The support materials are an important part of catalysts and they are the dispersant,adhesive,and support for other components.In this study,three types of thin films with different structures were used as the precurs...The support materials are an important part of catalysts and they are the dispersant,adhesive,and support for other components.In this study,three types of thin films with different structures were used as the precursor to prepare loading Pd catalysts.The one-step dealloying method was used to prepare a semiconductor nanofiber film(NFF)support material with upward directional growth from the substrate.Pd/NFF and Pd/Ni O/NFF loaded Pd catalysts were prepared using NFF as the support material,and the electrochemical catalytic properties for ethanol oxidation in alkaline media were studied.Cyclic votammetry showed that the NFF support material effectively inhibited agglomeration of palladium,increased the number of active sites of Pd,and improved the electrocatalytic properties of Pd for ethanol oxidation.In addition,the Pd/Ni O/NFF loaded Pd catalyst obtained by modification with nickel oxide significantly improved the electrocatalytic performance for ethanol oxidation compared with the Pd/NFF loaded Pd catalyst.These results show that Ni O is conductive to absorption of oxygen-containing groups on the surface of the catalyst and can further improve the electrocatalytic ability of Pd for ethanol oxidation.All of the above results demonstrate that the support material prepared by the dealloying method has application prospects in load-type catalysts.展开更多
Nuclear fuel cell calculation is one of the most complicated steps of neutron transport problems in the reactor core. A few numerical methods use neutron flat flux (FF) approximation to solve this problem. In this app...Nuclear fuel cell calculation is one of the most complicated steps of neutron transport problems in the reactor core. A few numerical methods use neutron flat flux (FF) approximation to solve this problem. In this approach, neutron flux spectrum is assumed constant in each region. The solution of neutron transport equation using collision probability (CP) method based on non flat flux (NFF) approximation by introducing linear spatial distribution function implemented to a simple cylindrical annular cell has been carried out. In this concept, neutron flux spectrum in each region is different each other because of an existing of the spatial function. Numerical calculation of the neutron flux in each region of the cell using NFF approach shows a fairly good agreement compared to those calculated using existing SRAC code and FF approach. Moreover, calculation of the neutron flux in each region of the nuclear fuel cell using NFF approach needs only 6 meshes which give equivalent result when it is calculated using 24 meshes in FF approach. This result indicates that NFF approach is more efficient to be used to calculate the neutron flux in the regions of the cell than FF approach.展开更多
基金supported financially by the National Natural Science Foundation of China(No.51801050)the National Key Research and Development Project(No.2016YFB0300500)+1 种基金the Fundamental Research Funds for the Central Universities(No.JZ2019HGBZ0188)the Fundamental Research Funds for the Central Universities(No.JZ2016HGPB0671)。
文摘The support materials are an important part of catalysts and they are the dispersant,adhesive,and support for other components.In this study,three types of thin films with different structures were used as the precursor to prepare loading Pd catalysts.The one-step dealloying method was used to prepare a semiconductor nanofiber film(NFF)support material with upward directional growth from the substrate.Pd/NFF and Pd/Ni O/NFF loaded Pd catalysts were prepared using NFF as the support material,and the electrochemical catalytic properties for ethanol oxidation in alkaline media were studied.Cyclic votammetry showed that the NFF support material effectively inhibited agglomeration of palladium,increased the number of active sites of Pd,and improved the electrocatalytic properties of Pd for ethanol oxidation.In addition,the Pd/Ni O/NFF loaded Pd catalyst obtained by modification with nickel oxide significantly improved the electrocatalytic performance for ethanol oxidation compared with the Pd/NFF loaded Pd catalyst.These results show that Ni O is conductive to absorption of oxygen-containing groups on the surface of the catalyst and can further improve the electrocatalytic ability of Pd for ethanol oxidation.All of the above results demonstrate that the support material prepared by the dealloying method has application prospects in load-type catalysts.
文摘Nuclear fuel cell calculation is one of the most complicated steps of neutron transport problems in the reactor core. A few numerical methods use neutron flat flux (FF) approximation to solve this problem. In this approach, neutron flux spectrum is assumed constant in each region. The solution of neutron transport equation using collision probability (CP) method based on non flat flux (NFF) approximation by introducing linear spatial distribution function implemented to a simple cylindrical annular cell has been carried out. In this concept, neutron flux spectrum in each region is different each other because of an existing of the spatial function. Numerical calculation of the neutron flux in each region of the cell using NFF approach shows a fairly good agreement compared to those calculated using existing SRAC code and FF approach. Moreover, calculation of the neutron flux in each region of the nuclear fuel cell using NFF approach needs only 6 meshes which give equivalent result when it is calculated using 24 meshes in FF approach. This result indicates that NFF approach is more efficient to be used to calculate the neutron flux in the regions of the cell than FF approach.
