The slurry-bed hydrocracking of Karamay VGO with water-soluble dispersed catalyst was studied and the catalyst after being separated from the reaction products was analyzed by using LRS,XRD and XPS to identify the cry...The slurry-bed hydrocracking of Karamay VGO with water-soluble dispersed catalyst was studied and the catalyst after being separated from the reaction products was analyzed by using LRS,XRD and XPS to identify the crystal structure of the catalyst.In this paper,the catalytic functions of molybdenum,nickel and iron were studied respectively during the slurry-phase hydrocracking while using diphenylmethane as the model compound and VGO from Karamay crude as the feedstock.The test results showed that,during the slurry-phase hydrocracking of heavy oil,the metal sulfides entered into chemical reactions with the free-radical intermediate H·formed on the catalyst surface.The free-radical intermediate H·formed on the catalyst surface could react with the free-radicals of big molecules and could suppress coke deposition.展开更多
Shot cokes are frequently formed in the delayed coking unit treating the super viscous oil at PetroChina＇s Liaohe Petrochemical Company. Considerable work has been carded out to avoid the formation of shot cokes. The...Shot cokes are frequently formed in the delayed coking unit treating the super viscous oil at PetroChina＇s Liaohe Petrochemical Company. Considerable work has been carded out to avoid the formation of shot cokes. The test results obtained have shown that the property of super viscous oil has played a key role in the formation of shot cokes. After adjusting and optimizing the process indices the operating regime of the delayed coking unit at a throughput of 118t/h of the super viscous oil is specified as follows： a reaction temperature of 498-502℃, a reaction pressure of 0.17-0.25 MPa, a recycle ratio of 0.5-0.6 and a fractionation tower bottom temperature of 355-365 ℃. In the meantime, the delayed coking process has adopted measures to enhance pre-fractionation of the feedstock to rationally remove light fractions and maintain a steady gas velocity in order to avoid the formation of shot cokes.展开更多
A series of noble metal catalysts （Ru, Rh, Ir, Pt, and Pd） supported on alumina-stabilized magnesia （Spinel） were used to produce syngas by methane reforming with carbon dioxide. The synthesized catalysts were cha...A series of noble metal catalysts （Ru, Rh, Ir, Pt, and Pd） supported on alumina-stabilized magnesia （Spinel） were used to produce syngas by methane reforming with carbon dioxide. The synthesized catalysts were characterized using BET, TPR, TPO, TPH, and H2S chemisorption techniques. The activity results showed high activity and stability for the Ru and Rh catalysts. The TPO and TPH analyses indicated that the main reason for lower activity and stability of the Pd catalyst was the formation of the less reactive deposited carbon and sintering of the catalyst.展开更多
Fe-Al catalysts with hollow nano-spherical structures were synthesized following the hard template method using self-made carbon spheres as templates.The catalytic performance of these catalysts in the production of c...Fe-Al catalysts with hollow nano-spherical structures were synthesized following the hard template method using self-made carbon spheres as templates.The catalytic performance of these catalysts in the production of carbon nanotubes(CNTs)was evaluated through ethane catalytic cracking on a fixed bed reactor.Furthermore,the influence of these hollow nanospheres on the yield and quality of CNTs was investigated.The results showed that compared to the irregular-shaped catalyst synthesized by coprecipitation and the catalyst with micro-spherical structures prepared by the impregnation method,the Fe-Al hollow nano-spherical catalysts exhibited significantly enhanced specific surface area and pore volume,reaching 236 m^(2)/g and 0.77 cm^(3)/g,respectively.At a reaction temperature of 700℃ and an ethane feed rate of 90 mL/min,the CNTs yield of Fe-Al hollow nano-spherical catalyst reached as high as 48.6 gCNT/gcat,which was 1.8 and 4.6 times higher than the yield of irregular-shaped(27.7 gCNT/gcat)and micro-spherical(10.5 gCNT/gcat)catalysts,respectively.This was mainly attributed to the hollow cavity structure of Fe-Al catalyst providing sufficient space for the CNTs growth.As a result,the blockage of catalyst internal pores was prevented by the formed CNTs,which isolated ethane molecules from the active sites and lead to catalyst deactivation.Furthermore,the CNTs synthesized by Fe-Al hollow nano-spherical catalyst exhibited a uniform diameter distribution and a higher degree of graphitization.展开更多
