The porous cubic yttrium oxides with high specific surface area were prepared by the explosive decomposition of yttrium nitrate and its complex formed with methyl salicylate. The specific surface area and properties o...The porous cubic yttrium oxides with high specific surface area were prepared by the explosive decomposition of yttrium nitrate and its complex formed with methyl salicylate. The specific surface area and properties of powders synthesized at various temperatures were characterized using BET, X-ray diffraction (XRD), infrared spectra (IR), and scanning electron microscopy (SEM). The results indicate that the highest specific surface area is found to be 65.37 m2·g -1 at the calcination temperature of 600 ℃, and then decreases to 20.33 m2·g -1 with the calcination temperature rising from 600 to 900 ℃. The powders show strong surface activity for adsorping water and carbon dioxide in air, which also decreases with the rising calcination temperature. The drop both on the surface area and surface activity of samples at higher temperatures may be due to pore-narrowing(sintering) effects.展开更多
The global energy-related CO_(2) emissions have rapidly increased as the world economy heavily relied on fossil fuels.This paper explores the pressing challenge of CO_(2) emissions and highlights the role of porous me...The global energy-related CO_(2) emissions have rapidly increased as the world economy heavily relied on fossil fuels.This paper explores the pressing challenge of CO_(2) emissions and highlights the role of porous metal oxide materials in the electrocatalytic reduction of CO_(2)(CO_(2)RR).The focus is on the development of robust and selective catalysts,particularly metal and metal-oxide-based materials.Porous metal oxides offer high surface area,enhancing the accessibility to active sites and improving reaction kinetics.The tunability of these materials allows for tailored catalytic behavior,targeting optimized reaction mechanisms for CO_(2)RR.The work also discusses the various synthesis strategies and identifies key structural and compositional features,addressing challenges like high overpotential,poor selectivity,and low stability.Based on these insights,we suggest avenues for future research on porous metal oxide materials for electrochemical CO_(2) reduction.展开更多
The rational synthesis of a two-dimensional(2D)porous aromatic framework(PAF)with a controllable growth direction remains a challenge to overcome the limitation of traditional stacked 2D materials.Herein,a step-growth...The rational synthesis of a two-dimensional(2D)porous aromatic framework(PAF)with a controllable growth direction remains a challenge to overcome the limitation of traditional stacked 2D materials.Herein,a step-growth strategy is developed to fabricate a vertically oriented nitrogen-rich porous aromatic framework on graphene oxide(V-PAF-GO)using monolayer benzidine-functionalized GO(BZ-GO)as a molecular pillar.Then,the confined Co nanoparticle(NP)catalysts are synthesized by encapsulating ultra-small Co into the slit pores of V-PAF-GO.Due to the high nitrogen content,large specific surface area,and adequate slit pores,the optimized vertical nanocomposites V-PAF-GO provide abundant anchoring sites for metal NPs,leading to ultrafine Co NPs(1.4 nm).The resultant Co/V-PAF-GO catalyst shows an extraordinary catalytic activity for ammonia borane(AB)methanolysis,yielding a turnover frequency value of 47.6 min−1 at 25°C,comparable to the most effective non-noble-metal catalysts ever reported for AB methanolysis.Experimental and density functional theory studies demonstrate that the electron-donating effect of N species of PAF positively corresponds to the low barrier in methanol molecule activation,and the cleavage of the O–H bond in CH3OH has been proven to be the rate-determining step for AB methanolysis.This work presents a versatile step-growth strategy to prepare a vertically oriented PAF on GO to solve the stacking problem of 2D materials,which will be used to fabricate other novel 2D or 2D–2D materials with controllable orientation for various applications.展开更多
Y2O3 nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently there are many studies focusing on controlling the size and morphology of Y2O3 in order to obtain better materials per...Y2O3 nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently there are many studies focusing on controlling the size and morphology of Y2O3 in order to obtain better materials performance. In present study, yttrium oxyhydroxide precursor was synthesized via a facile solvothermal process through the dissolution-recrystallization mechanism of Y2O3 raw powders in the ethylenediamine solvent, then nanosized yttrium oxide crystal was prepared from the precursor through post heat treatment process. The effects of solvothermal treatment temperature, holding time, solvent kinds and post heat treatment parameters on crystalline structure, grain shape and size of nanocrystal were investigated by XRD, TEM and TGA-DTA measurements. TEM images reveal that the morphology of product after post heat treatment at 460 ℃ for 12 h is rice-like nanocrystal. XRD shows that this product is pure cubic Y2O3 cphase. Present study reveals that high purity Y2O3 with rice-like morphology can be easily prepared with average size around 30 nm under suitable post heat treatment parameters. In addition, the effects of solvents such as water and ethanol etc. on the crystal structure and morphology were also investigated. It is suggested that dissolution-recrystallization process may be the main mechanism for the formation of nano-sized YOOH precursors under solvothermal reaction condition, and the ethylenediamine solvent is likely to play an important role in controlling the transformation process of yttria precursors to theY2O3 nanocrystal.展开更多
