利用抗坏血酸对AgNO3进行还原，生成银纳米粒核心，并通过正硅酸四乙酯的水解与聚合反应获得SiO2介孔外壳，制备平均粒径约为.9 nm的Ag SiO2核壳型纳米粒。 Ag SiO2纳米粒可以显著地抑制香石竹镰刀菌的生长，最小抑菌质量浓度为μg/mL...利用抗坏血酸对AgNO3进行还原，生成银纳米粒核心，并通过正硅酸四乙酯的水解与聚合反应获得SiO2介孔外壳，制备平均粒径约为.9 nm的Ag SiO2核壳型纳米粒。 Ag SiO2纳米粒可以显著地抑制香石竹镰刀菌的生长，最小抑菌质量浓度为μg/mL，并可抑制香石竹镰刀菌菌丝生长和孢子分生。 Ag SiO2纳米粒处理～4 h后，菌丝体的过氧化氢酶、总超氧化物歧化酶、过氧化物酶活力增强，提示Ag SiO2纳米粒抗菌机制和活性氧诱导相关。展开更多
We have prepared and characterized atomically well-defined model systems for ceria-supported Pt-Co core-shell catalysts. Pt@Co and Co@Pt core-shell nanostructures were grown on well-ordered CeO2(111) films on Cu(111) ...We have prepared and characterized atomically well-defined model systems for ceria-supported Pt-Co core-shell catalysts. Pt@Co and Co@Pt core-shell nanostructures were grown on well-ordered CeO2(111) films on Cu(111) by physical vapour deposition of Pt and Co metals in ultrahigh vacuum and investigated by means of synchrotron radiation photoelectron spectroscopy and resonant photoemission spectroscopy. The deposition of Co onto CeO2(111) yields CoCeO2(111) solid solution at low Co coverage(0.5 ML), followed by the growth of metallic Co nanoparticles at higher Co coverages. Both Pt@Co and Co@Pt model structures are stable against sintering in the temperature range between 300 and 500 K. After annealing at 500 K, the Pt@Co nanostructure contains nearly pure Co-shell while the Pt-shell in the Co@Pt is partially covered by metallic Co. Above 550 K, the re-ordering in the near surface regions yields a subsurface Pt-Co alloy and Pt-rich shells in both Pt@Co and Co@Pt nanostructures. In the case of Co@Pt nanoparticles, the chemical ordering in the near surface region depends on the initial thickness of the deposited Pt-shell. Annealing of the Co@Pt nanostructures in the presence of O2 triggers the decomposition of Pt-Co alloy along with the oxidation of Co, regardless of the thickness of the initial Pt-shell. Progressive oxidation of Co coupled with adsorbate-induced Co segregation leads to the formation of thick CoO layers on the surfaces of the supported Co@Pt nanostructures. This process is accompanied by the disintegration of the CeO2(111) film and encapsulation of oxidized Co@Pt nanostructures by CeO2 upon annealing in O2 above 550 K. Notably, during oxidation and reduction cycles with O2 and H2 at different temperatures, the changes in the structure and chemical composition of supported Co@Pt nanostructures were driven mainly by oxidation while reduction treatments had little effect regardless of the initial thickness of the Pt-shell.展开更多
文摘利用抗坏血酸对AgNO3进行还原，生成银纳米粒核心，并通过正硅酸四乙酯的水解与聚合反应获得SiO2介孔外壳，制备平均粒径约为.9 nm的Ag SiO2核壳型纳米粒。 Ag SiO2纳米粒可以显著地抑制香石竹镰刀菌的生长，最小抑菌质量浓度为μg/mL，并可抑制香石竹镰刀菌菌丝生长和孢子分生。 Ag SiO2纳米粒处理～4 h后，菌丝体的过氧化氢酶、总超氧化物歧化酶、过氧化物酶活力增强，提示Ag SiO2纳米粒抗菌机制和活性氧诱导相关。
基金funded by the European Community(FP7-NMP.2012.1.1-1 project chip CAT,Reference No.310191)by the Deutsche Forschungsgemeinschaft(DFG)within the Excellence Cluster“Engineering of Advanced Materials”in the framework of the excellence initiative+2 种基金support by the DFG is acknowledged through the Priority Program SPP 1708 and the Research Unit FOR 1878supported by structural funds under project CZ.02.1.01/0.0/0.0/16_025/0007414by the Czech Ministry of Education(grant LM2015057)。
文摘We have prepared and characterized atomically well-defined model systems for ceria-supported Pt-Co core-shell catalysts. Pt@Co and Co@Pt core-shell nanostructures were grown on well-ordered CeO2(111) films on Cu(111) by physical vapour deposition of Pt and Co metals in ultrahigh vacuum and investigated by means of synchrotron radiation photoelectron spectroscopy and resonant photoemission spectroscopy. The deposition of Co onto CeO2(111) yields CoCeO2(111) solid solution at low Co coverage(0.5 ML), followed by the growth of metallic Co nanoparticles at higher Co coverages. Both Pt@Co and Co@Pt model structures are stable against sintering in the temperature range between 300 and 500 K. After annealing at 500 K, the Pt@Co nanostructure contains nearly pure Co-shell while the Pt-shell in the Co@Pt is partially covered by metallic Co. Above 550 K, the re-ordering in the near surface regions yields a subsurface Pt-Co alloy and Pt-rich shells in both Pt@Co and Co@Pt nanostructures. In the case of Co@Pt nanoparticles, the chemical ordering in the near surface region depends on the initial thickness of the deposited Pt-shell. Annealing of the Co@Pt nanostructures in the presence of O2 triggers the decomposition of Pt-Co alloy along with the oxidation of Co, regardless of the thickness of the initial Pt-shell. Progressive oxidation of Co coupled with adsorbate-induced Co segregation leads to the formation of thick CoO layers on the surfaces of the supported Co@Pt nanostructures. This process is accompanied by the disintegration of the CeO2(111) film and encapsulation of oxidized Co@Pt nanostructures by CeO2 upon annealing in O2 above 550 K. Notably, during oxidation and reduction cycles with O2 and H2 at different temperatures, the changes in the structure and chemical composition of supported Co@Pt nanostructures were driven mainly by oxidation while reduction treatments had little effect regardless of the initial thickness of the Pt-shell.