The effects of carbon dioxide content on the catalytic performance and coke formation of nickel catalyst supported on mesoporous nanocrystalline zirconia with high surface area and pure tetragonal crystalline phase we...The effects of carbon dioxide content on the catalytic performance and coke formation of nickel catalyst supported on mesoporous nanocrystalline zirconia with high surface area and pure tetragonal crystalline phase were investigated in methane reforming with carbon dioxide. The samples were characterized by XRD, BET, TPR, TPO, TPH, TEM, and SEM techniques. The catalyst prepared showed high surface area and a mesoporous structure with a narrow pore size distribution. The obtained results revealed that the increase in CO2 content increased the methane conversion and stability of the catalyst and significantly reduced the coke deposition. The TPH analysis showed that several species of carbon with different reactivities toward hydrogenation were deposited on the spent catalysts employed under different CO2 contents.展开更多
Cu/ZrO2 catalysts for methanol synthesis from CO2/H2 were respectively prepared by deposition coprecipitation （DP） and solid state reaction （SR） methods. There is an intimate interaction between copper and zirconi...Cu/ZrO2 catalysts for methanol synthesis from CO2/H2 were respectively prepared by deposition coprecipitation （DP） and solid state reaction （SR） methods. There is an intimate interaction between copper and zirconia, which strongly affects the reduction property and catalytic performance of the catalysts. The stronger the interaction, the lower the reduction temperature and the better the performance of the catalysts. Surface area, pore structure and crystal structure of the catalysts are mainly controlled by preparation methods and alkalinity of synthesis system. The conversion of CO2 and selectivity of methanol are higher for DP catalysts than for SP catalysts.展开更多
The introduction of mesoporous nanosize zirconia to the catalyst for methanol synthesis dedicates the nanosized catalyst and mesoporous duplicated properties. The catalyst bears the larger surface area, larger mesopor...The introduction of mesoporous nanosize zirconia to the catalyst for methanol synthesis dedicates the nanosized catalyst and mesoporous duplicated properties. The catalyst bears the larger surface area, larger mesoporous volume and more uniform diameter, more surface metal atoms and oxygen vacancies than the catalyst prepared with the conventional coprecipitation method. The modification of microstructure and electronic effect could result in the change of the reduced chemical state and decrease of reducuction temperature of copper, donating the higher activity and methanol selectivity to the catalyst. The results of methanol synthesis demonstrate that the Cu^＋ is the optimum active site. Also, the interaction between the copper and zirconia shows the synergistic effect to fulfil the methanol synthesis.展开更多
Colorimetry often suffers from deficiency in quantitative determination,susceptibility to ambient illuminance,and low sensitivity and visual resolution to tiny color changes.To offset these deficiencies,we incorporate...Colorimetry often suffers from deficiency in quantitative determination,susceptibility to ambient illuminance,and low sensitivity and visual resolution to tiny color changes.To offset these deficiencies,we incorporate deep machine learning into colorimetry by introducing a convolutional neural network(CNN)with powerful parallel processing,self-organization,and self-learning capabilities.As a proof of concept,a plasmonic nanosensor is proposed for the colorimetric detection of glucose by coupling Benedict’s reagent with gold nanoparticles(AuNPs),which relies on the assemble of AuNPs into dendritic nanochains by Cu2O.The distinct difference of refractive index between Cu2O and Au and the localized surface plasmon resonance coupling effect among AuNPs leads to a broad spectral shift as well as abundant color changes,thereby providing sufficient data for selflearning enabled by machine learning.The CNN is then used to fully diversify the learning and training of the images from standard samples under different ambient conditions and to obtain a classifier that can not only recognize tiny color changes that are imperceptible to human eyes,but also exhibit high accuracy and excellent anti-environmental interference capability.This classifier is then compiled as an application(APP)and implanted into a smartphone with Android environment.306 clinical urine samples were detected using the proposed method and the results showed a satisfactory correlation(87.6%)with that of a standard blood glucose test method.More importantly,this method can be generalized to other applications in colorimetry,and more broadly,in other scientific domains that involve image analysis and quantification.展开更多
