Alloying metals to form intermetallics has been proven effective in tuning the chemical properties of metal-based catalysts.However,intermetallic alloys can undergo structural and chemical transformations under reacti...Alloying metals to form intermetallics has been proven effective in tuning the chemical properties of metal-based catalysts.However,intermetallic alloys can undergo structural and chemical transformations under reactive conditions,leading to changes in their catalytic function.Elucidating and understanding these transformations are crucial for establishing relevant structureperformance relationships and for the rational design of alloy-based catalysts.In this work,we used CuZn alloy nanoparticles(NPs)as a model material system and employed in situ transmission electron microscopy(TEM)to investigate the structural and chemical changes of CuZn NPs under H_(2),O_(2)and their mixture.Our results show how CuZn NPs undergo sequential transformations in the gas mixture at elevated temperatures,starting with gradual leaching and segregation of Zn,followed by oxidation at the NP surface.The remaining copper at the core of particles can then engage in dynamic behavior,eventually freeing itself from the zinc oxide shell.The structural dynamics arises from an oscillatory phase transition between Cu and Cu_(2)O and is correlated with the catalytic water formation,as confirmed by in situ mass spectrometry(MS).Under pure H_(2)or O_(2)atmosphere,we observe different structural evolution pathways and final chemical states of CuZn NPs compared to those in the gas mixture.These results clearly demonstrate that the chemical state of alloy NPs can vary considerably under reactive redox atmospheres,particularly for those containing elements with distinct redox properties,necessitating the use of in situ or detailed ex situ characterizations to gain relevant insights into the states of intermetallic alloy-based catalysts and structure-activity relationships.展开更多
Diatomic site catalysts(DACs)with two adjacent atomic metal species can provide synergistic interactions and more sophisticated functionalities to break the bottleneck of intrinsic drawbacks of single atom catalysts(S...Diatomic site catalysts(DACs)with two adjacent atomic metal species can provide synergistic interactions and more sophisticated functionalities to break the bottleneck of intrinsic drawbacks of single atom catalysts(SACs).Herein,we have designed a CuZn diatomic site(CuZn-DAS)electrocatalyst with unique coordination structure(CuN_(4)-ZnN_(4))by anchoring and ordering the spatial distance between the metal precursors on the carbon nitride(C_(3)N_(4))derived N-doped carbon(NC)substrate.The CuZn-DAS/NC shows high activity and selectivity for electroreduction CO_(2)into CO.The Faradaic efficiency for CO of CuZn-DAS/NC(98.4%)is higher than that of Cu single atomic site on NC(Cu-SAS/NC)(36.4%)and Zn single atomic site on NC(Zn-SAS/NC)(66.8%)at-0.6 V versus reversible hydrogen electrode(vs.RHE).In situ characterizations reveal that the CuZn-DAS is more favorable for the formation and adsorption of^(*)COOH than those of the electrocatalysts with single atomic site.Theorical calculations show that the charge redistribution of Zn site in CuZn-DAS/NC caused by the considerable electron transfers from Zn atoms to the adjacent Cu atoms can reduce the adsorption energy barriers for^(*)COOH and^(*)CO production,improving the activity and CO selectivity.展开更多
Uncontrollable dendrite growth and side reactions resulting in short operating life and low Coulombic efficiency have severely hindered the further development of aqueous zinc-ion batteries(AZIBs).In this work,we desi...Uncontrollable dendrite growth and side reactions resulting in short operating life and low Coulombic efficiency have severely hindered the further development of aqueous zinc-ion batteries(AZIBs).In this work,we designed to grow zeolitic imidazolate framework-8(ZIF-8)uniformly on CuO nanosheets(NSs)and prepared carbon-coated CuZn alloy NSs(CuZn@C NSs)by calcination under H_(2)/Ar atmosphere.As reflected by extended X-ray absorption fine structure(EXAFS),density functional theory(DFT),in-situ Raman,the Cu–Zn and Zn–N bonds present in CuZn@C NSs act as zincophilic sites to uniformly absorb Zn ions and inhibit the formation of Zn dendrites.At the same time,CuZn@C NSs hinder the direct contact between zinc anode and electrolyte,preventing the occurrence of side reactions.More impressively,the symmetric cells constructed with CuZn@C NSs anodes exhibited excellent zinc plating/exfoliation performance and long life cycle at different current densities with low voltage hysteresis.In addition,low polarization,high capacity retention,long cycle life over 1000 cycles at 5 A∙g^(−1) were achieved when CuZn@C NSs were used as anodes for CuZn@C/V_(2)O_(5)full cells.展开更多