The 1100 ℃ isothermal oxidation behavior of Fe 23Cr 5Al alloy modified by yttrium addition was studied by means of thermogravimetric analysis, scanning electron microscopy and energy dispersive X ray analysis. Yttriu...The 1100 ℃ isothermal oxidation behavior of Fe 23Cr 5Al alloy modified by yttrium addition was studied by means of thermogravimetric analysis, scanning electron microscopy and energy dispersive X ray analysis. Yttrium was added to this alloy in the forms of metallic addition, yttrium oxide and ion implant. Cracking and spalling occurred on the convoluted scale formed on Y free alloy and exposed the substrate. A flat dense scale without spallation was formed on the yttrium alloying addition or yttrium oxide dispersion alloy. The scale adhesion was also improved by 1×10 17 Y +/cm 2 implantation. The results indicate the convoluted morphology of the scale on Fe 23Cr 5Al 0 21Ti alloy is related to the growth mechanism of the alumina scale, and the spallation of the scale is related to sulfur segregation at the scale/alloy interface. The main reason that the adhesion of alumina scale is improved by yttrium addition lies in the following. Yttrium is liable to form a stable yttrium sulfide with sulfur in the alloy and prevent sulfur interface from segregation. Another reason is that the growth mechanism of alumina scale is changed by yttrium addition.展开更多
Zirconium alloys are active in the molten state and tend to react with the mold during casting. The casting technology of zirconium is not yet well established; especially in selecting the mold materials, which are di...Zirconium alloys are active in the molten state and tend to react with the mold during casting. The casting technology of zirconium is not yet well established; especially in selecting the mold materials, which are diffi cult to determine. In the present work, the interfacial reactions between zirconium casting and casting mold were studied. The zirconium alloy was melted in a vacuum arc skull furnace and then cast into the graphite mold and ceramic mold, respectively. The zirconium casting samples were characterized using SEM, EDS and XRD with an emphasis on the chemical diffusion of elements. A reaction layer was observed at the casting surface. Chemical analysis shows that chemical elements C, O and Y from the mold are diffused into the molten zirconium, and new phases, such as ZrC, Zr3O, YO1.335 and Y6ZrO11, are formed at the surface. In addition, an end product of zirconium valve cast in a yttria mold has a compact structure and good surface quality.展开更多
We rationally designed a high performance denitration(De-NOx) catalyst based on a micrometer-sized spherical Mn–Ce–Fe–Ti(CP-SD)catalyst for selective catalytic reduction(SCR). This was prepared by a co-precipitatio...We rationally designed a high performance denitration(De-NOx) catalyst based on a micrometer-sized spherical Mn–Ce–Fe–Ti(CP-SD)catalyst for selective catalytic reduction(SCR). This was prepared by a co-precipitation and spray drying(CP-SD) method. The catalyst was systematically characterized, and its morphological structure and surface properties were identified. Compare with conventional Mn–Ce–Fe–Ti(CP) catalysts, the Mn–Ce–Fe–Ti(CP-SD) catalyst had superior surface-adsorbed oxygen leading to enhanced 'fast NH3-SCR' reaction. The asobtained Mn–Ce–Fe–Ti(CP-SD) catalyst offered excellent NO conversion and N2 selectivity of 100.0% and 84.8% at 250℃, respectively, with a gas hourly space velocity(GHSV) of 40,000 h-1. The porous micro-spherical structure provides a larger surface area and more active sites to adsorb and activate the reaction gases. In addition, the uniform distribution and strong interaction of manganese, iron, cerium, and titanium oxide species improved H2O and SO2 resistance. The results showed that the Mn–Ce–Fe–Ti(CP-SD) catalyst could be used prospectively as a denitration(De-NOx) catalyst.展开更多
