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Experimental design for optimization of 4-nitrophenol reduction by green synthesized CeO2/g-C3N4/Ag catalyst using response surface methodology 认领 引用 被引量：4
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作者 Dephan Pinheiro K.R.Sunaja Devi +3 位作者 Ajay Jose Kashinathan Karthik Sankaran Sugunan Mothi Krishna Mohan 《Journal of Rare Earths》 SCIE EI CAS CSCD 2020年第11期1171-1177,I0001,共7页
In this study,the enhancement of catalytic activity of ceria when modified with co-catalysts such as graphitic carbon nitride and silver was establishe d.The material was synthe sized using phytogenic combustion metho... In this study,the enhancement of catalytic activity of ceria when modified with co-catalysts such as graphitic carbon nitride and silver was establishe d.The material was synthe sized using phytogenic combustion method,a green alternative to the traditional preparative routes.The catalyst was characterized using XRD,FTIR,SEM,EDX,XPS and TEM techniques.The synergistic effect of the composite CeO2/g-C3 N4/Ag was tested for catalytic reduction of 4-nitrophenol in the prese nce of sodium borohydride.The reaction was carried out at room tempe rature without any light source or exte rnal stirring.The individual and combined effects of four parameters,viz.,concentration of 4-NP,amount of catalyst,amount of NaBH4 and time for the reduction of reduction 4-NP were investigated using Box-Behnken design of response surface methodology(RSM).This statistical model was used to optimize the reaction conditions for maximum reduction of 4-NP.The optimum conditions for the reduction reaction are found to be 0.01 mmol/L 4-NP,15 mg catalyst,20 mg NaBH4 and 13.7 min time interval. 展开更多
关键词 CeO2/g-C3N4/Ag 4-Nitrophenol Box-Behnken design Response surface methodology Heterogeneous catalysis Rare earths
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Growth mechanism of palladium clusters on rutile TiO_2 (110) surface 认领 引用 被引量：3
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作者 Weina Zhao Huaxiang Lin +3 位作者 Yi Li Yongfan Zhang Xin Huang Wenkai Chen 《Journal of Natural Gas Chemistry》 CSCD 2012年第5期544-555,共12页
Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for ... Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for Pd n （n=1-5） clusters adsorbed on TiO2 （110） surface based on DFT-GGA calculations utilizing periodic supercell models.A single Pd adatom on the defect-free surface prefers to adsorb at a hollow site bridging a protruded oxygen and a five-fold titanium atom along the [110] direction,while Pd dimer is located on the channels with the Pd-Pd bond parallel to the surface.According to the transition states （TSs） search,the adsorbed Pd trimer tends to triangular growth mode,rather than linear mode,while the Pd4 and Pd5 clusters prefer three-dimensional （3D） models.However,the oxygen vacancy has almost no influence on the promotion of Pd n cluster nucleation.Additionally,of particular significance is that the Pd-TiO2 interaction is the main driving force at the beginning of Pd nucleation,whereas the Pd-Pd interaction gets down to control the growth process of Pd cluster as the cluster gets larger.It is hoped that our theoretical study would shed light on further designing high-performance TiO2 supported Pd-based catalysts. 展开更多
关键词 density functional theory TiO2 （110） surface palladium cluster adsorption
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Role of Surface Adsorption in Fast Oxygen Storage/Release of CeO_2-ZrO_2 Mixed Oxides 认领 引用 被引量：1
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作者 吴晓东 梁清 +1 位作者 吴筱笛 翁端 《Journal of Rare Earths》 SCIE EI CAS 2007年第4期416-421,共6页