The texture of 80% cold rolling CuZn ordered alloy was investigated. The development of rolling texturein 50%Cu-50%Zn(at.) alloy has been characterized by a inhomogenous {111} fiber texture with strong {111} <112&g...The texture of 80% cold rolling CuZn ordered alloy was investigated. The development of rolling texturein 50%Cu-50%Zn(at.) alloy has been characterized by a inhomogenous {111} fiber texture with strong {111} <112>component, which is significantly different from the conventional Cu-Zn alloys. The main characters of cold rollingtextures in ordered CuZn alloy are obviously similar to that in IF steel with bcc structure or ordered Fe3A1-basedalloys with imperfect B2 structure. From the rolling texture obtained by experiments and simulations,it can be estimated that main deformation mechanism are characterized by the activation of slip systems with <111> Burgersvector in CuZn ordered alloy.展开更多
The relationship among annealing temperature, microstructure and electrical resistivity of Cu (8%～13%)Zn (mole fraction) alloys was studied. The results show that the relationship between the electrical resistivity o...The relationship among annealing temperature, microstructure and electrical resistivity of Cu (8%～13%)Zn (mole fraction) alloys was studied. The results show that the relationship between the electrical resistivity of cold deformation CuZn alloy and annealing temperature is related to the recovery and recrystallization of the processes. The increments of electrical resistivity due to strain are restored mainly on the process of recovery and recrystallization. The room temperature resistivity of soft state alloys is linear to the Zn contents. The extended application of Matthissen rule on high concentration solid solution was discussed. [展开更多
A new Fe-SOD gene from a native Chinese tobacco germplasm namely HZNH has been successfully cloned and expressed. Full-length cDNA sequences of the Fe-SOD gene was obtained by employing the 5′ and 3′end RACE method ...A new Fe-SOD gene from a native Chinese tobacco germplasm namely HZNH has been successfully cloned and expressed. Full-length cDNA sequences of the Fe-SOD gene was obtained by employing the 5′ and 3′end RACE method from the HZNH′s cDNA library. The full sequence was 1145 bp in length, including 170 bp of 5′untranslated region, 288 bp of 3′untranslated region and 687 bp of coding region. The coding region encoded a peptide of 228 amino acid residues, in which there was a signal peptide with 26 amino acids and a mature peptide of 202 amino acids. The full-length cDNA sequence was compared with all other reported plants’ Fe-SOD genes’. The result of Blast analysis showed that they shared high homology(>80%) ,the highest one was to N. plumbaginifolia’s with the homology as high as 97.69%. This cDNA was constructed into the prokaryotic expression vector, pQE30a/FeSOD, and transformed into E.coli M15 which was induced with IPTG. SDS-PAGE showed that 27 kD proteins was expressed. The soluble proteins showed the Fe-SOD enzyme activities on PAGE-based isozyme spectrum indicating that this expressed soluble protein is indeed the Fe-SOD enzyme.展开更多
基金supported by the Swedish Research council under contract 2018-07152the Swedish Governmental Agency for Innovation Systems under contract 2018-04969+1 种基金Formas under contract 2019-02496X.H.thanks 1000 talent youth project,Fuzhou University and Qingyuan Innovation Laboratory for the financial support.
文摘Alloying metals to form intermetallics has been proven effective in tuning the chemical properties of metal-based catalysts.However,intermetallic alloys can undergo structural and chemical transformations under reactive conditions,leading to changes in their catalytic function.Elucidating and understanding these transformations are crucial for establishing relevant structureperformance relationships and for the rational design of alloy-based catalysts.In this work,we used CuZn alloy nanoparticles(NPs)as a model material system and employed in situ transmission electron microscopy(TEM)to investigate the structural and chemical changes of CuZn NPs under H_(2),O_(2)and their mixture.Our results show how CuZn NPs undergo sequential transformations in the gas mixture at elevated temperatures,starting with gradual leaching and segregation of Zn,followed by oxidation at the NP surface.The remaining copper at the core of particles can then engage in dynamic behavior,eventually freeing itself from the zinc oxide shell.The structural dynamics arises from an oscillatory phase transition between Cu and Cu_(2)O and is correlated with the catalytic water formation,as confirmed by in situ mass spectrometry(MS).Under pure H_(2)or O_(2)atmosphere,we observe different structural evolution pathways and final chemical states of CuZn NPs compared to those in the gas mixture.These results clearly demonstrate that the chemical state of alloy NPs can vary considerably under reactive redox atmospheres,particularly for those containing elements with distinct redox properties,necessitating the use of in situ or detailed ex situ characterizations to gain relevant insights into the states of intermetallic alloy-based catalysts and structure-activity relationships.
基金This study was supported by the National Natural Science Foundation of China(Nos.52073124 and 52273058)the Natural Science Foundation of Jiangsu Province(No.SBK2022030167)+1 种基金the MOE&SAFEA,111 Project(No.B13025)the Fundamental Research Funds for the Central Universities.
