Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. S...Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. SnO2-NS possesses a mesoporous structure and has a higher surface area, larger pore volume, and more active species than SnO2-NP, and shows improved activity. In contrast, although SnO2-NR＋NP has only a slightly higher surface area and pore volume, and slightly more active surface oxygen species than SnO2-NP, it has more exposed active （110） facets, which is the reason for its improved oxidation activity. Water vapor has only a reversible and weak influence on SnO2-NS, therefore it is a potential catalyst for emission control processes.展开更多
气氛环境下原位研究催化剂的烧结行为,能够为理解催化剂在预处理以及反应条件下的烧结机理和高稳定催化剂的设计提供重要的实验依据。本文以Au/CeO_(2)模型纳米催化剂为研究对象,利用环境透射电子显微镜原位观察其在O_(2)与CO气氛下的...气氛环境下原位研究催化剂的烧结行为,能够为理解催化剂在预处理以及反应条件下的烧结机理和高稳定催化剂的设计提供重要的实验依据。本文以Au/CeO_(2)模型纳米催化剂为研究对象,利用环境透射电子显微镜原位观察其在O_(2)与CO气氛下的高温动态烧结过程。实验发现,负载在CeO_(2)上的Au纳米颗粒在O_(2)与CO气氛环境中表现出不同的烧结行为,其在O_(2)气氛下具有较高的烧结速度,同时存在颗粒迁移与聚集长大(particle migration and coalescence,PMC)和奥斯特瓦尔德熟化(Ostwald ripening,OR)两种烧结过程;在CO气氛下烧结速度较慢,烧结过程以OR为主。对比不同气氛环境下烧结后催化剂的表面结构可知,CO增加了CeO_(2)表面台阶的数量以及表面氧空位浓度,增强了载体对Au颗粒的锚定作用,从而提升Au/CeO_(2)催化剂的稳定性。展开更多
High-purity(99%)carbon nanocoils(CNCs)have been synthesized by using porousα-Fe2O3/SnO2 catalyst.The yield of CNCs reaches 9,098%after a 6 h growth.This value is much higher than the previously reported data,indicati...High-purity(99%)carbon nanocoils(CNCs)have been synthesized by using porousα-Fe2O3/SnO2 catalyst.The yield of CNCs reaches 9,098%after a 6 h growth.This value is much higher than the previously reported data,indicating that this method is promising to synthesize high-purity CNCs on a large scale.It is considered that an appropriate proportion of Fe and Sn,proper particle size distribution,and a loose-porous aggregate structure of the catalyst are the key points to the high-purity growth of CNCs.Benefiting from the high-purity preparation,a CNC Buckypaper was successfully prepared and the electrical,mechanical,and electrochemical properties were investigated comprehensively.Furthermore,as one of the practical applications,the CNC Buckypaper was successfully utilized as an efficient adsorbent for the removal of methylene blue dye from wastewater with an adsorption efficiency of 90.9%.This study provides a facile and economical route for preparing high-purity CNCs,which is suitable for large-quantity production.Furthermore,the fabrication of macroscopic CNC Buckypaper provides promising alternative of adsorbent or other practical applications.展开更多
Au/FeOx-TiO2,prepared by deposition-precipitation method,is an efficient and stable catalyst for the liquid phase selective hydrogenation of phthalic anhydride to phthalide under mild reaction conditions.