Four kinds of CeO2-ZrO2 mixed oxides, i.e., a physical mixture of ceria and zirconia （CZP）, zirconia-coated ceria （ZCC）, ceria-coated zirconia （CCZ） and a chemical mixture of celia and zirconia （CZC）, were pre... Four kinds of CeO2-ZrO2 mixed oxides, i.e., a physical mixture of ceria and zirconia （CZP）, zirconia-coated ceria （ZCC）, ceria-coated zirconia （CCZ） and a chemical mixture of celia and zirconia （CZC）, were prepared. The oxygen storage capacity （OSC） measurements at 500℃ were performed under transient and stationary reaction conditions. All the curves of CO2 evolution during CO-O2 cycles presented a bimodal shape. The fast peak was primarily the result of the reaction of CO with the oxygen from the oxides, which was mainly determined by the nature of the material The sec- ond peak was mostly related to the CO2 adsorption behavior and was highly influenced by the surface area and the number of surface active sites. As a result, OSC activity of the samples followed in the order of CZC 〉 CCZ 〉 ZCC=CZP. 展开更多
关键词 CeO2-ZrO2 microstructure surface properties oxygen storage capacity rare earths
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Theoretical Study on the Structural and Electronic Properties of the Reduced SnO_2 (110) Surface 认领 引用
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作者 ZHANG Yong-Fan LIN Wei WANG Qi-Wei LI Yi LI Jun-Qian 《Chinese Journal of Structural Chemistry》 SCIE CAS 北大核心 2007年第5期606-612,共7页
The reduced SnO2（110） surface has been investigated by using first-principles method with a slab model. By examining the vacancy formation energy of three kinds of reduced SnO2（110） surfaces, the most energeticall... The reduced SnO2（110） surface has been investigated by using first-principles method with a slab model. By examining the vacancy formation energy of three kinds of reduced SnO2（110） surfaces, the most energetically favorable defect surface is confirmed to be the surface with the coexistence of bridging and in-plane oxygen vacancies, which is different with the traditional model by only removing bridging oxygen. The results of band structure calculations indicate that the electronic structure of this defect surface is similar to the SnO surface. 展开更多
关键词 SnO2（110） surface band structure defect state
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Surface Chemistry and Photochemistry of Cyclohexane on Rutile TiO2(110) 认领 引用 被引量：1
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作者 Wenyuan Wang Longxia Wu +3 位作者 Cong Fu Hong Xu Zongfang Wu Weixin Huang 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2024年第5期614-618,I0099,I0100,共5页
Cyclohexane is a high-valued chemical receivingsignificant interest in liquid hydrogen storage technology.TiO2-based catalysts show high performance in the photocatalytic dehydrogenation of cyclohexane under mild c... Cyclohexane is a high-valued chemical receivingsignificant interest in liquid hydrogen storage technology.TiO2-based catalysts show high performance in the photocatalytic dehydrogenation of cyclohexane under mild conditions,but the detailed reaction mechanism is not well understood.With the surface science approaches,we have studied the adsorption and surface chemistry of cyclohexane on rutile TiO2(110).The thermal desorption spectroscopy and X-ray photoelectron spectroscopy results both demonstrate the molecular adsorption of cyclohexane on rutile TiO2(110).Upon the UV Hg light irradiation,photodesorption of cyclohexane occurs from both the chemisorbed monolayer and the multilayer.No decomposition nor dehydrogenation of cyclohexane occurs on rutile TiO2(110).These results deepen the fundamental understanding of the surface chemistry of cyclohexane on the TiO2 surface. 展开更多
关键词 Surface chemistry Rutile TiO2(110) Photocatalytic desorption Cyclohexane
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First-Principles Study of Pd Single-Atom Catalysis to Hydrogen Desorption Reactions on MgH2(110) Surface 认领 引用 被引量：1
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作者 Xin-xing Wu Wei Hu 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2019年第3期319-326,I0001,共8页