The careful design of nano-architectures and smart hybridization of expected active materials can lead to more advanced properties. Here we have engineered a novel hierarchical branching Cu/Cu2O/CuO heteronanostructur...The careful design of nano-architectures and smart hybridization of expected active materials can lead to more advanced properties. Here we have engineered a novel hierarchical branching Cu/Cu2O/CuO heteronanostructure by combining a facile hydrothermal method and subsequent controlled oxidation process. The fine structure and epitaxial relationship between the branches and backbone are investigated by high-resolution transmission electron microscopy. Moreover, the evolution of the branch growth has also been observed during the gradual oxidation of the Cu nanowire surface. The experimental results suggest that the surface oxidation needs to be performed via a two-step exposure process to varying humidity in order to achieve optimized formation of a core-shell structured branching architecture. Finally, a proof-of-concept of the function of such a hierarchical framework as the anode material in lithium-ion batteries is demonstrated. The branching core-shell heterostructure improves battery performance by several means： （i） The epitaxially grown branches provide a high surface area for enhanced electrolyte accessibility and high resistance to volume change induced by Li^＋ intercalation/extraction; （ii） the core-shell structure with its well-defined heterojunction increases the contact area which facilitates effective charge transport during lithiation; （iii） the copper core acts as a current collector as well as providing structural reinforcement.展开更多
Porous niobium oxide nanowires synthesized via a solvothermal method exhibited decreased bandgap,en- hanced light absorption and reduced charge-recombination rate.The porous Nb2O5 nanowires showed increased performanc...Porous niobium oxide nanowires synthesized via a solvothermal method exhibited decreased bandgap,en- hanced light absorption and reduced charge-recombination rate.The porous Nb2O5 nanowires showed increased performance for the photocatalytic H2 evolution and photo- degradation of rhodamine B,as compared to their solid counterparts,which could be ascribed to the peculiar porous nanostructure.展开更多
Based on a general classification and characteristic comparison of the existing models, a new model for non-catalytic gas-solid reactions is proposed and a general formulation for the model in terms of the solid conve...Based on a general classification and characteristic comparison of the existing models, a new model for non-catalytic gas-solid reactions is proposed and a general formulation for the model in terms of the solid conversion, X, is presented in mis paper. The model, referred to the generalized model, is demonstrated to be applicable to any solid reactant of general structure ranging from highly porous to nonporous materials. It is shown that the generalized model incorporates the grain and pore structure for a solid pellet and can be reduced to the grain and random pore models as extreme cases.展开更多
Copper nanorods have been synthe-sized in mesoporous SBA-15 by a low-temperature metal organic chemical vapor deposition (MOCVD) employing copper (II) acetylacetonate, Cu(acac)2, and hydrogen as a precursor and reacta...Copper nanorods have been synthe-sized in mesoporous SBA-15 by a low-temperature metal organic chemical vapor deposition (MOCVD) employing copper (II) acetylacetonate, Cu(acac)2, and hydrogen as a precursor and reactant gas, re- spectively. The hydrogen plays an important role in chemical reduction of oganometallic precursor which enhances mass transfer in the interior of the SBA-15 porous substrate. Such copper nanostructures are of great potentials in the semiconductor due to their unusual optical, magnetic and electronic properties. In addition, it has been found that chemically modi- fying the substrate surface by carbon deposition is crucial to such synthesis of copper nanostructures in the interior of the SBA-15, which is able to change the surface properties of SBA-15 from hydrophilic to hydrophobic to promote the adsorption of organic cupric precursor. It has also been found that the copper nanoparticles deposited on the external sur- face are almost eliminated and the copper nanorods are more distinct while the product was treated with ammonia. This approach could be achieved under a mild condition: a low temperature (400℃) and vac-uum (2 kPa) which is extremely milder than the con- ventional method. It actually sounds as a foundation which is the first time to synthesize a copper nanorod at a mild condition of a low reaction temperature and pressure.展开更多
