Due to their outstanding electrical contact properties,Cd-containing silver-matrix electrical contact materials can meet the requirements of high stability and long life for military defense and aerospace applications...Due to their outstanding electrical contact properties,Cd-containing silver-matrix electrical contact materials can meet the requirements of high stability and long life for military defense and aerospace applications.In order to further reduce the Cd content under the premise of meeting the high-performance requirements,in this study,high-purity intermediate Ti_(2)Cd powder of MAX phase(Ti_(2)CdC)was synthesized with a pressureless technique and then applied to reinforce the Ag matrix.The Cd content of the as-prepared Ag/Ti_(2)Cd composites was actually reduced by 38.31%compared with conventional Ag/CdO material.Based on the systematic study of the effect of heat treatment temperature on the physical phase,morphology,interface and comprehensive physical properties of Ag/Ti_(2)Cd composites,the preferred samples(heat treated at 400°C for 1 h)showed high density(97.77%),low resistivity(2.34μΩ·cm),moderate hardness(90.8HV),high tensile strength(189.9 MPa),and exhibited good electrical contact performance after 40000 cycles of arc discharging under severe conditions(DC 28 V/20 A).The results of microscopic morphological evolution,phase change and elemental distribution of the electrical contact surface show that the combination of high stability of Ti_(2)Cd reinforcing phase,good interfacial bonding with Ag matrix and improved melt pool viscosity in the primary stage of arc erosion,results in low and stable contact resistance(average value 13.20 mΩ)and welding force(average value 0.6 N),low fluctuation of static force(2.2-2.5 N).The decomposition and absorption energy of Ti_(2)Cd and the arc extinguishing effect of Cd vapor are the main reasons for the stable arcing energy and arcing time of electric contacts in the late stage of arc erosion.展开更多
目的建立微波消解-电感耦合等离子体质谱（ICP-MS）直接稀释测定脉络宁注射液中25种矿物质元素（Mg、Ca、Fe、Cu、Zn、Mn、Al、B、Ba、Co、Cr、K、Li、Mo、Na、Ni、P、Pb、Sr、Th、Ti、V、As、Cd和Hg）的方法。方法分别对微波消解条件...目的建立微波消解-电感耦合等离子体质谱（ICP-MS）直接稀释测定脉络宁注射液中25种矿物质元素（Mg、Ca、Fe、Cu、Zn、Mn、Al、B、Ba、Co、Cr、K、Li、Mo、Na、Ni、P、Pb、Sr、Th、Ti、V、As、Cd和Hg）的方法。方法分别对微波消解条件和测试条件进行考察;样品经微波消解后,采用电感耦合质谱仪测定25种矿物质元素,并对测定方法学进行考察。结果确定最佳消解条件为3步缓慢升温：400 W 80℃升温10 min,保留5 min;600 W 120℃升温10 min,保留5 min;900 W 200℃升温20 min,保留20 min;25种矿物质元素在各自的线性范围内线性关系良好,r≥0.999 6,精密度、稳定性和重复性试验的RSD均符合定量分析要求;加标回收率为94.7%~106.1%,RSD在0.34%~2.79%。脉络宁注射液中检测出Mg、Ca、Fe、Cu、Zn、Mn、Al、B、Ba、Co、Cr、K、Li、Mo、Na、Ni、P、Pb、Sr、Th、Ti、V,未检出As、Cd和Hg。结论该方法简便、迅速、准确,适用于脉络宁注射液中25种矿物质元素的同时测定。展开更多
Z-scheme photocatalytic system has been regarded as a popular field of research in photoelectrochemical(PEC)water splitting.Among the many obstacles facing a Z-scheme photocatalytic system,the analysis methods of inte...Z-scheme photocatalytic system has been regarded as a popular field of research in photoelectrochemical(PEC)water splitting.Among the many obstacles facing a Z-scheme photocatalytic system,the analysis methods of interfacial Z-scheme charge transfer still remain a significant challenge.Hence,in this study,CdS/Ti-Fe_(2)O_(3)heterojunction photoanodes are elaborately designed to explore the charge-transfer behavior in PEC water splitting.In this study,photophysical measurements,including the Kelvin probe measurement,surface photovoltage spectroscopy(SPV),and transient photovoltage spectroscopy(TPV),are used to monitor the migration behavior of photogenerated charges at the interface electric field of CdS/Ti-Fe_(2)O_(3)Z-scheme