A series of three‐dimensionally ordered macroporous(3DOM)SnO2‐based catalysts modified by the cations Ce4+,Mn3+,and Cu2+have been prepared by using a colloidal crystal templating method and tested for soot combustio...A series of three‐dimensionally ordered macroporous(3DOM)SnO2‐based catalysts modified by the cations Ce4+,Mn3+,and Cu2+have been prepared by using a colloidal crystal templating method and tested for soot combustion under loose contact condition.XRD and STEM mapping results confirm that all the secondary metal cations have entered the lattice matrix of tetragonal rutile SnO2 to form non‐continuous solid solutions,thus impeding crystallization and improving the surface areas and pore volumes of the modified catalysts.In comparison with regular SnO2 nanoparticles,the 3DOM SnO2 displays evidently improved activity,testifying that the formation of the 3DOM structure can anchor the soot particulates in the macro‐pores,which ensures that the contact of the soot particles with the active sites on the 3DOM skeleton is more easily formed,thus benefiting the target reaction.With the incorporation of the secondary metal cations,the activity of the catalyst can be further improved due to the formation of more abundant mobile oxygen species.In summary,these effects are believed to be the major factors responsible for the activity of the catalyst.展开更多
We examined the water adsorption and dissociation on ceria surfaces as well as ceria‐supported Au single‐atom catalysts using density functional theory calculations.Molecular and dissociative water were observed to ...We examined the water adsorption and dissociation on ceria surfaces as well as ceria‐supported Au single‐atom catalysts using density functional theory calculations.Molecular and dissociative water were observed to coexist on clean CeO2and reduced Au1/CeO2?x surfaces because of the small difference in adsorption energies,whereas the presence of dissociative water was highly favorable on reduced CeO2?x and clean Au1/CeO2surfaces.Positively charged Au single atoms on the ceria surface not only provided activation sites for water adsorption but also facilitated water dissociation by weakening the intramolecular O-H bonds.In contrast,negatively charged Au single atoms were not reactive for water adsorption because of the saturation of Au5d and6s electron shells.This work provides a fundamental understanding of the interaction between water and single‐atom Au catalysts.展开更多
Flower-liked SnO_2 nanorods were prepared by a hydrothermal method.The sensors were fabricated using SnO_2 nanorods adsorption of Au nanoparticles through sputtering deposition.We found that the loading of a small amo...Flower-liked SnO_2 nanorods were prepared by a hydrothermal method.The sensors were fabricated using SnO_2 nanorods adsorption of Au nanoparticles through sputtering deposition.We found that the loading of a small amount of Au nanoparticles on the surface of SnO_2 nanorods can effectively enhance and functionalize the gas sensing performance of SnO_2 nanorods,which due to the Au adsorption make the surface-depletion effect more pronounced.Such enhanced surface depletion increases the sensitivity,lowers the operation temperature and decreases the response time.展开更多
Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were exa...Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were examined after separate treatment in CO＋O2 or CO2 ＋O2 .Furthermore,in situ FT-IR studies were performed to investigate the species on the surface when CO or CO＋O2 or CO2 ＋O2 was selected separately as adsorption gas.The results showed that Au/Al2O3 catalyst exhibited very high initial activity,but the catalytic activity was found to decrease gradually during CO oxidation with time on stream.And also,the activity of the catalyst declined after treatment in CO＋O2 or CO2 ＋O2 .The formation and accumulation of carbonate-like species during CO oxidation or treatment in CO＋O2 or CO2 ＋O2 might be mainly responsible for the activity decrease,which was reversible.展开更多
以 Sn Cl4· Ti( OBu) 4、氨水、乙醇为原料 ,采用活性层包覆法 ,制备出 Ti O2 / Sn O2 复合光催化剂 ,并用IR、XRD、TEM和 BET等手段对样品进行了表征 .研究其对有机磷农药敌敌畏的光催化降解效果 ,与单一半导体催化剂 Sn O2 、Ti ...以 Sn Cl4· Ti( OBu) 4、氨水、乙醇为原料 ,采用活性层包覆法 ,制备出 Ti O2 / Sn O2 复合光催化剂 ,并用IR、XRD、TEM和 BET等手段对样品进行了表征 .研究其对有机磷农药敌敌畏的光催化降解效果 ,与单一半导体催化剂 Sn O2 、Ti O2 做了简单对比 .结果表明 :所制 Ti O2 / Sn O2 样品为包覆型结构 ,由锐钛矿型 Ti O2 金红石型 Sn O2 组成 ,与 Sn O2 及 Ti O2 晶体粉末相比所制 Ti O2 / Sn O2 包覆粒子光催化活性得到明显提高 .展开更多
基金supported by the National Natural Science Foundation of China (21263015)the Education Department of Jiangxi Province (KJLD14005)the Natural Science Foundation of Jiangxi Province(20151BBE50006,20122BAB203009)~~
文摘Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. SnO2-NS possesses a mesoporous structure and has a higher surface area, larger pore volume, and more active species than SnO2-NP, and shows improved activity. In contrast, although SnO2-NR＋NP has only a slightly higher surface area and pore volume, and slightly more active surface oxygen species than SnO2-NP, it has more exposed active （110） facets, which is the reason for its improved oxidation activity. Water vapor has only a reversible and weak influence on SnO2-NS, therefore it is a potential catalyst for emission control processes.
