Single-atom catalysts are of great interest and importance for designing new high-performance low-cost catalysts. We investigated CO oxidation catalyzed by single gold atoms supported on thoria （Au/ThO2） and doped T...Single-atom catalysts are of great interest and importance for designing new high-performance low-cost catalysts. We investigated CO oxidation catalyzed by single gold atoms supported on thoria （Au/ThO2） and doped ThO2 using density functional theory with Hubbard-type on-site Coulomb interaction （DFT ＋ U）. The calculation results show that the Au-doped THO2（111） catalyst exhibits remarkable catalytic activity for CO oxidation via the Eley-Rideal mechanism in three steps, where the rate-determining step is decomposition of the OCOO＋ intermediate with an energy barrier of 0.58 eV. Moreover, our results also reveal a new mechanism of CO oxidation on a gold adatom supported by THO2（111）, where O2 is adsorbed only at the Th site on the surface, and the gas-phase CO then reacts directly with the activated O2＋ to form CO2, which is the rate-limiting step, with a barrier of 0.46 eV. It is found that CO oxidation can occur without CO and O2 coadsorption on Au, which was previously considered a key intermediate. Therefore, these results provide new insights into CO oxidation on isolated gold atoms supported by the 5f-element compound THO2（111）. This mechanism can help clarify the catalytic cycle of CO oxidation, support the design of high- performance low-cost catalysts, and elucidate the redox properties of actinide oxides.展开更多
Neutron-deficient actinide nuclei provide a valuable window to probe heavy nuclear systems with large proton-neutron ratios. In recent years, several new neutron-deficient Uranium and Neptunium isotopes have been obse...Neutron-deficient actinide nuclei provide a valuable window to probe heavy nuclear systems with large proton-neutron ratios. In recent years, several new neutron-deficient Uranium and Neptunium isotopes have been observed using α-decay spectroscopy [Z. Y. Zhang et al., Phys. Rev. Lett. 122, 192503(2019);L. Ma et al., Phys. Rev.Lett. 125, 032502(2020);Z. Y. Zhang et al., Phys. Rev. Lett. 126, 152502(2021)]. In spite of these achievements,some neutron-deficient key nuclei in this mass region are still unknown in experiments. Machine learning algorithms have been applied successfully in different branches of modern physics. It is interesting to explore their applicability in α-decay studies. In this work, we propose a new model to predict the α-decay energies and half-lives within the framework based on a machine learning algorithm called the Gaussian process. We first calculate the α-decay properties of the new actinide nucleus 214 U. The theoretical results show good agreement with the latest experimental data, which demonstrates the reliability of our model. We further use the model to predict the α-decay properties of some unknown neutron-deficient actinide isotopes and compare the results with traditional models. The results may be useful for future synthesis and identification of these unknown isotopes.展开更多
Actinide elements encaged in a superatomic cluster can exhibit unique properties due to their hyperactive valence electrons. Herein, the electronic and spectroscopic properties of Th@Au14 are predicted and compared wi...Actinide elements encaged in a superatomic cluster can exhibit unique properties due to their hyperactive valence electrons. Herein, the electronic and spectroscopic properties of Th@Au14 are predicted and compared with that of the isoelectronic entities [Ac@Au14]- and [Pa@Au14]＋ using density functional theory. The calculation results indicate that these clusters all adopt a closed- shell superatomic 18-electron configuration of the 1S21p61D10 Jellium state. The absorption spectrum of Th@Au14 can be interpreted by the Jelliumatic orbital model. In addition, calculated spectra of pyridine-Th@Au14 complexes in the blue laser band exhibit strong peaks attributable to charge transfer （CT） from the metal to the pyridine molecule. These charge-transfer bands lead to a resonant surface-enhanced Raman scattering （SERS） enhancement of -104. This work suggests a basis for designing and synthesizing SERS substrate materials based on actinide-embedded gold superatom models.展开更多