Catalyst recovery is one of the most important aspects that restrict the application of Ti O_2 photocatalyst. In order to reduce restrictions and improve the photocatalytic efficiency, a hierarchical porous Ti O_2 mon...Catalyst recovery is one of the most important aspects that restrict the application of Ti O_2 photocatalyst. In order to reduce restrictions and improve the photocatalytic efficiency, a hierarchical porous Ti O_2 monolith(PTM) with well-defined macroporous and homogeneous mesoporous structure was prepared by using a sol-gel phase separation method. P123 was used as the mesoporous template and graphene oxide was applied to increase the activity and integrity of the monolithic Ti O_2. According to scanning electron microscopy and the Barrett-Joyner-Halenda measurements, PTM_3 is mainly composed of 10 nm anatase crystallines with3.6 nm mesopores and 2-8 μm macropores. Further characterization suggests carbon and nitrogen have been maintained in the PTM during calcinations so as to induce the visible light activity. The PTM with 0.07 wt%graphene oxide dosage shows high efficiency for methyl orange(MO) decolorization under both full spectrum and visible light irradiation(λ >400 nm). Besides, the monolith remains intact and has good photocatalytic stability after four cyclic experiments.展开更多
Isothermal and cyctic oxidation behaviours of pure and yttrium-implanted nickelwere studied at 1000℃ in air.Scanning electronic microscopy (SEM) and transmission electronicmicroscopy (TEM) were used to examine the mi...Isothermal and cyctic oxidation behaviours of pure and yttrium-implanted nickelwere studied at 1000℃ in air.Scanning electronic microscopy (SEM) and transmission electronicmicroscopy (TEM) were used to examine the micro-morphology and structure of oxide scalesformed on the nickel substrate.It was found that Y-implantation significantly improved the anti-oxidation ability of nickel in both isothermal and cyclic oxidizing experiments.Laser Ramanmicroscopy was also used to study the stress status of oxide scales formed on nickel with andwithout yttrium.The main reason for the improvement in anti-oxidation of nickel was that Y-implantation greatly reduced the growing speed and grain size of NiO.This fine-grained NiO oxidefilm might have better high temperature plasticity and could relieve parts of compressive stressby means of creeping,and maintained a ridge character and a relatively low internal stress level.Hence yttrium ion-implantation remarkably enhanced the adhesion of protective NiO oxide scaleformed on the nickel substrate.展开更多
Zinc phosphate coatings formed on 6061-Al alloy,after dipping in phosphating solutions containing different amounts of Y2O3(yttrium oxide) ,were studied by scanning electron microscopy(SEM) ,X-ray diffraction(XRD) and...Zinc phosphate coatings formed on 6061-Al alloy,after dipping in phosphating solutions containing different amounts of Y2O3(yttrium oxide) ,were studied by scanning electron microscopy(SEM) ,X-ray diffraction(XRD) and electrochemical measurements. Significant variations in the morphology and corrosion resistance afforded by zinc phosphate coating were especially observed as Y2O3 in phosphating solution varied from 0 to 40 mg/L. The addition of Y2O3 changed the initial potential of the interface between aluminum alloy substrate and phosphating solution and increased the number of nucleation sites. The phosphate coating thereby was less porous structure and covered the surface of aluminum alloy completely within short phosphating time. Phosphate coating was mainly composed of Zn3(PO4) 2·4H2O(hopeite) and AlPO4(aluminum phosphate) . Y2O3,as an additive of phosphatization,accelerated precipitation and refined the gain size of phosphate coating. The corrosion resistance of zinc phosphate coating in 3% NaCl solution was improved as shown by po larization measurement. In the present research,the optimal amount of Y2O3 was 10-20 mg/L,and the optimal phosphating time was 600 s.展开更多
The method for preparing yttrium oxide with large specific surface area was introduced. By means of BET, SEM, TG and DTA analysis, the effects of precipitant, stirring velocity, non-RE impurity in solution, calcinatio...The method for preparing yttrium oxide with large specific surface area was introduced. By means of BET, SEM, TG and DTA analysis, the effects of precipitant, stirring velocity, non-RE impurity in solution, calcination temperature, on the surface area were studied respectively. The Y2O3 sample with specific surface area of more than 60 m2·g-1 and L.O.I less than 1% was prepared in the suitable precipitation condition and calcinations temperature when the ammonia used as precipitant. The SEM shows that the Y2O3 prepared with large surface area is the aggregation of about 50 nm particles.展开更多
The novel composite lithium solid polymer electrolytes (SPEs) composed of polyethylene oxide (PEO) matrix and yttrium oxide (Y2O3) nanofillers were prepared by a solution casting method. The crystal morphology of the ...The novel composite lithium solid polymer electrolytes (SPEs) composed of polyethylene oxide (PEO) matrix and yttrium oxide (Y2O3) nanofillers were prepared by a solution casting method. The crystal morphology of the SPEs was characterized by polarized optical microscope (POM) and wide-angle X-ray diffraction (WAXD). The induced nucleation and steric hindrance effects of Y2O3 nanofillers result in the increased amount as well as decreased size of PEO spherulites which are closely related to the crystallinity of the SPEs. As the Y2O3 contents increase from 0 wt% to 15 wt%, the crystallinity of the SPEs decreases proportionally. The thermal, mechanical and electrical properties of the SPEs were investigated by thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA) and AC impedance method, respectively. The physical properties including thermal, mechanical and electrical performances, depending remarkably on the polymer-filler interactions between PEO and Y2O3 nanoparticles, are improved by different degrees with the increase of Y2O3 contents. The (PEO)21LiI/10 wt%Y2O3 composite SPE exhibits the optimal room-temperature ionic conductivity of 5.95×10-5 Scm-1, which satisfies the requirements of the conventional electrochromic devices.展开更多