MgH2 is a promising and popular hydrogen storage material.In this work,the hydrogen desorption reactions of a single Pd atom adsorbed MgH2(110)surface are investigated by using first-principles density functional theo... MgH2 is a promising and popular hydrogen storage material.In this work,the hydrogen desorption reactions of a single Pd atom adsorbed MgH2(110)surface are investigated by using first-principles density functional theory calculations.We find that a single Pd atom adsorbed on the MgH2(110)surface can significantly lower the energy barrier of the hydrogen desorption reactions from 1.802 eV for pure MgH2(110)surface to 1.154 eV for Pd adsorbed MgH2(110)surface,indicating a strong Pd single-atom catalytic effect on the hydrogen desorption reactions.Furthermore,the Pd single-atom catalysis significantly reduces the hydrogen desorption temperature from 573K to 367K,which makes the hydrogen desorption reactions occur more easily and quickly on the MgH2(110)surface.We also discuss the microscopic process of the hydrogen desorption reactions through the reverse process of hydrogen spillover mechanism on the MgH2(110)surface.This study shows that Pd/MgH2 thin films can be used as good hydrogen storage materials in future experiments. 展开更多
关键词 Hydrogen storage MgH2(110)surface Pd single-atom catalysis Hydrogen desorption reaction
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Effects of Surface Defects on Adsorption of CO and Methyl Groups on Rutile TiO2(110) 认领 引用
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作者 Deng-fang Tang Xiao Chen +1 位作者 Qing Guo Wen-shao Yang 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2021年第3期249-255,I0013,I0014,I0047,共7页
The interaction of reactants with catalysts has always been an important subject for catalytic reactions.As a promising catalyst with versatile applications,titania has been intensively studied for decades.In this wor... The interaction of reactants with catalysts has always been an important subject for catalytic reactions.As a promising catalyst with versatile applications,titania has been intensively studied for decades.In this work we have investigated the role of bridge bonded oxygen vacancy(Ov)in methyl groups and carbon monoxide(CO)adsorption on rutile TiO2(110)(R-TiO2(110))with the temperature programmed desorption technique.The results show a clear different tendency of the desorption of methyl groups adsorbed on bridge bonded oxygen(Ob),and CO molecules on the five coordinate Ti4+sites(Ti5c)as the Ovconcentration changes,suggesting that the surface defects may have crucial influence on the absorption of species on different sites of R-TiO2(110). 展开更多
关键词 Temperature programmed desorption TiO2(110) Bridge bonded oxygen vacancy Adsorption sites Surface defects
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Microstructure and wear performance of Al5083/CeO_2/SiC mono and hybrid surface composites fabricated by friction stir processing 认领 引用
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作者 M.AMRA Khalil RANJBAR S.A.HOSSEINI 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第5期866-878,共13页
Friction stir processing（FSP） was utilized to produce surface composites by incorporating nano-sized cerium oxide（CeO2） and silicon carbide（SiC） particles individually and in combined form into the Al5083 alloy ... Friction stir processing（FSP） was utilized to produce surface composites by incorporating nano-sized cerium oxide（CeO2） and silicon carbide（SiC） particles individually and in combined form into the Al5083 alloy matrix. The study signified the role of these reinforcements on microstructure and wear behavior of the resultant surface composite layers. The wear characteristics of the resultant mono and hybrid surface composite layers were investigated using a pin-on-disc wear tester at room temperature. The microstructural