文摘气氛环境下原位研究催化剂的烧结行为,能够为理解催化剂在预处理以及反应条件下的烧结机理和高稳定催化剂的设计提供重要的实验依据。本文以Au/CeO_(2)模型纳米催化剂为研究对象,利用环境透射电子显微镜原位观察其在O_(2)与CO气氛下的高温动态烧结过程。实验发现,负载在CeO_(2)上的Au纳米颗粒在O_(2)与CO气氛环境中表现出不同的烧结行为,其在O_(2)气氛下具有较高的烧结速度,同时存在颗粒迁移与聚集长大(particle migration and coalescence,PMC)和奥斯特瓦尔德熟化(Ostwald ripening,OR)两种烧结过程;在CO气氛下烧结速度较慢,烧结过程以OR为主。对比不同气氛环境下烧结后催化剂的表面结构可知,CO增加了CeO_(2)表面台阶的数量以及表面氧空位浓度,增强了载体对Au颗粒的锚定作用,从而提升Au/CeO_(2)催化剂的稳定性。
基金financially supported by the National Natural Science Foundation of China(Nos.51661145025,51972039,and 51803018)
文摘High-purity(99%)carbon nanocoils(CNCs)have been synthesized by using porousα-Fe2O3/SnO2 catalyst.The yield of CNCs reaches 9,098%after a 6 h growth.This value is much higher than the previously reported data,indicating that this method is promising to synthesize high-purity CNCs on a large scale.It is considered that an appropriate proportion of Fe and Sn,proper particle size distribution,and a loose-porous aggregate structure of the catalyst are the key points to the high-purity growth of CNCs.Benefiting from the high-purity preparation,a CNC Buckypaper was successfully prepared and the electrical,mechanical,and electrochemical properties were investigated comprehensively.Furthermore,as one of the practical applications,the CNC Buckypaper was successfully utilized as an efficient adsorbent for the removal of methylene blue dye from wastewater with an adsorption efficiency of 90.9%.This study provides a facile and economical route for preparing high-purity CNCs,which is suitable for large-quantity production.Furthermore,the fabrication of macroscopic CNC Buckypaper provides promising alternative of adsorbent or other practical applications.
基金support provided by Zhejiang Provincial Natural Science Foundation of China(No.Y405108)the Department of Education of Zhejiang Province of China(No.20051409)
文摘Au/FeOx-TiO2,prepared by deposition-precipitation method,is an efficient and stable catalyst for the liquid phase selective hydrogenation of phthalic anhydride to phthalide under mild reaction conditions.