Ce3+-doped yttrium lanthanum oxide (Y0.9La0.1)2O3 transparent ceramics is fabricated with nanopowders and sintered in H2 atmosphere. The spectral properties of Ce:(Y0.9La0.1)2O3 transparent ceramics are investigated. ...Ce3+-doped yttrium lanthanum oxide (Y0.9La0.1)2O3 transparent ceramics is fabricated with nanopowders and sintered in H2 atmosphere. The spectral properties of Ce:(Y0.9La0.1)2O3 transparent ceramics are investigated. There appear two characteristic absorption peaks of Ce3+ ions at 230 nm and 400 nm, separately. It is found that Ce3+ ions can efficiently produce emission at 384 nm from (Y0.9La0.1)2O3 transparent ceramic host, while the emission is completely quenched in Re2O3 (Re=Y, Lu, La) host materials.展开更多
The ring-opening copolymerization of adipic anhydride with propylene oxide was carried out with yttrium triflates as a catalyst. Poly(propylene adipate) could be synthesized by controlling the copolymerization conditi...The ring-opening copolymerization of adipic anhydride with propylene oxide was carried out with yttrium triflates as a catalyst. Poly(propylene adipate) could be synthesized by controlling the copolymerization conditions. The copolymerization procedure was tracked by 1H NMR analyses.展开更多
The nanometer yttrium oxides were obtained through precipitation in aqueous solution by reaction with ammonium bicarbonate. The reaction between yttrium chloride and ammonium bicarbonate, the effect of surfactants on ...The nanometer yttrium oxides were obtained through precipitation in aqueous solution by reaction with ammonium bicarbonate. The reaction between yttrium chloride and ammonium bicarbonate, the effect of surfactants on particle size and the methods of controlling agglomeration were studied. Compared to other methods, the method of controlling the agglomeration by adding surfactant is one of the best methods for controlling the agglomeration of nanometer particles in wet-chemical process. Increasing surfactants in process of precipitation deduced particle size, obtained narrow size distribution of primary particles. As for the concentration range studied, excess surfactants increased the particle size on the contrary. Characteristics of the thermal decomposition of yttrium carbonate were studied. It indicated that the approximate chemical composition of the precipitate was Y（OH）Clx（CO3） （1-x/2） ·3H2O,the cubic Y2O3 was obtained above 600℃, the specific surface and the remain chloride of nanometer Y2O3 was decreased with calcinating temperature rising. The spherical nanometer yttrium oxide was gained with primary particles<50 nm,agglomerate distribution D 50 <150 nm, BET>35 m2/g,agglomerate constant （D 50 /D BET ）<6.展开更多
Mg_(97)Zn_(1)Y_(2)alloys with high ignition temperatures were developed by adding Sr.The addition of Sr resulted in the formation of a uniform and thin Y_(2)O_(3)film.Mg–Zn–Y alloys containing at least 0.25 at.%Sr e...Mg_(97)Zn_(1)Y_(2)alloys with high ignition temperatures were developed by adding Sr.The addition of Sr resulted in the formation of a uniform and thin Y_(2)O_(3)film.Mg–Zn–Y alloys containing at least 0.25 at.%Sr exhibited ignition temperatures of 1270–1320 K.As a result of EDS measurement,Sr was found to be concentrated in the Y_(2)O_(3)film.In addition,a mixed film of MgO and Sr O formed on the outer layer in the 1.5 at.%Sr-containing Mg_(97)Zn_(1)Y_(2)alloy.These findings suggest that the uniform and thin Y_(2)O_(3)film that maintains high soundness at high temperatures was formed owing to valence control and the formation of a protective outer oxide film.展开更多
文摘The porous cubic yttrium oxides with high specific surface area were prepared by the explosive decomposition of yttrium nitrate and its complex formed with methyl salicylate. The specific surface area and properties of powders synthesized at various temperatures were characterized using BET, X-ray diffraction (XRD), infrared spectra (IR), and scanning electron microscopy (SEM). The results indicate that the highest specific surface area is found to be 65.37 m2·g -1 at the calcination temperature of 600 ℃, and then decreases to 20.33 m2·g -1 with the calcination temperature rising from 600 to 900 ℃. The powders show strong surface activity for adsorping water and carbon dioxide in air, which also decreases with the rising calcination temperature. The drop both on the surface area and surface activity of samples at higher temperatures may be due to pore-narrowing(sintering) effects.