observations of FSPed regions and the worn out surfaces were performed by optical and scanning electron microscopy. Considerable grain refinement and uniform distribution of reinforcement particles were achieved inside the nugget zone. All the composite samples showed higher hardness and wear resistance compared to the base metal. Among the composite samples, the hybrid composite（Al5083/CeO2/SiC） revealed the highest wear resistance and the lowest friction coefficient, whereas the Al5083/SiC composite exhibited the highest hardness, i.e., 1.5 times as hard as that of the Al5083 base metal. The enhancement in wear behavior of the hybrid composites was attributed to the solid lubrication effect provided by CeO2 particles. The predominant wear mechanism was identified as severe adhesive in non-composite samples, which changed to abrasive wear and delamination in the presence of reinforcing particles. 展开更多
关键词 A15083 alloy friction stir processing CeO2 SiC surface composites wear mechanism
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The Ab Initio Studies of NO Chemisorption on TiO_2(110) Surface 认领 引用
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作者 吴立明 章永凡 《Chinese Journal of Structural Chemistry》 SCIE CAS 1999年第4期304-309,共6页
The studies of NO chemisorption on TiO2(110) surface are the base of research to NO decomposed to N2O on TiO2 surface. In this paper, 12 kinds of possible models of NO adsorbed on TiO2 perfect and defect surface were ... The studies of NO chemisorption on TiO2(110) surface are the base of research to NO decomposed to N2O on TiO2 surface. In this paper, 12 kinds of possible models of NO adsorbed on TiO2 perfect and defect surface were calculated by use of ab initio cluster method. We carried out optimization of the geometry, calculation of the chemisorption energy and analysis of the Mulliken population to those adsorption models. According to the calculation results, it can be got that the adsorbed decomposition of NO on defect surface is more advantageous and M6 and M12 are the important models to NO chemisorption and decomposition on TiO2 surface. 展开更多
关键词 TiO2 (110) surface NO chemisorption quantum chemistry
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CeO_2(110)表面上CO氧化反应的密度泛函理论研究 认领 引用 被引量：4
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作者 滕波涛 蒋仕宇 +2 位作者 郭晓伟 袁金焕 罗孟飞 《化学学报》 SCIE CAS 北大核心 2009年第24期2765-2772,共8页
利用密度泛函理论系统研究了O2与CO在CeO2(110)表面的吸附反应行为.研究表明,O2在清洁的CeO2(110)表面吸附热力学不利,而在氧空位表面为强化学吸附,O2分子被活化,可能是重要的氧化反应物种.CO在清洁的CeO2(110)表面有化学吸附与物理吸... 利用密度泛函理论系统研究了O2与CO在CeO2(110)表面的吸附反应行为.研究表明,O2在清洁的CeO2(110)表面吸附热力学不利,而在氧空位表面为强化学吸附,O2分子被活化,可能是重要的氧化反应物种.CO在清洁的CeO2(110)表面有化学吸附与物理吸附两种构型,前者形成二齿碳酸盐物种,后者与表面仅存在弱相互作用.在氧空位表面,CO可分子吸附或形成碳酸盐物种,相应吸附能均较低.当表面氧空位吸附O2后(O2/Ov),CO可吸附生成碳酸盐或直接生成CO2,与原位红外光谱结果相一致.过渡态计算发现,O2/Ov/CeO2(110)表面的三齿碳酸盐物种经两齿、单齿过渡态脱附生成CO2.利用扩展休克尔分子轨道理论分析了典型吸附构型的电子结构,说明表面碳酸盐物种三个氧原子电子存在离域作用,物理吸附的CO及生成的CO2电子结构与相应自由分子相似. 展开更多
关键词 CO氧化 CeO2(110)表面 密度泛函理论 扩展休克尔分子轨道理论
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甲醛在CeO_2(110)表面的吸附 认领 引用
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作者 姚小丹 韩姣囡 +3 位作者 金丽芳 刘晓娜 蒋仕宇 滕波涛 《广州化工》 CAS 2016年第5期134-137,共4页
利用密度泛函理论计算了甲醛在洁净CeO_2(110)表面的吸附行为,发现甲醛在表面存在化学与物理吸附。甲醛化学吸附时,甲醛的碳、氧原子分别与表面氧、铈原子发生作用,生成CH_2O_2,平面结构变为四面体构型;吸附能随覆盖度的减小而增大;电... 利用密度泛函理论计算了甲醛在洁净CeO_2(110)表面的吸附行为,发现甲醛在表面存在化学与物理吸附。甲醛化学吸附时,甲醛的碳、氧原子分别与表面氧、铈原子发生作用,生成CH_2O_2,平面结构变为四面体构型;吸附能随覆盖度的减小而增大;电子结构分析表明,其最高占据轨道nO的电子进入表面铈原子的空轨道,形成Ce-Os化学键;而表面氧原子的电子填充到甲醛的C-Of反键轨道,形成新的C-Os键,甲醛的C-Of键长伸长。而物理吸附的甲醛,平面结构不变,吸附能较小,电子结构无明显变化。 展开更多
关键词 密度泛函理论 CeO2(110) 吸附能 态密度
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Enhanced low-temperature NH3-SCR performance of CeTiOx catalyst via surface Mo modification 认领 引用 被引量：13
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作者 Lulu Li Peixiao Li +4 位作者 Wei Tan Kaili Ma Weixin Zou Changjin Tang Lin Dong 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第2期364-373,共10页
