China

A novel sol-gel process for preparing oxides and mixed oxides sols from precipitation and peptization process is reported in this article. Inorganic salts are used as raw materials in this study. It is found that the amount of acid has great influence on the stability and particle diameter distribution of the precursor sols. Ultrasonic treatment is used to prepare alumina sol at room temperature. The result of27Al NMR shows that there exist Al13 7+ species in the sol. By controlling the sol particles with narrow particle diameter distribution, alumina, titania and silica-alumina (SA) materials with narrow mesoporous distribution are formed by regular packing of sol particles during gelation without using any templates. The results also show that the structure and particle diameter distribution of precursor sol determine the final materials’ texture.

关键词： sol-gel mesopore oxides mixed oxides catalysts

Y-Ba-Cu-O mixed oxides for production of diphenols in liquid-solid phase

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Chinese Journal of Chemistry 1996年第6期14卷 516-524页

作者： Liu, CB Zhao, Z Yang, XG Ye, XK Wu, Y CHINESE ACAD SCI CHANGCHUN INST APPL CHEMCHANGCHUN 130022JILINPEOPLES R CHINA

Superconductor mixed oxides were often used as catalysts at higher temperature in gas phase oxidations, and considered not suitable for lower temperature reactions in the liquid-solid phase; here the catalysis of YBa2Cu3O7+/-x and Y2BaCuO5+/-x in the phenol hydroxylation at lower temperature with H2O2 as oxygen donor was studied, and found that the superconductor YBa2Cu3O7+/-x, has no catalytic activity for phenol hydroxylation, but Y2BaCuO5+/-x does, even has better catalytic activity and stability than most previously reported ones. With the studies of catalysis of other simple metal oxides and perovskite-like mixed oxides, a radical substitution mechanism is proposed and the experimental facts are explained clearly, and draw a conclusion that the perovskite-like mixed oxides with (AO)(ABO(3)) and (AO)2(ABO(3)) structure have better catalytic activity than the simple perovskite oxides with (ABO(3))(3) structure alone, and (AO) structure unit is the key for the mixed oxides to have the phenol hydroxylation activity. No pollution of this process is very important for its further industrial application.

关键词： superconductor mixed oxides phenol hydroxylation radical substitution

mixed iridium-nickel oxides supported on antimony-doped tin oxide as highly efficient and stable acidic oxygen evolution catalysts

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Materials Futures 2024年第1期3卷 165-180页

作者： Jonathan Ruiz Esquius Alec P LaGrow Haiyan Jin Zhipeng Yu Ana Araujo Rita Marques Adélio Mendes Lifeng Liu Clean Energy Cluster International Iberian Nanotechnology LaboratoryAv.Mestre JoséVeigaBraga 4715-330Portugal Carbon Science and Technology Institute INCAR-CSICFrancisco Pintado Fe 26Oviedo 33011Spain Scientific Imaging Section Okinawa Institute of Science and Technology Graduate UniversityKunigami-gunOkinawa 904-0412Japan Songshan Lake Materials Laboratory Dongguan 523808People’s Republic of China Laboratory for Process Engineering EnvironmentBiotechnology and EnergyFaculty of EngineeringUniversity of PortoRua Dr Roberto FriasPorto 4200-465Portugal Associate Laboratory in Chemical Engineering Faculty of EngineeringUniversity of PortoRua Dr Roberto FriasPorto 4200-465Portugal.

Proton exchange membrane(PEM)water electrolysis represents a promising technology for green hydrogen production,but its widespread deployment is greatly hindered by the indispensable usage of platinum group metal catalysts,especially iridium(Ir)based materials for the energy-demanding oxygen evolution reaction(OER).Herein,we report a new sequential precipitation approach to the synthesis of mixed Ir-nickel(Ni)oxy-hydroxide supported on antimony-doped tin oxide(ATO)nanoparticles(IrNiyO_(x)/ATO,20 wt.%(Ir+Ni),y=0,1,2,and 3),aiming to reduce the utilisation of scarce and precious Ir while maintaining its good acidic OER *** tested in strongly acidic electrolyte(0.1 M HClO_(4)),the optimised IrNi1Ox/ATO shows a mass activity of 1.0 mAµgIr^(−1) and a large turnover frequency of 123 s^(−1) at an overpotential of 350 mV,as well as a comparatively small Tafel slope of 50 mV dec^(−1),better than the IrOx/ATO control,particularly with a markedly reduced Ir loading of only 19.7µgIr cm^(−2).Importantly,IrNi1O_(x)/ATO also exhibits substantially better catalytic stability than other reference catalysts,able to continuously catalyse acidic OER at 10 mA cm^(−2) for 15 h without obvious *** in-situ synchrotron-based x-ray absorption spectroscopy confirmed that the Ir^(3+)/Ir^(4+)species are the active sites for the acidic ***,the performance of IrNi1Ox/ATO was also preliminarily evaluated in a membrane electrode assembly,which shows better activity and stability than other reference *** IrNi1Ox/ATO reported in this work is a promising alternative to commercial IrO_(2) based catalysts for PEM electrolysis.