基金funded by the National Natural Science Foundation of China,China (Nos.52272303 and 52073212)the General Program of Municipal Natural Science Foundation of Tianjin,China (Nos.17JCYBJC22700 and 17JCYBJC17000)the State Scholarship Fund of China Scholarship Council,China (Nos.201709345012 and 201706255009)。
文摘The global energy-related CO_(2) emissions have rapidly increased as the world economy heavily relied on fossil fuels.This paper explores the pressing challenge of CO_(2) emissions and highlights the role of porous metal oxide materials in the electrocatalytic reduction of CO_(2)(CO_(2)RR).The focus is on the development of robust and selective catalysts,particularly metal and metal-oxide-based materials.Porous metal oxides offer high surface area,enhancing the accessibility to active sites and improving reaction kinetics.The tunability of these materials allows for tailored catalytic behavior,targeting optimized reaction mechanisms for CO_(2)RR.The work also discusses the various synthesis strategies and identifies key structural and compositional features,addressing challenges like high overpotential,poor selectivity,and low stability.Based on these insights,we suggest avenues for future research on porous metal oxide materials for electrochemical CO_(2) reduction.
基金National Natural Science Foundation of China,Grant/Award Number:22162014 and 22162013Natural Science Foundation of Jiangxi Province of China,Grant/Award Number:20212ACB204009+1 种基金Sponsored Program for Academic and Technical Leaders of Major Disciplines of Jiangxi Province of China,Grant/Award Number:20212BCJL23059Doctoral Research Foundation Project of Tongren University,Grant/Award Number:trxyDH2204。
文摘The rational synthesis of a two-dimensional(2D)porous aromatic framework(PAF)with a controllable growth direction remains a challenge to overcome the limitation of traditional stacked 2D materials.Herein,a step-growth strategy is developed to fabricate a vertically oriented nitrogen-rich porous aromatic framework on graphene oxide(V-PAF-GO)using monolayer benzidine-functionalized GO(BZ-GO)as a molecular pillar.Then,the confined Co nanoparticle(NP)catalysts are synthesized by encapsulating ultra-small Co into the slit pores of V-PAF-GO.Due to the high nitrogen content,large specific surface area,and adequate slit pores,the optimized vertical nanocomposites V-PAF-GO provide abundant anchoring sites for metal NPs,leading to ultrafine Co NPs(1.4 nm).The resultant Co/V-PAF-GO catalyst shows an extraordinary catalytic activity for ammonia borane(AB)methanolysis,yielding a turnover frequency value of 47.6 min−1 at 25°C,comparable to the most effective non-noble-metal catalysts ever reported for AB methanolysis.Experimental and density functional theory studies demonstrate that the electron-donating effect of N species of PAF positively corresponds to the low barrier in methanol molecule activation,and the cleavage of the O–H bond in CH3OH has been proven to be the rate-determining step for AB methanolysis.This work presents a versatile step-growth strategy to prepare a vertically oriented PAF on GO to solve the stacking problem of 2D materials,which will be used to fabricate other novel 2D or 2D–2D materials with controllable orientation for various applications.