The effect of molybdenum oxide on the activity and durability of Ce O2-Ti O2 catalyst for NO reduction by NH3 was examined. It was found that the introduction of Mo could improve the low-temperature NH3-SCR activity a... The effect of molybdenum oxide on the activity and durability of Ce O2-Ti O2 catalyst for NO reduction by NH3 was examined. It was found that the introduction of Mo could improve the low-temperature NH3-SCR activity and SO2/H2 O durability of the Ce O2-Ti O2 catalyst and an optimal loading of Mo was 4?wt.%. The best Mo O3/Ce O2-Ti O2 catalyst displayed over 90% NO conversion from 200 °C to 400 °C and obtained 4-fold increase in NO conversion compared to Ce O2-Ti O2 at 150 °C. The characterization results revealed that the number of Br?nsted acid sites over Mo O3/Ce O2-Ti O2 was significantly increased, and the adsorption of nitrate species was dramatically weakened because of the coverage of Mo O3, which were favorable for the high NH3-SCR performance. It is believed that the Mo O3/Ce O2-Ti O2 catalyst is a suitable substitute for the NH3-SCR reaction. 展开更多
关键词 DeNOx CeO2-TiO2 catalyst MoO3 modification SO2 poisoning Surface acidity
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Influence of preparation methods on the physicochemical properties and catalytic performance of MnO_x-CeO_2 catalysts for NH_3-SCR at low temperature 认领 引用 被引量：59
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作者 Xiaojiang Yao Kaili Ma +4 位作者 Weixin Zou Shenggui He Jibin An Fumo Yang Lin Dong 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2017年第1期146-159,共14页
This work examines the influence of preparation methods on the physicochemical properties and catalytic performance of MnOx‐CeO2 catalysts for selective catalytic reduction of NO by NH3 (NH3‐SCR) at low temperature.... This work examines the influence of preparation methods on the physicochemical properties and catalytic performance of MnOx‐CeO2 catalysts for selective catalytic reduction of NO by NH3 (NH3‐SCR) at low temperature. Five different methods, namely, mechanical mixing, impregnation,hydrothermal treatment, co‐precipitation, and a sol‐gel technique, were used to synthesizeMnOx‐CeO2 catalysts. The catalysts were characterized in detail, and an NH3‐SCR model reaction waschosen to evaluate the catalytic performance. The results showed that the preparation methodsaffected the catalytic performance in the order: hydrothermal treatment > sol‐gel > co‐precipitation> impregnation > mechanical mixing. This order correlated with the surface Ce3+ and Mn4+ content,oxygen vacancies and surface adsorbed oxygen species concentration, and the amount of acidic sitesand acidic strength. This trend is related to redox interactions between MnOx and CeO2. The catalystformed by a hydrothermal treatment exhibited excellent physicochemical properties, optimal catalyticperformance, and good H2O resistance in NH3‐SCR reaction. This was attributed to incorporationof Mnn+ into the CeO2 lattice to form a uniform ceria‐based solid solution (containing Mn‐O‐Cestructures). Strengthening of the electronic interactions between MnOx and CeO2, driven by thehigh‐temperature and high‐pressure conditions during the hydrothermal treatment also improved the catalyst characteristics. Thus, the hydrothermal treatment method is an efficient and environment‐friendly route to synthesizing low‐temperature denitrification (deNOx) catalysts. 展开更多
关键词 MnOx‐CeO2 catalyst Preparation method Nitrogen oxides Low‐temperature NH3‐SCR Electron interaction Surface acidity
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Introduction manner of sulfate acid for improving the performance of SO_42–/CeO_2 on selective catalytic reduction of NO by NH_3 认领 引用 被引量：12
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作者 宋忠贤 张秋林 +3 位作者 宁平 刘昕 樊洁 黄真真 《Journal of Rare Earths》 SCIE EI CAS CSCD 2016年第7期667-674,共8页