The ordered carbon nanorods (OCNR) was successfully synthesized using the mesoporous silica as hard template. XRD tests and TEM observations showed that OCNR was composed of arrayed carbon nanorods in the p6mm symmetr...The ordered carbon nanorods (OCNR) was successfully synthesized using the mesoporous silica as hard template. XRD tests and TEM observations showed that OCNR was composed of arrayed carbon nanorods in the p6mm symmetry. N2 sorption analysis demonstrated that OCNR possessed the typically mesoporous structure and centralized mesopore distribution. Compared with Maxsorb, an active carbon with super high surface area, OCNR has superior capacitive behavior, power output and high fre- quency performance due to its ordered pore-structure, which favors the fast diffusion of hydrated ions. As evidenced by cyclic voltammetry measurements, OCNR shows superior capacitive behaviors (exhibiting a high capacitance of 166 F/g even at very high sweep rate of 50 mV/s, as compared to much reduced capacitance of 73 F/g for Maxsorb at the same sweep rate). OCNR can provide much higher power density while still maintaining good energy density, which offers a great potential in electrochemical double layer ca- pacitor (EDLC), particularly for applications where both high power output and energy density are required.展开更多
Carbon nanotubes (CNTs)/mesostructured silica core-shell nanowires with a carbon nanotube core and controllable highly ordered periodic mesoporous silica shell are syntheiszed via the interfacial surfac- tant template...Carbon nanotubes (CNTs)/mesostructured silica core-shell nanowires with a carbon nanotube core and controllable highly ordered periodic mesoporous silica shell are syntheiszed via the interfacial surfac- tant template. The core-shell nanowires are characterized by transmission electron microscope (TEM), X-ray diffraction pattern (XRD) and nitrogen sorption/desorption. The results indicate that the core-shell nanowires have highly ordered periodic mesoporous silica shell (space group p6mm), high BET sur- face area and narrow pore size distribution. Moreover, the morphology of core-shell nanowires can be controlled by the pH value. The core-shell nanowires have promising applications in biosensors, nanoprobes and energy storage due to their good dispersibility in polar solvents.展开更多
Tree-like SnO_(2) nanodendrites in large amounts have been prepared through two-step reactions.The nanoparticles used as the precursors have taken aggrega-tion forming tree-like or string of nanodendrtie.The samples w...Tree-like SnO_(2) nanodendrites in large amounts have been prepared through two-step reactions.The nanoparticles used as the precursors have taken aggrega-tion forming tree-like or string of nanodendrtie.The samples were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),high-resolution transmission electron microscopy(HRTEM)and energy dispersive spectrometer(EDS),respectively.The results showed that molar ratio of the ethanol/distilled water is an important factor for formation of the different dendrite structures.There are different morphologies between tree-like SnO_(2) nanowhiskers and bunch of SnO_(2) nanorods.However,they are growing along the [112].展开更多
文摘The slurry-bed hydrocracking of Karamay VGO with water-soluble dispersed catalyst was studied and the catalyst after being separated from the reaction products was analyzed by using LRS,XRD and XPS to identify the crystal structure of the catalyst.In this paper,the catalytic functions of molybdenum,nickel and iron were studied respectively during the slurry-phase hydrocracking while using diphenylmethane as the model compound and VGO from Karamay crude as the feedstock.The test results showed that,during the slurry-phase hydrocracking of heavy oil,the metal sulfides entered into chemical reactions with the free-radical intermediate H·formed on the catalyst surface.The free-radical intermediate H·formed on the catalyst surface could react with the free-radicals of big molecules and could suppress coke deposition.