The complete-fusion reaction^(204)Pb(^(48)Ca,2n)^(250)No was used to study two activities of^(250)No with distinct half-lives.A total of 1357 events were observed in the SFiNx neutron detection system.The average numb...The complete-fusion reaction^(204)Pb(^(48)Ca,2n)^(250)No was used to study two activities of^(250)No with distinct half-lives.A total of 1357 events were observed in the SFiNx neutron detection system.The average number of neutrons emitted per spontaneous fission of^(250)No was determined to be(4.1±0.1).The unusually symmetrical shape of the prompt neutron multiplicity distribution was restored and presented for the first time.Statistical tests were performed to compare the prompt neutron multiplicity distributions associated with the ground state and K-isomer state decays.展开更多
Four novel compounds based on hexanuclear thorium cluster were synthesized and characterized.Compound 1[Th_(6)(HPy C)_(8)(HCOO)_(4)]is formed by replacing formate ligands of preassembled thorium cluster[Th_(6)O_(4)(OH...Four novel compounds based on hexanuclear thorium cluster were synthesized and characterized.Compound 1[Th_(6)(HPy C)_(8)(HCOO)_(4)]is formed by replacing formate ligands of preassembled thorium cluster[Th_(6)O_(4)(OH)_(4)(H_(2)O)_(6)(HCOO)_(12)]with eight H_(2)Py C(4-pyrazolecarboxylic acid)under solvothermal conditions.Each of the HPy C^(-)ligands is coordinated with one Cu^(2+)to form the(4,8)-connected scu-net structure of compound 2[(Cu Cl_(2))_(2)Th_(6)(HPy C)_8(HCOO)_(4)].In compound 3[(Cu Cl_(2))_(2)Th_(6)(HPy C)_(10)(HCOO)_(4)],ten of the formate ligands of preassembled Th_(6)cluster are replaced by HPy C^(-)ligands.Compared with compound 2,the two extra HPy C^(-)ligands in the equatorial plane of the Th_(6)cluster in compound 3 are not further connected to copper ions.Therefore,the topology structure of compound 3 is same with that of compound 2.Compound 4[(Cu_(3)Cl_(2))(Cu Cl_(2))Th_(6)(Py C)_(3)(HPy C)_(4)(HCOO)_(5)]contains three kinds of metal nodes,Th_(6)cluster,Cu_(3)cluster and mononuclear Cu^(2+),and exhibits a novel(5,7)-connected net structure,which was first discovered in actinide MOFs.Furthermore,considering the satisfactory stability of compound 4 and its unsaturated metal nodes and Lewis acid sites,the catalysis of cycloaddition of CO_(2)was further studied.We found that this thorium-copper heterometallic cluster organic framework can be used as a potential actinide functional material for catalyzing the efficient CO_(2)conversion to value-added products.展开更多
Crystalline coordination complexes of actinides,especially in atypical oxidation states,are not only fundamentally important for expanding the notably limited knowledge on the bonding nature of actinides but could als...Crystalline coordination complexes of actinides,especially in atypical oxidation states,are not only fundamentally important for expanding the notably limited knowledge on the bonding nature of actinides but could also provide critical information toward the development of nuclear fuel cycle,waste management,and national security.Plutonium(Pu)is the only element in the periodic table that could exist in four oxidation states in aqueous solutions simultaneously.展开更多
The solid solubilities of 207 binary alloys based on the three actinide metals (Th, U and Pu) at room tem- perature are studied with the two theoretical schemes suggested by one of the present authors (ZBW).The re- su...The solid solubilities of 207 binary alloys based on the three actinide metals (Th, U and Pu) at room tem- perature are studied with the two theoretical schemes suggested by one of the present authors (ZBW).The re- sults show that the soluble elements can be distinguished from the insoluble ones by a parabola y_1=a--bx^2 or an ellipse (x_2,-m)~2/c^2+(y_2-n)~2/d^2=l with the total reliabilities of 87.9% and 92.3% respectively for the 207 binary alloys. The contants a and b in the parabola equation, and c, d, m and n in the ellipse equation can be related to some appropriate parameters for each host metal respectively. The reasons are discussed. From the theories the soluble elements in these actinide host metals that have not been measured yet can be predicted in the accuracies of the schemes.展开更多
New evaluations for several actinide nuclei of the third version of Chinese Evaluated Nuclear Data Library for Neutron Reaction Data （CENDL-3.1） have been completed and released. The evaluation is for all neutron in...New evaluations for several actinide nuclei of the third version of Chinese Evaluated Nuclear Data Library for Neutron Reaction Data （CENDL-3.1） have been completed and released. The evaluation is for all neutron induced reactions with uranium, neptunium, plutonium and americium in the mass range A-232-241, 236 239, 236-246 and 240-244, respectively, and cover the incident neutron energy up to 20 MeV. In the present evaluation, much more effort was devoted to improving the reliability of the evaluated nuclear data for available new measured data, especially scarce or absent experimental data. A general description for the evaluation of several actinides＇ data is presented.展开更多