关键词： mixed oxides oxygen evolution reaction polymer electrolyte membrane antimony doped tin oxide membrane electrode assembly

Moderate concentration of citric acid for the formation of LaMnO3 and LaCoO3 nano-perovskites

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Journal of Rare Earths 2013年第10期31卷 997-1002页

作者： Elham Ghiasi Azim Malekzadeh Mahnaz Ghiasi School of Chemistry Damghan University

Stoichiometric LaMnO3and LaCoO3nanoparticles were synthesized via calcination of a dried solution,containing molar ratio of La(NO3)3·6H2O/[Mn(NO3)2·4H2O or Co(NO3)2·6H2O]=1 and citric acid as disperser at temperature range of 600–900 oC for 5 *** role of organic additive concentration,which was 0.0,1.0,2.5 and 5 times of the total number of moles of the nitrate ions,was investigated on phase formation,morphology,extent of crystallization and particle size of the *** were characterized by X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM)and transmission electron microscopy(TEM)*** tendency of lanthanum ion toward manganese cation was observed to be more than to cobalt cation for the formation of LaBO3(B:Mn or Co)perovskite phase.A spongy product was formed on perovskite phase formation or in the presence of citric acid.A constructive or destructive effect was observed for the organic disperser on perovskite phase formation,which depended on mole of the citric acid.

关键词： mixed oxides LaMnO3 LaCoO3 nano-perovskite citric acid rare earths

Rugate filters prepared by rapidly alternating deposition

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Chinese Physics B 2011年第9期20卷 258-261页

作者：张俊超方明邵宇川晋云霞贺洪波 Key Laboratory of Material Science and Technology for High Power Lasers Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Graduate University of Chinese Academy of Sciences

A methodology for the fabrication of composite （Nb205）l-x（SiO2）~ thin-film rugate filters by using pulsed direct current magnetron sputtering is presented. The two materials are mixed using rapidly alternating deposition technol- ogy. The optical properties of the composite films varying with the composition of the material are studied in detail, Refractive indices between 1.50 and 2.14 can be realized in our coating system. Two designed rugate filters with a re- flection band at the wavelength of 532 nm are fabricated using an automatic deposition process. The microstructure of the rugate filter is investigated by using scanning electron microscopy. The calculated and the measured transmittance spectra axe in good agreement with each other, The causes of the slight differences between them are also analysed.

关键词： rapidly alternating deposition rugate filter magnetron sputtering mixed oxides

Moderate concentration of citric acid for the formation of LaMn03 and LaCo03 nano-perovskites

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Journal of Rare Earths 2013年第10期31卷 997-1002页

Stoichiometric LaMnO3 and LaCoO3 nanoparticles were synthesized via calcination of a dried solution, containing molar ratio of La（NO3）3＋6H20/[Mn（NO3）2-4H20 or Co（NO3）2-6H20]=1 and citric acid as disperser at temperature range of 600-900 ℃for 5 h. The role of organic additive concentration, which was 0.0, 1.0, 2.5 and 5 times of the total number of moles of the nitrate ions, was investigated on phase formation, morphology, extent of crystallization and particle size of the products. Products were characterized by X-ray diffraction （XRD）, Fourier-transform infrared spectroscopy （FT-IR）, scanning electron microscopy （SEM） and Wansmission elec- tron microscopy （TEM） analysis. The tendency of lanthanum ion toward manganese cation was observed to be more than to cobalt cation for the formation of LaBO3 （B： Mn or Co） perovskite phase. A spongy product was formed on perovskite phase formation or in the pres- ence of citric acid. A constructive or destructive effect was observed for the organic disperser on perovskite phase formation, which de- pended on mole of the citric acid.

关键词： mixed oxides LaMn03 LaCo03 nano-perovskite citric acid rare earths