文摘Shot cokes are frequently formed in the delayed coking unit treating the super viscous oil at PetroChina＇s Liaohe Petrochemical Company. Considerable work has been carded out to avoid the formation of shot cokes. The test results obtained have shown that the property of super viscous oil has played a key role in the formation of shot cokes. After adjusting and optimizing the process indices the operating regime of the delayed coking unit at a throughput of 118t/h of the super viscous oil is specified as follows： a reaction temperature of 498-502℃, a reaction pressure of 0.17-0.25 MPa, a recycle ratio of 0.5-0.6 and a fractionation tower bottom temperature of 355-365 ℃. In the meantime, the delayed coking process has adopted measures to enhance pre-fractionation of the feedstock to rationally remove light fractions and maintain a steady gas velocity in order to avoid the formation of shot cokes.
文摘A series of noble metal catalysts （Ru, Rh, Ir, Pt, and Pd） supported on alumina-stabilized magnesia （Spinel） were used to produce syngas by methane reforming with carbon dioxide. The synthesized catalysts were characterized using BET, TPR, TPO, TPH, and H2S chemisorption techniques. The activity results showed high activity and stability for the Ru and Rh catalysts. The TPO and TPH analyses indicated that the main reason for lower activity and stability of the Pd catalyst was the formation of the less reactive deposited carbon and sintering of the catalyst.
文摘Fe-Al catalysts with hollow nano-spherical structures were synthesized following the hard template method using self-made carbon spheres as templates.The catalytic performance of these catalysts in the production of carbon nanotubes(CNTs)was evaluated through ethane catalytic cracking on a fixed bed reactor.Furthermore,the influence of these hollow nanospheres on the yield and quality of CNTs was investigated.The results showed that compared to the irregular-shaped catalyst synthesized by coprecipitation and the catalyst with micro-spherical structures prepared by the impregnation method,the Fe-Al hollow nano-spherical catalysts exhibited significantly enhanced specific surface area and pore volume,reaching 236 m^(2)/g and 0.77 cm^(3)/g,respectively.At a reaction temperature of 700℃ and an ethane feed rate of 90 mL/min,the CNTs yield of Fe-Al hollow nano-spherical catalyst reached as high as 48.6 gCNT/gcat,which was 1.8 and 4.6 times higher than the yield of irregular-shaped(27.7 gCNT/gcat)and micro-spherical(10.5 gCNT/gcat)catalysts,respectively.This was mainly attributed to the hollow cavity structure of Fe-Al catalyst providing sufficient space for the CNTs growth.As a result,the blockage of catalyst internal pores was prevented by the formed CNTs,which isolated ethane molecules from the active sites and lead to catalyst deactivation.Furthermore,the CNTs synthesized by Fe-Al hollow nano-spherical catalyst exhibited a uniform diameter distribution and a higher degree of graphitization.
文摘The effects of carbon dioxide content on the catalytic performance and coke formation of nickel catalyst supported on mesoporous nanocrystalline zirconia with high surface area and pure tetragonal crystalline phase were investigated in methane reforming with carbon dioxide. The samples were characterized by XRD, BET, TPR, TPO, TPH, TEM, and SEM techniques. The catalyst prepared showed high surface area and a mesoporous structure with a narrow pore size distribution. The obtained results revealed that the increase in CO2 content increased the methane conversion and stability of the catalyst and significantly reduced the coke deposition. The TPH analysis showed that several species of carbon with different reactivities toward hydrogenation were deposited on the spent catalysts employed under different CO2 contents.
文摘Cu/ZrO2 catalysts for methanol synthesis from CO2/H2 were respectively prepared by deposition coprecipitation （DP） and solid state reaction （SR） methods. There is an intimate interaction between copper and zirconia, which strongly affects the reduction property and catalytic performance of the catalysts. The stronger the interaction, the lower the reduction temperature and the better the performance of the catalysts. Surface area, pore structure and crystal structure of the catalysts are mainly controlled by preparation methods and alkalinity of synthesis system. The conversion of CO2 and selectivity of methanol are higher for DP catalysts than for SP catalysts.
文摘The introduction of mesoporous nanosize zirconia to the catalyst for methanol synthesis dedicates the nanosized catalyst and mesoporous duplicated properties. The catalyst bears the larger surface area, larger mesoporous volume and more uniform diameter, more surface metal atoms and oxygen vacancies than the catalyst prepared with the conventional coprecipitation method. The modification of microstructure and electronic effect could result in the change of the reduced chemical state and decrease of reducuction temperature of copper, donating the higher activity and methanol selectivity to the catalyst. The results of methanol synthesis demonstrate that the Cu^＋ is the optimum active site. Also, the interaction between the copper and zirconia shows the synergistic effect to fulfil the methanol synthesis.