A series of sulfated CeO2 catalysts were synthesized by impregnation and sol-gel methods and used for selective catalytic reduction （SCR） of NOx by NH3. The results showed that the sulfated CeO2 catalysts prepared b... A series of sulfated CeO2 catalysts were synthesized by impregnation and sol-gel methods and used for selective catalytic reduction （SCR） of NOx by NH3. The results showed that the sulfated CeO2 catalysts prepared by sol-gel method showed excellent catalytic activity at 150-50 ℃, and more than 90% NOx conversion was obtained at 232-450 ℃ with a gas hourly space velocity of 60000 h-1. The catalysts were characterized by X-ray diffraction （XRD）, N2 adsorption, Raman, thermogravimetry （TG）, H2-tem- perature-programmed reduction （H2-TPR） and Py-infrared spectroscopy （Py-IR）. The excellent SCR performance was associated with the surface acidity and the micro-structure. The introduction of sulfate acid into CeO2 could increase the amount of BrOnsted and Lewis acid sites over the catalysts, resulting in the improvement of the low temperature activity. The sulfated CeO2 catalysts prepared by sol-gel method possessed lower crystallization degree, excellent redox property and larger specific surface areas, which were responsible for the superior SCR performance. 展开更多
关键词 sulfated CeO2 selective catalytic reduction surface acidity micro-structure rare earthsO
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Doping effect of cations(Zr4+,Al3+,and Si4+) on MnO_x/CeO_2 nano-rod catalyst for NH_3-SCR reaction at low temperature 认领 引用 被引量：7
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作者 Xiaojiang Yao Jun Cao +4 位作者 Li Chen Keke Kang Yang Chen Mi Tian Fumo Yang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第5期733-743,共11页
Thermally stable Zr4+, Al3+, and Si4+ cations were incorporated into the lattice of CeO2 nano‐rods (i.e., CeO2‐NR) in order to improve the specific surface area. The undoped and Zr4+, Al3+, and Si4+ doped nano‐rods... Thermally stable Zr4+, Al3+, and Si4+ cations were incorporated into the lattice of CeO2 nano‐rods (i.e., CeO2‐NR) in order to improve the specific surface area. The undoped and Zr4+, Al3+, and Si4+ doped nano‐rods were used as supports to prepare MnOx/CeO2‐NR, MnOx/CZ‐NR, MnOx/CA‐NR, and MnOx/CS‐NR catalysts, respectively. The prepared supports and catalysts were comprehensively characterized by transmission electron microscopy (TEM), high‐resolution TEM, X‐ray diffraction, Raman and N2‐physisorption analyses, hydrogen temperature‐programmed reduction, ammonia temperature‐programmed desorption, in situ diffuse reflectance infrared Fourier‐transform spectroscopic analysis of the NH3 adsorption, and X‐ray photoelectron spectroscopy. Moreover, the catalytic performance and H2O+SO2 tolerance of these samples were evaluated through NH3‐selective catalytic reduction (NH3‐SCR) in the absence or presence of H2O and SO2. The obtained results show that the MnOx/CS‐NR catalyst exhibits the highest NOx conversion and the lowest N2O concentration, which result from the largest number of oxygen vacancies and acid sites, the highest Mn4+ content, and the lowest redox ability. The MnOx/CS‐NR catalyst also presents excellent resistance to H2O and SO2. All of these phenomena suggest that Si4+ is the optimal dopant for the MnOx/CeO2‐NR catalyst. 展开更多
关键词 MnOx/CeO2 nano‐rod catalyst Doping effect Oxygen vacancy Surface acidity Low‐temperature NH3‐SCR reaction
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CeO_2用于柴油机尾气NO还原的DFT研究 认领 引用 被引量：1
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作者 黄河 孙平 +1 位作者 叶松 刘军恒 《中国稀土学报》 CAS CSCD 北大核心 2016年第5期618-624,共7页
采用密度泛函理论广义梯度近似的RPBE方法结合周期性平板模型研究了NO分子分别以N端和O端两种吸附形式在洁净的以及具有氧空穴的CeO_2(110)表面的吸附行为。对比了不同的吸附位及不同覆盖度下的几何构型参数与吸附能。研究结果表明:CeO_... 采用密度泛函理论广义梯度近似的RPBE方法结合周期性平板模型研究了NO分子分别以N端和O端两种吸附形式在洁净的以及具有氧空穴的CeO_2(110)表面的吸附行为。对比了不同的吸附位及不同覆盖度下的几何构型参数与吸附能。研究结果表明:CeO_2(110)表面O原子上的吸附构型为较稳定的吸附构型,且N端吸附较O端有利;NO在洁净CeO_2(110)表面为物理吸附;当CeO_2(110)表面存在氧空穴时,吸附能明显增大且均大于40 k J·mol-1,为化学吸附;覆盖度为0.25 m L时的吸附比较稳定。计算了NO分子吸附前后的态密度以及电荷密度,研究发现:NO分子与底物之间具有相互作用,且整个吸附体系发生了电荷从Ce原子向NO分子的转移,O端吸附时转移的电荷较N端的多。 展开更多