Atomic energy is an important part of current energy resources.Production of nuclear weapons and applications of nuclear fuels in nuclear power plants have accumulated numerous spent fuels containing238U compounds,whi...Atomic energy is an important part of current energy resources.Production of nuclear weapons and applications of nuclear fuels in nuclear power plants have accumulated numerous spent fuels containing238U compounds,which are critical nuclear materials.How to reduce the nuclear wastes and to make use of the spent uranium are key scientific issues of environmental and nuclear science.We have reviewed here the physiochemical properties and photocatalytic mechanisms of homogeneous and heterogeneous uranium-containing materials.The current research efforts demonstrate that spent fuels can become promising new photocatalytic materials.展开更多
In this article,a comprehensive study of the fission process of Th,U,Pu,and Cm isotopes using a Yukawa-folded meanfield plus standard pairing model is presented.The study focused on analyzing the effects of the pairin...In this article,a comprehensive study of the fission process of Th,U,Pu,and Cm isotopes using a Yukawa-folded meanfield plus standard pairing model is presented.The study focused on analyzing the effects of the pairing interaction on the fragment mass distribution and its dependence on nuclear elongation.The significant role of pairing interactions in the fragment mass distributions of^(230)Th,^(234)U,^(240)Pu,and^(246)Cm was demonstrated.Numerical analysis revealed that increasing the pairing interaction strength decreased the asymmetric fragment mass distribution and increased the symmetric distribution.Furthermore,the odd-even mass differences at symmetric and asymmetric fission points were examined,highlighting their sensitivity to changes in the pairing interaction strength.Systematic analysis of the Th,U,Pu,and Cm isotope fragment mass distributions demonstrated the effectiveness of the model in reproducing the experimental data.In addition,the effects of the zero-point energy and half-width parameter on the fragment mass distribution for^(240)Pu were explored.Thus,this study provides valuable insights into the fission process by emphasizing the importance of pairing interactions and their relationship with nuclear elongation.展开更多
基金The calculations were supported by the National Basic Research Program of China （No. 2013CB834603） and National Natural Science Foundation of China （Nos. 91426302, 21590792, and 21433005） and were performed using supercomputers at Tsinghua National Laboratory for Information Science and Technology and the Supercomputing Center, Computer Network Infor- mation Center of the Chinese Academy of Sciences.
文摘Single-atom catalysts are of great interest and importance for designing new high-performance low-cost catalysts. We investigated CO oxidation catalyzed by single gold atoms supported on thoria （Au/ThO2） and doped ThO2 using density functional theory with Hubbard-type on-site Coulomb interaction （DFT ＋ U）. The calculation results show that the Au-doped THO2（111） catalyst exhibits remarkable catalytic activity for CO oxidation via the Eley-Rideal mechanism in three steps, where the rate-determining step is decomposition of the OCOO＋ intermediate with an energy barrier of 0.58 eV. Moreover, our results also reveal a new mechanism of CO oxidation on a gold adatom supported by THO2（111）, where O2 is adsorbed only at the Th site on the surface, and the gas-phase CO then reacts directly with the activated O2＋ to form CO2, which is the rate-limiting step, with a barrier of 0.46 eV. It is found that CO oxidation can occur without CO and O2 coadsorption on Au, which was previously considered a key intermediate. Therefore, these results provide new insights into CO oxidation on isolated gold atoms supported by the 5f-element compound THO2（111）. This mechanism can help clarify the catalytic cycle of CO oxidation, support the design of high- performance low-cost catalysts, and elucidate the redox properties of actinide oxides.