基金Project supported by SRF for ROCS, SEM (2003-14) and Science and Technology Department of Zhejiang Province (2003C11027)
文摘Y2O3 nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently there are many studies focusing on controlling the size and morphology of Y2O3 in order to obtain better materials performance. In present study, yttrium oxyhydroxide precursor was synthesized via a facile solvothermal process through the dissolution-recrystallization mechanism of Y2O3 raw powders in the ethylenediamine solvent, then nanosized yttrium oxide crystal was prepared from the precursor through post heat treatment process. The effects of solvothermal treatment temperature, holding time, solvent kinds and post heat treatment parameters on crystalline structure, grain shape and size of nanocrystal were investigated by XRD, TEM and TGA-DTA measurements. TEM images reveal that the morphology of product after post heat treatment at 460 ℃ for 12 h is rice-like nanocrystal. XRD shows that this product is pure cubic Y2O3 cphase. Present study reveals that high purity Y2O3 with rice-like morphology can be easily prepared with average size around 30 nm under suitable post heat treatment parameters. In addition, the effects of solvents such as water and ethanol etc. on the crystal structure and morphology were also investigated. It is suggested that dissolution-recrystallization process may be the main mechanism for the formation of nano-sized YOOH precursors under solvothermal reaction condition, and the ethylenediamine solvent is likely to play an important role in controlling the transformation process of yttria precursors to theY2O3 nanocrystal.
文摘The 1100 ℃ isothermal oxidation behavior of Fe 23Cr 5Al alloy modified by yttrium addition was studied by means of thermogravimetric analysis, scanning electron microscopy and energy dispersive X ray analysis. Yttrium was added to this alloy in the forms of metallic addition, yttrium oxide and ion implant. Cracking and spalling occurred on the convoluted scale formed on Y free alloy and exposed the substrate. A flat dense scale without spallation was formed on the yttrium alloying addition or yttrium oxide dispersion alloy. The scale adhesion was also improved by 1×10 17 Y +/cm 2 implantation. The results indicate the convoluted morphology of the scale on Fe 23Cr 5Al 0 21Ti alloy is related to the growth mechanism of the alumina scale, and the spallation of the scale is related to sulfur segregation at the scale/alloy interface. The main reason that the adhesion of alumina scale is improved by yttrium addition lies in the following. Yttrium is liable to form a stable yttrium sulfide with sulfur in the alloy and prevent sulfur interface from segregation. Another reason is that the growth mechanism of alumina scale is changed by yttrium addition.
基金supported by the National Natural Science Foundation of China(No.51075285) the Provincial Natural Science Foundation of Liaoning in China(No.20102222)
文摘Zirconium alloys are active in the molten state and tend to react with the mold during casting. The casting technology of zirconium is not yet well established; especially in selecting the mold materials, which are diffi cult to determine. In the present work, the interfacial reactions between zirconium casting and casting mold were studied. The zirconium alloy was melted in a vacuum arc skull furnace and then cast into the graphite mold and ceramic mold, respectively. The zirconium casting samples were characterized using SEM, EDS and XRD with an emphasis on the chemical diffusion of elements. A reaction layer was observed at the casting surface. Chemical analysis shows that chemical elements C, O and Y from the mold are diffused into the molten zirconium, and new phases, such as ZrC, Zr3O, YO1.335 and Y6ZrO11, are formed at the surface. In addition, an end product of zirconium valve cast in a yttria mold has a compact structure and good surface quality.
基金supported by Major Scientific and Technological Project of Bingtuan (No.2018AA002)the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT_15R46)
文摘We rationally designed a high performance denitration(De-NOx) catalyst based on a micrometer-sized spherical Mn–Ce–Fe–Ti(CP-SD)catalyst for selective catalytic reduction(SCR). This was prepared by a co-precipitation and spray drying(CP-SD) method. The catalyst was systematically characterized, and its morphological structure and surface properties were identified. Compare with conventional Mn–Ce–Fe–Ti(CP) catalysts, the Mn–Ce–Fe–Ti(CP-SD) catalyst had superior surface-adsorbed oxygen leading to enhanced 'fast NH3-SCR' reaction. The asobtained Mn–Ce–Fe–Ti(CP-SD) catalyst offered excellent NO conversion and N2 selectivity of 100.0% and 84.8% at 250℃, respectively, with a gas hourly space velocity(GHSV) of 40,000 h-1. The porous micro-spherical structure provides a larger surface area and more active sites to adsorb and activate the reaction gases. In addition, the uniform distribution and strong interaction of manganese, iron, cerium, and titanium oxide species improved H2O and SO2 resistance. The results showed that the Mn–Ce–Fe–Ti(CP-SD) catalyst could be used prospectively as a denitration(De-NOx) catalyst.