关键词 催化剂 密度泛函理论 吸附 NO CeO2(110)表面
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Thickness modulation effect of CeO_2 layer for YBCO films grown by pulsed laser deposition 认领 引用 被引量：4
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作者 Xiang Wu Lin-Fei Liu +3 位作者 Yan-Jie Yao Meng-Lin Wang Bin-Bin Wang Yi-Jie Li 《Rare Metals》 SCIE EI CAS CSCD 2018年第3期225-231,共7页
CeO2 film plays an essential role in nucleation and growth of YBa2 Cu3 O（7-x）（YBCO） films. In this work,the dependence of superconducting properties of YBCO on CeO2 films with different thicknesses was investigate... CeO2 film plays an essential role in nucleation and growth of YBa2 Cu3 O（7-x）（YBCO） films. In this work,the dependence of superconducting properties of YBCO on CeO2 films with different thicknesses was investigated,in order to achieve fabrication of high-performance YBCO coated conductors in industrial scale. The crystalline structure and morphology of CeO2 films with thickness ranging from 21 to 563 nm were systematically characterized by means of X-ray diffraction（XRD）, atomic force microscope（AFM） and reflection high-energy electron diffraction（RHEED）. Additional focus was addressed on evolution of the surface quality of CeO2 films with thickness increasing. The results show that at the optimal thickness of 221 nm, CeO2 film exhibits sharp in-plane and out-of-plane texture with full width of half maximum（FWHM） values of 5.9° and 1.8°, respectively, and smooth surface with a mean root-mean-square（RMS） roughness value as low as 0.6 nm. Combing RHEED and transmission electron microscope（TEM） cross-sectional analysis, it is found that nucleation and growth of CeO2 films at early stage remain in island growth mode with rougher surface,while further increasing the thickness beyond the optimal thickness leads to weak surface quality, consequently resulting in degradation of superconductor layers deposited subsequently. Eventually, a critical current density（Jc） as high as 4.6×10-6 A·cm-（-2）（77 K, self-field） is achieved on a YBCO film on a thickness-modulated CeO2/MgO/Y2 O3/Al2 O3/C276 architecture, demonstrating the advantages of CeO2 films as buffer layer in high-throughput manufacture of coated conductors. 展开更多
关键词 CeO2 films Thickness modulation Pulsed laser deposition Surface quality
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Characterization and catalytic performance of CeO_2-Co/SiO_2 catalyst for Fischer-Tropsch synthesis using nitrogen-diluted synthesis gas over a laboratory scale fixed-bed reactor 认领 引用 被引量：2
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作者 Xiaoping Dai Changchun Yu 《Journal of Natural Gas Chemistry》 2008年第1期17-23,共7页
The surface species of CO hydrogenation on CeO2-Co/SiO2 catalyst were investigated using the techniques of temperature programmed reaction and transient response method. The results indicated that the formation of H2O... The surface species of CO hydrogenation on CeO2-Co/SiO2 catalyst were investigated using the techniques of temperature programmed reaction and transient response method. The results indicated that the formation of H2O and CO2 was the competitive reaction for the surface oxygen species, CH4 was produced via the hydrogenation of carbon species step by step, and C2 products were formed by the polymerization of surface-active carbon species （-CH2-）. Hydrogen assisted the dissociation of CO. The hydrogenation of surface carbon species was the rate-limiting step in the hydrogenation of CO over CeO2-Co/SiO2 catalyst. The investigation of total pressure, gas hourly space velocity （GHSV）, and product distribution using nitrogen-rich synthesis gas as feedstock over a laboratory scale fixed-bed