This study proposes a method for^(99)Mo production via electron accelerator irradiation of a natural-uranium-bearing liquid molten salt target,with advantages including low nuclear proliferation risk,online extraction...This study proposes a method for^(99)Mo production via electron accelerator irradiation of a natural-uranium-bearing liquid molten salt target,with advantages including low nuclear proliferation risk,online extraction capability,and low construction costs.The approach primarily produces^(99)Mo through photofission of uranium(~95%),specifically^(238)U(γ,f).Secondary neutrons,originating from photonuclear interactions or fission processes,contribute minimally(~5%)to^(99)Mo production owing to their high energies and low fission cross sections.Key parameter analyses revealed that fluoride salt systems exhibit higher^(99)Mo yield.Their performance stems from high bremsstrahlung energy loss rate and superior photon yield,making them optimal molten salt target materials.To maximize photofission and photoneutron cross sections while minimizing highenergy gamma ray shielding requirements,an electron beam energy range of 40-80 MeV is recommended.To suppress local hot spots and prevent molten salt boiling,flow conditions were introduced to enhance convective heat transfer,effectively reducing the peak temperature.At a flow velocity of 0.5 m/s and under 80 MeV energy conditions,the maximum system temperature is only 808.9 K,which is significantly lower than the boiling point of 1773 K.Under optimized parameters,the maximum annual production capacity of~(99)Mo reaches 4486.49 Ci,sufficient for millions of diagnostic procedures and equivalent to 16.37% of China's projected demand for 2030.This method provides a viable pathway for stable,large-scale^(99)Mo production.展开更多
In sodium-ion hybrid capacitors(SIHCs),the high-capacity metal selenide anodes are severely limited by structural instability and polyselenide dissolution/shuttle during cycling.This study proposes an innovative strat...In sodium-ion hybrid capacitors(SIHCs),the high-capacity metal selenide anodes are severely limited by structural instability and polyselenide dissolution/shuttle during cycling.This study proposes an innovative strategy utilizing high-electronegativity N(χ=3.04)to modulate local electronic domains and stabilize amorphous Mo–Se coordination(N/Mo-Se).Through self-polymerization and tunable selenization,N-doped carbon(NC)nanospheres encapsulating N-stabilized amorphous Mo-Se clusters(N/Mo-Se@NC)are successfully constructed.Theoretical and experimental analyses reveal that N-optimization effectively reconstructs the electronic distribution of Mo–Se coordination via strong covalent Mo–N bonds.This significantly enhances the covalency of Mo-Se clusters and induces localized electronic domains,thereby substantially suppressing polyselenide dissolution/shuttle during cycling.Concurrently,the amorphous N/Mo-Se clusters provide isotropic ion diffusion pathways,and together with the threedimensional(3D)conductive networks of the NC,they jointly optimize charge transfer kinetics.The N/Mo-Se@NC anode exhibits a high reversible capacity of 328.7 mAh g^(-1)after 5000 cycles,even at 10.0 A g^(-1),with a remarkable capacity retention of 110%.The assembled N/Mo-Se@NC//AC SIHCs achieve high energy/power densities(236.1 Wh kg^(-1)/9990 W kg^(-1)),demonstrating superior comprehensive performance compared to most previously reported anodes.This study,through high-electronegativity atom modulation and amorphization engineering,opens new avenues for designing highly stable and high-rate Na^(+) storage materials.展开更多
激光粉末床熔融(Laser Powder Bed Fusion,LPBF)技术是定制化多孔纯Mo结构的重要技术。然而,LPBF成形纯Mo试样仍面临表面粗糙度值高及耐蚀性差等问题。电化学抛光(Electrochemical Polishing,ECP)是LPBF成形纯Mo的主要环保型后处理工艺...激光粉末床熔融(Laser Powder Bed Fusion,LPBF)技术是定制化多孔纯Mo结构的重要技术。然而,LPBF成形纯Mo试样仍面临表面粗糙度值高及耐蚀性差等问题。电化学抛光(Electrochemical Polishing,ECP)是LPBF成形纯Mo的主要环保型后处理工艺。研究了不同ECP抛光状态对LPBF成形纯Mo的表面粗糙度及降解特性的影响。结果表明:经电化学抛光处理后,试样表面粗糙度由4.55μm显著降低至1.05μm;相比原始态试样,抛光后试样腐蚀电流密度降低了78.4%。失重率从大到小顺序为:原始态>半抛光>抛光,且随着浸泡时间增加,失重率逐渐增加。溶液pH值波动≤0.5,验证了降解过程未引发局部酸化,符合生物医用材料要求。通过采用ECP处理Mo基材料表面,为合理调控其植入体的降解行为及降解速率的均匀性提供了重要理论依据。展开更多