基金Supported by the National Natural Science Foundation of China(12035011,11975167,11761161001,11565010,11961141003,11905103,11947211)the National Key R&D Program of China(2018YFA04044032016YFE0129300)+2 种基金the Science and Technology Development Fund of Macao(008/2017/AFJ)the Fundamental Research Funds for the Central Universities(22120210138)the China Postdoctoral Science Foundation(2019M660095,2020T130478)。
文摘Neutron-deficient actinide nuclei provide a valuable window to probe heavy nuclear systems with large proton-neutron ratios. In recent years, several new neutron-deficient Uranium and Neptunium isotopes have been observed using α-decay spectroscopy [Z. Y. Zhang et al., Phys. Rev. Lett. 122, 192503(2019);L. Ma et al., Phys. Rev.Lett. 125, 032502(2020);Z. Y. Zhang et al., Phys. Rev. Lett. 126, 152502(2021)]. In spite of these achievements,some neutron-deficient key nuclei in this mass region are still unknown in experiments. Machine learning algorithms have been applied successfully in different branches of modern physics. It is interesting to explore their applicability in α-decay studies. In this work, we propose a new model to predict the α-decay energies and half-lives within the framework based on a machine learning algorithm called the Gaussian process. We first calculate the α-decay properties of the new actinide nucleus 214 U. The theoretical results show good agreement with the latest experimental data, which demonstrates the reliability of our model. We further use the model to predict the α-decay properties of some unknown neutron-deficient actinide isotopes and compare the results with traditional models. The results may be useful for future synthesis and identification of these unknown isotopes.
基金Acknowledgements We would like to thank Drs. Jun Liu and Lei Chen for the stimulating discussions. We would also like to acknowledge the support of the National Natural Science Foundation of China （No. 11374004） and the Science and Technology Development Program of Jilin Province of China （No. 20150519021JH）. Z. W. also acknowledges the Fok Ying Tung Education Foundation （No. 142001） and High Performance Computing Center of Jilin University.
文摘Actinide elements encaged in a superatomic cluster can exhibit unique properties due to their hyperactive valence electrons. Herein, the electronic and spectroscopic properties of Th@Au14 are predicted and compared with that of the isoelectronic entities [Ac@Au14]- and [Pa@Au14]＋ using density functional theory. The calculation results indicate that these clusters all adopt a closed- shell superatomic 18-electron configuration of the 1S21p61D10 Jellium state. The absorption spectrum of Th@Au14 can be interpreted by the Jelliumatic orbital model. In addition, calculated spectra of pyridine-Th@Au14 complexes in the blue laser band exhibit strong peaks attributable to charge transfer （CT） from the metal to the pyridine molecule. These charge-transfer bands lead to a resonant surface-enhanced Raman scattering （SERS） enhancement of -104. This work suggests a basis for designing and synthesizing SERS substrate materials based on actinide-embedded gold superatom models.
文摘The complete-fusion reaction^(204)Pb(^(48)Ca,2n)^(250)No was used to study two activities of^(250)No with distinct half-lives.A total of 1357 events were observed in the SFiNx neutron detection system.The average number of neutrons emitted per spontaneous fission of^(250)No was determined to be(4.1±0.1).The unusually symmetrical shape of the prompt neutron multiplicity distribution was restored and presented for the first time.Statistical tests were performed to compare the prompt neutron multiplicity distributions associated with the ground state and K-isomer state decays.
基金support of the National Natural Science Foundation of China(Nos.22076187,22122609)the Hunan Province Natural Science Foundation of China(No.2023JJ40530)+1 种基金the Scientific Research Fund of Hunan Provincial Education Department(No.22C0202)The National Science Fund for Distinguished Young Scholars(No.21925603)。
文摘Four novel compounds based on hexanuclear thorium cluster were synthesized and characterized.Compound 1[Th_(6)(HPy C)_(8)(HCOO)_(4)]is formed by replacing formate ligands of preassembled thorium cluster[Th_(6)O_(4)(OH)_(4)(H_(2)O)_(6)(HCOO)_(12)]with eight H_(2)Py C(4-pyrazolecarboxylic acid)under solvothermal conditions.Each of the HPy C^(-)ligands is coordinated with one Cu^(2+)to form the(4,8)-connected scu-net structure of compound 2[(Cu Cl_(2))_(2)Th_(6)(HPy C)_8(HCOO)_(4)].In compound 3[(Cu Cl_(2))_(2)Th_(6)(HPy C)_(10)(HCOO)_(4)],ten of the formate ligands of preassembled Th_(6)cluster are replaced by HPy C^(-)ligands.Compared with compound 2,the two extra HPy C^(-)ligands in the equatorial plane of the Th_(6)cluster in compound 3 are not further connected to copper ions.Therefore,the topology structure of compound 3 is same with that of compound 2.Compound 4[(Cu_(3)Cl_(2))(Cu Cl_(2))Th_(6)(Py C)_(3)(HPy C)_(4)(HCOO)_(5)]contains three kinds of metal nodes,Th_(6)cluster,Cu_(3)cluster and mononuclear Cu^(2+),and exhibits a novel(5,7)-connected net structure,which was first discovered in actinide MOFs.Furthermore,considering the satisfactory stability of compound 4 and its unsaturated metal nodes and Lewis acid sites,the catalysis of cycloaddition of CO_(2)was further studied.We found that this thorium-copper heterometallic cluster organic framework can be used as a potential actinide functional material for catalyzing the efficient CO_(2)conversion to value-added products.