基金the National Natural Science Foundation of China(No.21876206)the Shandong Key Fundamental Research Project(No.ZR202010280003)+1 种基金the Fundamental Research Funds for the Central Universities(No.18CX02037A)the Youth Innovation and Technology project of Universities in Shandong Province(No.2020KJC007).
文摘Colorimetry often suffers from deficiency in quantitative determination,susceptibility to ambient illuminance,and low sensitivity and visual resolution to tiny color changes.To offset these deficiencies,we incorporate deep machine learning into colorimetry by introducing a convolutional neural network(CNN)with powerful parallel processing,self-organization,and self-learning capabilities.As a proof of concept,a plasmonic nanosensor is proposed for the colorimetric detection of glucose by coupling Benedict’s reagent with gold nanoparticles(AuNPs),which relies on the assemble of AuNPs into dendritic nanochains by Cu2O.The distinct difference of refractive index between Cu2O and Au and the localized surface plasmon resonance coupling effect among AuNPs leads to a broad spectral shift as well as abundant color changes,thereby providing sufficient data for selflearning enabled by machine learning.The CNN is then used to fully diversify the learning and training of the images from standard samples under different ambient conditions and to obtain a classifier that can not only recognize tiny color changes that are imperceptible to human eyes,but also exhibit high accuracy and excellent anti-environmental interference capability.This classifier is then compiled as an application(APP)and implanted into a smartphone with Android environment.306 clinical urine samples were detected using the proposed method and the results showed a satisfactory correlation(87.6%)with that of a standard blood glucose test method.More importantly,this method can be generalized to other applications in colorimetry,and more broadly,in other scientific domains that involve image analysis and quantification.
基金We thank Prof. Mingbo Wu （State Key Laboratory of Heavy Oil Processing, China University of Petroleum） for his help in experiments. This work was finandally supported by the Key Joint Foundation of PetroChina, the National Natural Science Foundation of China （Nos. 51271215, U1362202, and 21106185） and the PetroChina Key Programs on Oil Refinery Catalysts （No. 2010E-1908 and 2010E-1903）.
文摘The careful design of nano-architectures and smart hybridization of expected active materials can lead to more advanced properties. Here we have engineered a novel hierarchical branching Cu/Cu2O/CuO heteronanostructure by combining a facile hydrothermal method and subsequent controlled oxidation process. The fine structure and epitaxial relationship between the branches and backbone are investigated by high-resolution transmission electron microscopy. Moreover, the evolution of the branch growth has also been observed during the gradual oxidation of the Cu nanowire surface. The experimental results suggest that the surface oxidation needs to be performed via a two-step exposure process to varying humidity in order to achieve optimized formation of a core-shell structured branching architecture. Finally, a proof-of-concept of the function of such a hierarchical framework as the anode material in lithium-ion batteries is demonstrated. The branching core-shell heterostructure improves battery performance by several means： （i） The epitaxially grown branches provide a high surface area for enhanced electrolyte accessibility and high resistance to volume change induced by Li^＋ intercalation/extraction; （ii） the core-shell structure with its well-defined heterojunction increases the contact area which facilitates effective charge transport during lithiation; （iii） the copper core acts as a current collector as well as providing structural reinforcement.
基金financially supported by the National Natural Science Foundation of China (51271215 and 21601133)Sinopec Innovation Scheme (A-381)
文摘Porous niobium oxide nanowires synthesized via a solvothermal method exhibited decreased bandgap,en- hanced light absorption and reduced charge-recombination rate.The porous Nb2O5 nanowires showed increased performance for the photocatalytic H2 evolution and photo- degradation of rhodamine B,as compared to their solid counterparts,which could be ascribed to the peculiar porous nanostructure.
基金Project supproted by University of Queensland, Australia.