基金financially supported by the National Natural Science Foundation of China (No. 20907031)
文摘Catalyst recovery is one of the most important aspects that restrict the application of Ti O_2 photocatalyst. In order to reduce restrictions and improve the photocatalytic efficiency, a hierarchical porous Ti O_2 monolith(PTM) with well-defined macroporous and homogeneous mesoporous structure was prepared by using a sol-gel phase separation method. P123 was used as the mesoporous template and graphene oxide was applied to increase the activity and integrity of the monolithic Ti O_2. According to scanning electron microscopy and the Barrett-Joyner-Halenda measurements, PTM_3 is mainly composed of 10 nm anatase crystallines with3.6 nm mesopores and 2-8 μm macropores. Further characterization suggests carbon and nitrogen have been maintained in the PTM during calcinations so as to induce the visible light activity. The PTM with 0.07 wt%graphene oxide dosage shows high efficiency for methyl orange(MO) decolorization under both full spectrum and visible light irradiation(λ >400 nm). Besides, the monolith remains intact and has good photocatalytic stability after four cyclic experiments.
基金National Natural Science Foundation of China(No.29231011)National Natural Science Foundation of Colombia(No.M018327)
文摘Isothermal and cyctic oxidation behaviours of pure and yttrium-implanted nickelwere studied at 1000℃ in air.Scanning electronic microscopy (SEM) and transmission electronicmicroscopy (TEM) were used to examine the micro-morphology and structure of oxide scalesformed on the nickel substrate.It was found that Y-implantation significantly improved the anti-oxidation ability of nickel in both isothermal and cyclic oxidizing experiments.Laser Ramanmicroscopy was also used to study the stress status of oxide scales formed on nickel with andwithout yttrium.The main reason for the improvement in anti-oxidation of nickel was that Y-implantation greatly reduced the growing speed and grain size of NiO.This fine-grained NiO oxidefilm might have better high temperature plasticity and could relieve parts of compressive stressby means of creeping,and maintained a ridge character and a relatively low internal stress level.Hence yttrium ion-implantation remarkably enhanced the adhesion of protective NiO oxide scaleformed on the nickel substrate.
基金supported by the Natural Science Foundation of Henan Province (200510476009)
文摘Zinc phosphate coatings formed on 6061-Al alloy,after dipping in phosphating solutions containing different amounts of Y2O3(yttrium oxide) ,were studied by scanning electron microscopy(SEM) ,X-ray diffraction(XRD) and electrochemical measurements. Significant variations in the morphology and corrosion resistance afforded by zinc phosphate coating were especially observed as Y2O3 in phosphating solution varied from 0 to 40 mg/L. The addition of Y2O3 changed the initial potential of the interface between aluminum alloy substrate and phosphating solution and increased the number of nucleation sites. The phosphate coating thereby was less porous structure and covered the surface of aluminum alloy completely within short phosphating time. Phosphate coating was mainly composed of Zn3(PO4) 2·4H2O(hopeite) and AlPO4(aluminum phosphate) . Y2O3,as an additive of phosphatization,accelerated precipitation and refined the gain size of phosphate coating. The corrosion resistance of zinc phosphate coating in 3% NaCl solution was improved as shown by po larization measurement. In the present research,the optimal amount of Y2O3 was 10-20 mg/L,and the optimal phosphating time was 600 s.
文摘The method for preparing yttrium oxide with large specific surface area was introduced. By means of BET, SEM, TG and DTA analysis, the effects of precipitant, stirring velocity, non-RE impurity in solution, calcination temperature, on the surface area were studied respectively. The Y2O3 sample with specific surface area of more than 60 m2·g-1 and L.O.I less than 1% was prepared in the suitable precipitation condition and calcinations temperature when the ammonia used as precipitant. The SEM shows that the Y2O3 prepared with large surface area is the aggregation of about 50 nm particles.