基金funding support from the Science Challenge Project(TZ2016004)the National Natural Science Foundation of China(21825601,21790374,21806118,and 21727801)+1 种基金The computational work was financially supported by the Foundation of President of China Academy of Engineering Physics(no.YZJJSQ2017072)by the National Natural Science Foundation of China(21590792,21433005,and 21701006).
文摘Crystalline coordination complexes of actinides,especially in atypical oxidation states,are not only fundamentally important for expanding the notably limited knowledge on the bonding nature of actinides but could also provide critical information toward the development of nuclear fuel cycle,waste management,and national security.Plutonium(Pu)is the only element in the periodic table that could exist in four oxidation states in aqueous solutions simultaneously.
文摘The solid solubilities of 207 binary alloys based on the three actinide metals (Th, U and Pu) at room tem- perature are studied with the two theoretical schemes suggested by one of the present authors (ZBW).The re- sults show that the soluble elements can be distinguished from the insoluble ones by a parabola y_1=a--bx^2 or an ellipse (x_2,-m)~2/c^2+(y_2-n)~2/d^2=l with the total reliabilities of 87.9% and 92.3% respectively for the 207 binary alloys. The contants a and b in the parabola equation, and c, d, m and n in the ellipse equation can be related to some appropriate parameters for each host metal respectively. The reasons are discussed. From the theories the soluble elements in these actinide host metals that have not been measured yet can be predicted in the accuracies of the schemes.
文摘New evaluations for several actinide nuclei of the third version of Chinese Evaluated Nuclear Data Library for Neutron Reaction Data （CENDL-3.1） have been completed and released. The evaluation is for all neutron induced reactions with uranium, neptunium, plutonium and americium in the mass range A-232-241, 236 239, 236-246 and 240-244, respectively, and cover the incident neutron energy up to 20 MeV. In the present evaluation, much more effort was devoted to improving the reliability of the evaluated nuclear data for available new measured data, especially scarce or absent experimental data. A general description for the evaluation of several actinides＇ data is presented.
基金supported by the National Basic Research Program of China(973 Project,2011CB932400)Strategic International Collaborative Research Program of China(SICORP,2013DFG50150)
文摘Atomic energy is an important part of current energy resources.Production of nuclear weapons and applications of nuclear fuels in nuclear power plants have accumulated numerous spent fuels containing238U compounds,which are critical nuclear materials.How to reduce the nuclear wastes and to make use of the spent uranium are key scientific issues of environmental and nuclear science.We have reviewed here the physiochemical properties and photocatalytic mechanisms of homogeneous and heterogeneous uranium-containing materials.The current research efforts demonstrate that spent fuels can become promising new photocatalytic materials.
基金This work was supported by the National Natural Science Foundation of China(Nos.12275115 and 12175097)the Educational Department of Liaoning Province(No.LJKMZ20221410).
文摘In this article,a comprehensive study of the fission process of Th,U,Pu,and Cm isotopes using a Yukawa-folded meanfield plus standard pairing model is presented.The study focused on analyzing the effects of the pairing interaction on the fragment mass distribution and its dependence on nuclear elongation.The significant role of pairing interactions in the fragment mass distributions of^(230)Th,^(234)U,^(240)Pu,and^(246)Cm was demonstrated.Numerical analysis revealed that increasing the pairing interaction strength decreased the asymmetric fragment mass distribution and increased the symmetric distribution.Furthermore,the odd-even mass differences at symmetric and asymmetric fission points were examined,highlighting their sensitivity to changes in the pairing interaction strength.Systematic analysis of the Th,U,Pu,and Cm isotope fragment mass distributions demonstrated the effectiveness of the model in reproducing the experimental data.In addition,the effects of the zero-point energy and half-width parameter on the fragment mass distribution for^(240)Pu were explored.Thus,this study provides valuable insights into the fission process by emphasizing the importance of pairing interactions and their relationship with nuclear elongation.