文摘Diatomic site catalysts(DACs)with two adjacent atomic metal species can provide synergistic interactions and more sophisticated functionalities to break the bottleneck of intrinsic drawbacks of single atom catalysts(SACs).Herein,we have designed a CuZn diatomic site(CuZn-DAS)electrocatalyst with unique coordination structure(CuN_(4)-ZnN_(4))by anchoring and ordering the spatial distance between the metal precursors on the carbon nitride(C_(3)N_(4))derived N-doped carbon(NC)substrate.The CuZn-DAS/NC shows high activity and selectivity for electroreduction CO_(2)into CO.The Faradaic efficiency for CO of CuZn-DAS/NC(98.4%)is higher than that of Cu single atomic site on NC(Cu-SAS/NC)(36.4%)and Zn single atomic site on NC(Zn-SAS/NC)(66.8%)at-0.6 V versus reversible hydrogen electrode(vs.RHE).In situ characterizations reveal that the CuZn-DAS is more favorable for the formation and adsorption of^(*)COOH than those of the electrocatalysts with single atomic site.Theorical calculations show that the charge redistribution of Zn site in CuZn-DAS/NC caused by the considerable electron transfers from Zn atoms to the adjacent Cu atoms can reduce the adsorption energy barriers for^(*)COOH and^(*)CO production,improving the activity and CO selectivity.
基金the National Natural Science Foundation of China(Nos.NSFC-U1904215,21805192,and 12102422)the Natural Science Foundation of Jiangsu Province(No.BK20200044)+2 种基金the Top-notch Academic Programs Project(TAPP)of Jiangsu Higher Education Institutions,and the Program for Young Changjiang Scholars of the Ministry of Education,China(No.Q2018270)We also acknowledge the Priority Academic Program Development of Jiangsu Higher Education Institutions.Y.Y.L.acknowledges the Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110735)the Natural Science Research Project of Anhui Educational Committee for Excellent Young Scholars(No.2022AH030152).
文摘Uncontrollable dendrite growth and side reactions resulting in short operating life and low Coulombic efficiency have severely hindered the further development of aqueous zinc-ion batteries(AZIBs).In this work,we designed to grow zeolitic imidazolate framework-8(ZIF-8)uniformly on CuO nanosheets(NSs)and prepared carbon-coated CuZn alloy NSs(CuZn@C NSs)by calcination under H_(2)/Ar atmosphere.As reflected by extended X-ray absorption fine structure(EXAFS),density functional theory(DFT),in-situ Raman,the Cu–Zn and Zn–N bonds present in CuZn@C NSs act as zincophilic sites to uniformly absorb Zn ions and inhibit the formation of Zn dendrites.At the same time,CuZn@C NSs hinder the direct contact between zinc anode and electrolyte,preventing the occurrence of side reactions.More impressively,the symmetric cells constructed with CuZn@C NSs anodes exhibited excellent zinc plating/exfoliation performance and long life cycle at different current densities with low voltage hysteresis.In addition,low polarization,high capacity retention,long cycle life over 1000 cycles at 5 A∙g^(−1) were achieved when CuZn@C NSs were used as anodes for CuZn@C/V_(2)O_(5)full cells.
文摘The texture of 80% cold rolling CuZn ordered alloy was investigated. The development of rolling texturein 50%Cu-50%Zn(at.) alloy has been characterized by a inhomogenous {111} fiber texture with strong {111} <112>component, which is significantly different from the conventional Cu-Zn alloys. The main characters of cold rollingtextures in ordered CuZn alloy are obviously similar to that in IF steel with bcc structure or ordered Fe3A1-basedalloys with imperfect B2 structure. From the rolling texture obtained by experiments and simulations,it can be estimated that main deformation mechanism are characterized by the activation of slip systems with <111> Burgersvector in CuZn ordered alloy.
文摘The relationship among annealing temperature, microstructure and electrical resistivity of Cu (8%～13%)Zn (mole fraction) alloys was studied. The results show that the relationship between the electrical resistivity of cold deformation CuZn alloy and annealing temperature is related to the recovery and recrystallization of the processes. The increments of electrical resistivity due to strain are restored mainly on the process of recovery and recrystallization. The room temperature resistivity of soft state alloys is linear to the Zn contents. The extended application of Matthissen rule on high concentration solid solution was discussed. [
文摘A new Fe-SOD gene from a native Chinese tobacco germplasm namely HZNH has been successfully cloned and expressed. Full-length cDNA sequences of the Fe-SOD gene was obtained by employing the 5′ and 3′end RACE method from the HZNH′s cDNA library. The full sequence was 1145 bp in length, including 170 bp of 5′untranslated region, 288 bp of 3′untranslated region and 687 bp of coding region. The coding region encoded a peptide of 228 amino acid residues, in which there was a signal peptide with 26 amino acids and a mature peptide of 202 amino acids. The full-length cDNA sequence was compared with all other reported plants’ Fe-SOD genes’. The result of Blast analysis showed that they shared high homology(>80%) ,the highest one was to N. plumbaginifolia’s with the homology as high as 97.69%. This cDNA was constructed into the prokaryotic expression vector, pQE30a/FeSOD, and transformed into E.coli M15 which was induced with IPTG. SDS-PAGE showed that 27 kD proteins was expressed. The soluble proteins showed the Fe-SOD enzyme activities on PAGE-based isozyme spectrum indicating that this expressed soluble protein is indeed the Fe-SOD enzyme.