文摘Based on a general classification and characteristic comparison of the existing models, a new model for non-catalytic gas-solid reactions is proposed and a general formulation for the model in terms of the solid conversion, X, is presented in mis paper. The model, referred to the generalized model, is demonstrated to be applicable to any solid reactant of general structure ranging from highly porous to nonporous materials. It is shown that the generalized model incorporates the grain and pore structure for a solid pellet and can be reduced to the grain and random pore models as extreme cases.
文摘Copper nanorods have been synthe-sized in mesoporous SBA-15 by a low-temperature metal organic chemical vapor deposition (MOCVD) employing copper (II) acetylacetonate, Cu(acac)2, and hydrogen as a precursor and reactant gas, re- spectively. The hydrogen plays an important role in chemical reduction of oganometallic precursor which enhances mass transfer in the interior of the SBA-15 porous substrate. Such copper nanostructures are of great potentials in the semiconductor due to their unusual optical, magnetic and electronic properties. In addition, it has been found that chemically modi- fying the substrate surface by carbon deposition is crucial to such synthesis of copper nanostructures in the interior of the SBA-15, which is able to change the surface properties of SBA-15 from hydrophilic to hydrophobic to promote the adsorption of organic cupric precursor. It has also been found that the copper nanoparticles deposited on the external sur- face are almost eliminated and the copper nanorods are more distinct while the product was treated with ammonia. This approach could be achieved under a mild condition: a low temperature (400℃) and vac-uum (2 kPa) which is extremely milder than the con- ventional method. It actually sounds as a foundation which is the first time to synthesize a copper nanorod at a mild condition of a low reaction temperature and pressure.
文摘The ordered carbon nanorods (OCNR) was successfully synthesized using the mesoporous silica as hard template. XRD tests and TEM observations showed that OCNR was composed of arrayed carbon nanorods in the p6mm symmetry. N2 sorption analysis demonstrated that OCNR possessed the typically mesoporous structure and centralized mesopore distribution. Compared with Maxsorb, an active carbon with super high surface area, OCNR has superior capacitive behavior, power output and high fre- quency performance due to its ordered pore-structure, which favors the fast diffusion of hydrated ions. As evidenced by cyclic voltammetry measurements, OCNR shows superior capacitive behaviors (exhibiting a high capacitance of 166 F/g even at very high sweep rate of 50 mV/s, as compared to much reduced capacitance of 73 F/g for Maxsorb at the same sweep rate). OCNR can provide much higher power density while still maintaining good energy density, which offers a great potential in electrochemical double layer ca- pacitor (EDLC), particularly for applications where both high power output and energy density are required.
基金Supported by the Australian Research Council (ARC) through Discovery Project program (DP0452461)
文摘Carbon nanotubes (CNTs)/mesostructured silica core-shell nanowires with a carbon nanotube core and controllable highly ordered periodic mesoporous silica shell are syntheiszed via the interfacial surfac- tant template. The core-shell nanowires are characterized by transmission electron microscope (TEM), X-ray diffraction pattern (XRD) and nitrogen sorption/desorption. The results indicate that the core-shell nanowires have highly ordered periodic mesoporous silica shell (space group p6mm), high BET sur- face area and narrow pore size distribution. Moreover, the morphology of core-shell nanowires can be controlled by the pH value. The core-shell nanowires have promising applications in biosensors, nanoprobes and energy storage due to their good dispersibility in polar solvents.
基金supported by grants from the Program of Science and Technology Bureau of Qingdao(NO.08-1-3-14-JCH).
文摘Tree-like SnO_(2) nanodendrites in large amounts have been prepared through two-step reactions.The nanoparticles used as the precursors have taken aggrega-tion forming tree-like or string of nanodendrtie.The samples were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),high-resolution transmission electron microscopy(HRTEM)and energy dispersive spectrometer(EDS),respectively.The results showed that molar ratio of the ethanol/distilled water is an important factor for formation of the different dendrite structures.There are different morphologies between tree-like SnO_(2) nanowhiskers and bunch of SnO_(2) nanorods.However,they are growing along the [112].