reactor indicated that total pressure and GHSV had a significant effect on the catalytic performance of CeO2-Co/SiO2 catalyst. The removal of heat and control of the reaction temperature were extremely critical steps, which required lower GHSV and appropriate CO conversion to avoid the deactivation of the catalyst. The feedstock of nitrogen-rich synthesis gas was favorable to increase the conversion of CO, but there was a shift of product distribution toward the light hydrocarbon. The nitrogen-rich synthesis gas was feasible for F-T synthesis for the utilization of remote natural gas. 展开更多
关键词 CeO2-Co/SiO2 catalyst Fischer-Tropsch synthesis surface species reaction condition nitrogen-rich synthesis gas product distribution
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Surface state of molybdenum cations in MoO_3/CeO_2 认领 引用 被引量：2
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作者 DONG Lin, HU Jingqiu, XU Bin and CHEN YiDepartment of Chemistry, Institute of Mesoscopic Solid State Chemistry, Nanjing University, Nanjing 210093, China 《Chinese Science Bulletin》 1997年第15期1278-1282,共5页
STUDY on the surface interaction of supported catalysts is a fundamental subject in catalysis fortheir wide application in industrial reactions. In the past decades, deep investigation on the in-teraction between the ... STUDY on the surface interaction of supported catalysts is a fundamental subject in catalysis fortheir wide application in industrial reactions. In the past decades, deep investigation on the in-teraction between the active species and the supports, such as γ-Al2O3, SiO2, TiO2, ZrO2,etc., has been carried out, and the properties of the supports as well as the roles of the sup-ported acitve species at different states in the catalysis process have been further clarified.Recently, some novel catalysts, with rare-earth metal oxides as supports, have attracted muchattention for their unique properties in the catalysis application, such as the reaction of CO+H2 and the automobile exhaust emission control. 展开更多
关键词 MoO3 CeO2 dispersion capacity incorporation model surface species.
Unique adsorption behaviors of NO and O_2 at hydrogenated anatase TiO_2(101) 认领 引用 被引量：1
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作者 Fei Li Wen-Hao Huang Xue-Qing Gong 《Chinese Chemical Letters》 SCIE CAS CSCD 2018年第6期765-768,共4页
Titanium dioxide（TiO2） is one of the most widely studied transition metal oxides, especially for its unique performances in heterogeneous photocatalysis. Different phases of TiO2 have been found to exhibit different... Titanium dioxide（TiO2） is one of the most widely studied transition metal oxides, especially for its unique performances in heterogeneous photocatalysis. Different phases of TiO2 have been found to exhibit different photo-activities, though the origins are still not fully understood. In this work, we use the density functional theory（DFT） calculations, corrected by on-site Coulomb and long-range dispersion interactions, to study the adsorptions of nitric oxide（NO） and oxygen（O2） molecules on the clean and hydrogenated anatase TiO2（101） surfaces. We also compare the detailed calculated results regarding their structural, energetic and electronic properties with those obtained at rutile TiO2（110）. It has been found that the behaviors of the surface localized electrons being transferred from adsorbed H, as well as the adsorption behaviors of NO and O2 are quite different at the two surfaces, which can be attributed to their characteristic local bonding structures around the surface hydroxyl. These results may also help explain the different photocatalytic activities of these two main facets of anatase and rutile TiO2 展开更多
关键词 Anatase TiO2（101） Rutile TiO2（110） Surface adsorptions Surface hydroxyls Localized electrons Photocatalysis Density functional theory
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