基金the Natural Science Foundation of China(21567016,21503106)the Natural Science Foundation of Jiangxi Province(20171BAB213013)+3 种基金the Education Department Foundation of Jiangxi Province(KJLD14005)National Key Research and Development Program of China(2016YFC0209302)the Innovation Fund Designated for Graduate Students of Jiangxi Province(YC2015-B017)the Innovation Fund Designated for Undergraduate Students of China(201701035)~~
文摘A series of three‐dimensionally ordered macroporous(3DOM)SnO2‐based catalysts modified by the cations Ce4+,Mn3+,and Cu2+have been prepared by using a colloidal crystal templating method and tested for soot combustion under loose contact condition.XRD and STEM mapping results confirm that all the secondary metal cations have entered the lattice matrix of tetragonal rutile SnO2 to form non‐continuous solid solutions,thus impeding crystallization and improving the surface areas and pore volumes of the modified catalysts.In comparison with regular SnO2 nanoparticles,the 3DOM SnO2 displays evidently improved activity,testifying that the formation of the 3DOM structure can anchor the soot particulates in the macro‐pores,which ensures that the contact of the soot particles with the active sites on the 3DOM skeleton is more easily formed,thus benefiting the target reaction.With the incorporation of the secondary metal cations,the activity of the catalyst can be further improved due to the formation of more abundant mobile oxygen species.In summary,these effects are believed to be the major factors responsible for the activity of the catalyst.
基金supported by the National Natural Science Foundation of China(21590792,91645203 and 21521091)~~
文摘We examined the water adsorption and dissociation on ceria surfaces as well as ceria‐supported Au single‐atom catalysts using density functional theory calculations.Molecular and dissociative water were observed to coexist on clean CeO2and reduced Au1/CeO2?x surfaces because of the small difference in adsorption energies,whereas the presence of dissociative water was highly favorable on reduced CeO2?x and clean Au1/CeO2surfaces.Positively charged Au single atoms on the ceria surface not only provided activation sites for water adsorption but also facilitated water dissociation by weakening the intramolecular O-H bonds.In contrast,negatively charged Au single atoms were not reactive for water adsorption because of the saturation of Au5d and6s electron shells.This work provides a fundamental understanding of the interaction between water and single‐atom Au catalysts.
文摘Flower-liked SnO_2 nanorods were prepared by a hydrothermal method.The sensors were fabricated using SnO_2 nanorods adsorption of Au nanoparticles through sputtering deposition.We found that the loading of a small amount of Au nanoparticles on the surface of SnO_2 nanorods can effectively enhance and functionalize the gas sensing performance of SnO_2 nanorods,which due to the Au adsorption make the surface-depletion effect more pronounced.Such enhanced surface depletion increases the sensitivity,lowers the operation temperature and decreases the response time.
基金supported by the Science and Research Reward Fund Program of Shandong Excellent Young Scientist of China (2007BS04033)
文摘Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were examined after separate treatment in CO＋O2 or CO2 ＋O2 .Furthermore,in situ FT-IR studies were performed to investigate the species on the surface when CO or CO＋O2 or CO2 ＋O2 was selected separately as adsorption gas.The results showed that Au/Al2O3 catalyst exhibited very high initial activity,but the catalytic activity was found to decrease gradually during CO oxidation with time on stream.And also,the activity of the catalyst declined after treatment in CO＋O2 or CO2 ＋O2 .The formation and accumulation of carbonate-like species during CO oxidation or treatment in CO＋O2 or CO2 ＋O2 might be mainly responsible for the activity decrease,which was reversible.
文摘以 Sn Cl4· Ti( OBu) 4、氨水、乙醇为原料 ,采用活性层包覆法 ,制备出 Ti O2 / Sn O2 复合光催化剂 ,并用IR、XRD、TEM和 BET等手段对样品进行了表征 .研究其对有机磷农药敌敌畏的光催化降解效果 ,与单一半导体催化剂 Sn O2 、Ti O2 做了简单对比 .结果表明 :所制 Ti O2 / Sn O2 样品为包覆型结构 ,由锐钛矿型 Ti O2 金红石型 Sn O2 组成 ,与 Sn O2 及 Ti O2 晶体粉末相比所制 Ti O2 / Sn O2 包覆粒子光催化活性得到明显提高 .