基金Funded by the National Natural Science Foundation of China (No. 51003082)the Key Project of Science and Technology Research of Ministry of Education (No. 208089)+2 种基金the Educational Commission of Hubei Province (No.Q20101606)the Young Outstanding Talent Foundation of Hubei Province (No.2008CDB261)the Natural Science Foundation of Hubei Province (No. 2007ABA075)
文摘The novel composite lithium solid polymer electrolytes (SPEs) composed of polyethylene oxide (PEO) matrix and yttrium oxide (Y2O3) nanofillers were prepared by a solution casting method. The crystal morphology of the SPEs was characterized by polarized optical microscope (POM) and wide-angle X-ray diffraction (WAXD). The induced nucleation and steric hindrance effects of Y2O3 nanofillers result in the increased amount as well as decreased size of PEO spherulites which are closely related to the crystallinity of the SPEs. As the Y2O3 contents increase from 0 wt% to 15 wt%, the crystallinity of the SPEs decreases proportionally. The thermal, mechanical and electrical properties of the SPEs were investigated by thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA) and AC impedance method, respectively. The physical properties including thermal, mechanical and electrical performances, depending remarkably on the polymer-filler interactions between PEO and Y2O3 nanoparticles, are improved by different degrees with the increase of Y2O3 contents. The (PEO)21LiI/10 wt%Y2O3 composite SPE exhibits the optimal room-temperature ionic conductivity of 5.95×10-5 Scm-1, which satisfies the requirements of the conventional electrochromic devices.
基金supported by the National Natural Science Foundation of China (Grant No. 60578041)the Shanghai Leading Academic Disciplines (Grant No. S30107)
文摘Ce3+-doped yttrium lanthanum oxide (Y0.9La0.1)2O3 transparent ceramics is fabricated with nanopowders and sintered in H2 atmosphere. The spectral properties of Ce:(Y0.9La0.1)2O3 transparent ceramics are investigated. There appear two characteristic absorption peaks of Ce3+ ions at 230 nm and 400 nm, separately. It is found that Ce3+ ions can efficiently produce emission at 384 nm from (Y0.9La0.1)2O3 transparent ceramic host, while the emission is completely quenched in Re2O3 (Re=Y, Lu, La) host materials.
基金Supported by the National Natural Science Foundation of China(Nos.20704036, Key Program 20434020)the State Basic Research Projects of China(No.2005CB623802)
文摘The ring-opening copolymerization of adipic anhydride with propylene oxide was carried out with yttrium triflates as a catalyst. Poly(propylene adipate) could be synthesized by controlling the copolymerization conditions. The copolymerization procedure was tracked by 1H NMR analyses.
基金Project supported by key project of science and technology research of guangdong province(2002A1070108)
文摘The nanometer yttrium oxides were obtained through precipitation in aqueous solution by reaction with ammonium bicarbonate. The reaction between yttrium chloride and ammonium bicarbonate, the effect of surfactants on particle size and the methods of controlling agglomeration were studied. Compared to other methods, the method of controlling the agglomeration by adding surfactant is one of the best methods for controlling the agglomeration of nanometer particles in wet-chemical process. Increasing surfactants in process of precipitation deduced particle size, obtained narrow size distribution of primary particles. As for the concentration range studied, excess surfactants increased the particle size on the contrary. Characteristics of the thermal decomposition of yttrium carbonate were studied. It indicated that the approximate chemical composition of the precipitate was Y（OH）Clx（CO3） （1-x/2） ·3H2O,the cubic Y2O3 was obtained above 600℃, the specific surface and the remain chloride of nanometer Y2O3 was decreased with calcinating temperature rising. The spherical nanometer yttrium oxide was gained with primary particles<50 nm,agglomerate distribution D 50 <150 nm, BET>35 m2/g,agglomerate constant （D 50 /D BET ）<6.
基金supported by Grants-in-Aid for Scientific Research C(JP21K04693)from JSPS,Japan。
文摘Mg_(97)Zn_(1)Y_(2)alloys with high ignition temperatures were developed by adding Sr.The addition of Sr resulted in the formation of a uniform and thin Y_(2)O_(3)film.Mg–Zn–Y alloys containing at least 0.25 at.%Sr exhibited ignition temperatures of 1270–1320 K.As a result of EDS measurement,Sr was found to be concentrated in the Y_(2)O_(3)film.In addition,a mixed film of MgO and Sr O formed on the outer layer in the 1.5 at.%Sr-containing Mg_(97)Zn_(1)Y_(2)alloy.These findings suggest that the uniform and thin Y_(2)O_(3)film that maintains high soundness at high temperatures was formed owing to valence control and the formation of a protective outer oxide film.