基金supported by the National Natural Science Foundation of China(Nos.12435012,12175300,and 12475185)Shanghai Natural Science Foundation(No.24ZR1478500)Nuclear energy development project(HNKF202210(24))。
文摘This study proposes a method for^(99)Mo production via electron accelerator irradiation of a natural-uranium-bearing liquid molten salt target,with advantages including low nuclear proliferation risk,online extraction capability,and low construction costs.The approach primarily produces^(99)Mo through photofission of uranium(~95%),specifically^(238)U(γ,f).Secondary neutrons,originating from photonuclear interactions or fission processes,contribute minimally(~5%)to^(99)Mo production owing to their high energies and low fission cross sections.Key parameter analyses revealed that fluoride salt systems exhibit higher^(99)Mo yield.Their performance stems from high bremsstrahlung energy loss rate and superior photon yield,making them optimal molten salt target materials.To maximize photofission and photoneutron cross sections while minimizing highenergy gamma ray shielding requirements,an electron beam energy range of 40-80 MeV is recommended.To suppress local hot spots and prevent molten salt boiling,flow conditions were introduced to enhance convective heat transfer,effectively reducing the peak temperature.At a flow velocity of 0.5 m/s and under 80 MeV energy conditions,the maximum system temperature is only 808.9 K,which is significantly lower than the boiling point of 1773 K.Under optimized parameters,the maximum annual production capacity of~(99)Mo reaches 4486.49 Ci,sufficient for millions of diagnostic procedures and equivalent to 16.37% of China's projected demand for 2030.This method provides a viable pathway for stable,large-scale^(99)Mo production.
基金supported by the National Natural Science Foundation of China(Grant No.52573299)the Natural Science Foundation of Jiangxi province(Grant Nos.20242BAB25223,20232BCJ23025,20232BCJ25040,and 20232BAB214024)the Special Funding Program for Graduate Student Innovation of Jiangxi Province(No.YC2024-S594)。
文摘In sodium-ion hybrid capacitors(SIHCs),the high-capacity metal selenide anodes are severely limited by structural instability and polyselenide dissolution/shuttle during cycling.This study proposes an innovative strategy utilizing high-electronegativity N(χ=3.04)to modulate local electronic domains and stabilize amorphous Mo–Se coordination(N/Mo-Se).Through self-polymerization and tunable selenization,N-doped carbon(NC)nanospheres encapsulating N-stabilized amorphous Mo-Se clusters(N/Mo-Se@NC)are successfully constructed.Theoretical and experimental analyses reveal that N-optimization effectively reconstructs the electronic distribution of Mo–Se coordination via strong covalent Mo–N bonds.This significantly enhances the covalency of Mo-Se clusters and induces localized electronic domains,thereby substantially suppressing polyselenide dissolution/shuttle during cycling.Concurrently,the amorphous N/Mo-Se clusters provide isotropic ion diffusion pathways,and together with the threedimensional(3D)conductive networks of the NC,they jointly optimize charge transfer kinetics.The N/Mo-Se@NC anode exhibits a high reversible capacity of 328.7 mAh g^(-1)after 5000 cycles,even at 10.0 A g^(-1),with a remarkable capacity retention of 110%.The assembled N/Mo-Se@NC//AC SIHCs achieve high energy/power densities(236.1 Wh kg^(-1)/9990 W kg^(-1)),demonstrating superior comprehensive performance compared to most previously reported anodes.This study,through high-electronegativity atom modulation and amorphization engineering,opens new avenues for designing highly stable and high-rate Na^(+) storage materials.
文摘激光粉末床熔融(Laser Powder Bed Fusion,LPBF)技术是定制化多孔纯Mo结构的重要技术。然而,LPBF成形纯Mo试样仍面临表面粗糙度值高及耐蚀性差等问题。电化学抛光(Electrochemical Polishing,ECP)是LPBF成形纯Mo的主要环保型后处理工艺。研究了不同ECP抛光状态对LPBF成形纯Mo的表面粗糙度及降解特性的影响。结果表明:经电化学抛光处理后,试样表面粗糙度由4.55μm显著降低至1.05μm;相比原始态试样,抛光后试样腐蚀电流密度降低了78.4%。失重率从大到小顺序为:原始态>半抛光>抛光,且随着浸泡时间增加,失重率逐渐增加。溶液pH值波动≤0.5,验证了降解过程未引发局部酸化,符合生物医用材料要求。通过采用ECP处理Mo基材料表面,为合理调控其植入体的降解行为及降解速率的均匀性提供了重要理论依据。
