The cementation of copper ions from aqueous copper sulfate solutions by using spherical aluminum metal particles was examined. The effects of the experimental parameters on copper cementation were investigated and eva...The cementation of copper ions from aqueous copper sulfate solutions by using spherical aluminum metal particles was examined. The effects of the experimental parameters on copper cementation were investigated and evaluated. Reaction rate increases with increasing copper concentration, reaction temperature, stirring speed and decreasing pH. It was observed that the reaction follows the first-order kinetics, and progresses according to the diffusion controlling step.展开更多
The performance of fuel-cell related electrocatalysis is highly dependent on the morphology,size and composition of a given catalyst.In terms of rational design of Pt-based catalyst,one-dimensional(1 D)ultrafine Pt al...The performance of fuel-cell related electrocatalysis is highly dependent on the morphology,size and composition of a given catalyst.In terms of rational design of Pt-based catalyst,one-dimensional(1 D)ultrafine Pt alloy nanowires(NWs)are considered as a commendable model for enhanced catalysis on account of their favorable mass/charge transfer and structural durability.However,in order to achieve the noble metal catalysts in higher efficiency and lower cost,building high-index facets and shaping hollow interiors should be integrated into 1 D Pt alloy NWs,which has rarely been done so far.Here,we report the first synthesis of a class of spiny Pd/PtFe core/shell nanotubes(SPCNTs)constructed by cultivating PtFe alloy branches with rich high-index facets along the 1 D removable Pd supports,which is driven by the galvanic dissolution of Pd substrates concomitant with Stranski-Krastanov(S-K)growth of Pt and Fe,for achieving highly efficient fuel-cells-related electrocatalysis.This new catalyst can even deliver electrochemical active surface area(ECSA)of 62.7 m^(2)gPt^(-1),comparable to that of commercial carbonsupported Pt nanoparticles.With respect to oxygen reduction catalysis,the SPCNTs showcase the remarkable mass and specific activity of 2.71 A mg^(-1)and 4.32 mA cm^(-2),15.9 and 16.0 times higher than those of commercial Pt/C,respectively.Also,the catalysts exhibit extraordinary resistance to the activity decay and structural degradation during 50,000 potential cycles.Moreover,the SPCNTs serve as a category of efficient and stable catalysts towards anodic alcohol oxidation.展开更多
The exchange bias is of technological significance in magnetic recording and spintronic devices.Pursuing a large bias field is a long-term goal for the research field of magnetic shape memory alloys.In this work,a lar...The exchange bias is of technological significance in magnetic recording and spintronic devices.Pursuing a large bias field is a long-term goal for the research field of magnetic shape memory alloys.In this work,a large bias field of 0.53 T is achieved in the Ni50Mn34In16-xFex(x=1,3,5)system by tuning the magnetic ground state(determined by the composition x)and the magnetic-field history(determined by the magnetic field HFCduring field cooling and the maximum field HMaxduring isothermal magnetization).The maximum volume fraction of the interfaces between the ferromagnetic clusters and antiferromagnetic matrix and the strong interfacial interaction are achieved by tuning the magnetic ground state and the magnetic-field history,which results in strong magnetic unidirectional anisotropy and the large exchange bias.Moreover,two guidelines were proposed to obtain the large bias field.Firstly,the composition with a magnetic ground state consisting of the dilute spin glass and the strong antiferromagnetic matrix is preferred to obtain a large bias field;secondly,tuning the magnetic-field history by enhancing HFCand reducing HMaxis beneficial to achieving large exchange bias.Our work provides an effective way for designing magnetically inhomogeneous compounds with large exchange bias.展开更多
基金Project (2008/55) supported by Inonu University Research Fund, Turkey
文摘The cementation of copper ions from aqueous copper sulfate solutions by using spherical aluminum metal particles was examined. The effects of the experimental parameters on copper cementation were investigated and evaluated. Reaction rate increases with increasing copper concentration, reaction temperature, stirring speed and decreasing pH. It was observed that the reaction follows the first-order kinetics, and progresses according to the diffusion controlling step.
基金the Xplorer Prize,the Beijing Natural Science Foundation(JQ18005,Z190010)the National Natural Science Foundation of China(NSFC)(51671003,and 21771156)+3 种基金National R&D Program of China(2017YFA0206701)the China Postdoctoral Science Foundation(2019M660290)the state Key Laboratory of Solidification Processing in NPU(SKLSP202004)the Start-up supports from Peking University and Young Thousand Talented Program.
文摘The performance of fuel-cell related electrocatalysis is highly dependent on the morphology,size and composition of a given catalyst.In terms of rational design of Pt-based catalyst,one-dimensional(1 D)ultrafine Pt alloy nanowires(NWs)are considered as a commendable model for enhanced catalysis on account of their favorable mass/charge transfer and structural durability.However,in order to achieve the noble metal catalysts in higher efficiency and lower cost,building high-index facets and shaping hollow interiors should be integrated into 1 D Pt alloy NWs,which has rarely been done so far.Here,we report the first synthesis of a class of spiny Pd/PtFe core/shell nanotubes(SPCNTs)constructed by cultivating PtFe alloy branches with rich high-index facets along the 1 D removable Pd supports,which is driven by the galvanic dissolution of Pd substrates concomitant with Stranski-Krastanov(S-K)growth of Pt and Fe,for achieving highly efficient fuel-cells-related electrocatalysis.This new catalyst can even deliver electrochemical active surface area(ECSA)of 62.7 m^(2)gPt^(-1),comparable to that of commercial carbonsupported Pt nanoparticles.With respect to oxygen reduction catalysis,the SPCNTs showcase the remarkable mass and specific activity of 2.71 A mg^(-1)and 4.32 mA cm^(-2),15.9 and 16.0 times higher than those of commercial Pt/C,respectively.Also,the catalysts exhibit extraordinary resistance to the activity decay and structural degradation during 50,000 potential cycles.Moreover,the SPCNTs serve as a category of efficient and stable catalysts towards anodic alcohol oxidation.
基金supported by the National Natural Science Foundation of China(51471127,51431007 and 51371134)the Program for Young Scientific New-star in Shaanxi Province of China(2014KJXX-35)+2 种基金the Innovation Capability Support Program of Shaanxi(2018PT-28 and 2017KTPT-04)Shenzhen Science and Technology Project(JCYJ20180507182246321)the Fundamental Research Funds for Central Universities of China。
文摘The exchange bias is of technological significance in magnetic recording and spintronic devices.Pursuing a large bias field is a long-term goal for the research field of magnetic shape memory alloys.In this work,a large bias field of 0.53 T is achieved in the Ni50Mn34In16-xFex(x=1,3,5)system by tuning the magnetic ground state(determined by the composition x)and the magnetic-field history(determined by the magnetic field HFCduring field cooling and the maximum field HMaxduring isothermal magnetization).The maximum volume fraction of the interfaces between the ferromagnetic clusters and antiferromagnetic matrix and the strong interfacial interaction are achieved by tuning the magnetic ground state and the magnetic-field history,which results in strong magnetic unidirectional anisotropy and the large exchange bias.Moreover,two guidelines were proposed to obtain the large bias field.Firstly,the composition with a magnetic ground state consisting of the dilute spin glass and the strong antiferromagnetic matrix is preferred to obtain a large bias field;secondly,tuning the magnetic-field history by enhancing HFCand reducing HMaxis beneficial to achieving large exchange bias.Our work provides an effective way for designing magnetically inhomogeneous compounds with large exchange bias.