heterojunction photoanodes.The Kelvin probe and SPV measurements demonstrate that CdS/Ti-Fe_(2)O_(3)interfacial driving force favors the rapid transfer of photoexcited electrons to CdS.The double-beam strategy based on TPV indicates that more electrons of Ti-Fe_(2)O_(3)are combined with the holes of CdS owing to the intensive interface electric field.The results of these measurements successfully prove the Z-scheme migration mechanism of CdS/Ti-Fe_(2)O_(3)photoanodes.Benefiting from the desirable charge transfer at the interface electric field,CdS/Ti-Fe_(2)O_(3)photoanodes exhibit superior photocatalytic oxygen evolution reaction performance compared with that of pure Ti-Fe_(2)O_(3).The photocurrent density of the 25CdS/Ti-Fe_(2)O_(3)photoanode reaches 1.94 mA/cm^(2) at 1.23 V versus reversible hydrogen electrode without excess cocatalyst,and it is two times higher than that of pure Ti-Fe_(2)O_(3)photoanode.Therefore,an outstanding strategy is provided in this study to prove the Z-scheme charge-transfer mechanism of photocatalytic systems in PEC water splitting.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(52101064)Jiangsu Planned Projects for Postdoctoral Research Funds(2020Z158)Industry-University-Research Cooperation Projects(RH2000002728,RH2000002332,RH2100000263).
文摘Due to their outstanding electrical contact properties,Cd-containing silver-matrix electrical contact materials can meet the requirements of high stability and long life for military defense and aerospace applications.In order to further reduce the Cd content under the premise of meeting the high-performance requirements,in this study,high-purity intermediate Ti_(2)Cd powder of MAX phase(Ti_(2)CdC)was synthesized with a pressureless technique and then applied to reinforce the Ag matrix.The Cd content of the as-prepared Ag/Ti_(2)Cd composites was actually reduced by 38.31%compared with conventional Ag/CdO material.Based on the systematic study of the effect of heat treatment temperature on the physical phase,morphology,interface and comprehensive physical properties of Ag/Ti_(2)Cd composites,the preferred samples(heat treated at 400°C for 1 h)showed high density(97.77%),low resistivity(2.34μΩ·cm),moderate hardness(90.8HV),high tensile strength(189.9 MPa),and exhibited good electrical contact performance after 40000 cycles of arc discharging under severe conditions(DC 28 V/20 A).The results of microscopic morphological evolution,phase change and elemental distribution of the electrical contact surface show that the combination of high stability of Ti_(2)Cd reinforcing phase,good interfacial bonding with Ag matrix and improved melt pool viscosity in the primary stage of arc erosion,results in low and stable contact resistance(average value 13.20 mΩ)and welding force(average value 0.6 N),low fluctuation of static force(2.2-2.5 N).The decomposition and absorption energy of Ti_(2)Cd and the arc extinguishing effect of Cd vapor are the main reasons for the stable arcing energy and arcing time of electric contacts in the late stage of arc erosion.
文摘目的建立微波消解-电感耦合等离子体质谱（ICP-MS）直接稀释测定脉络宁注射液中25种矿物质元素（Mg、Ca、Fe、Cu、Zn、Mn、Al、B、Ba、Co、Cr、K、Li、Mo、Na、Ni、P、Pb、Sr、Th、Ti、V、As、Cd和Hg）的方法。方法分别对微波消解条件和测试条件进行考察;样品经微波消解后,采用电感耦合质谱仪测定25种矿物质元素,并对测定方法学进行考察。结果确定最佳消解条件为3步缓慢升温：400 W 80℃升温10 min,保留5 min;600 W 120℃升温10 min,保留5 min;900 W 200℃升温20 min,保留20 min;25种矿物质元素在各自的线性范围内线性关系良好,r≥0.999 6,精密度、稳定性和重复性试验的RSD均符合定量分析要求;加标回收率为94.7%~106.1%,RSD在0.34%~2.79%。脉络宁注射液中检测出Mg、Ca、Fe、Cu、Zn、Mn、Al、B、Ba、Co、Cr、K、Li、Mo、Na、Ni、P、Pb、Sr、Th、Ti、V,未检出As、Cd和Hg。结论该方法简便、迅速、准确,适用于脉络宁注射液中25种矿物质元素的同时测定。
文摘Z-scheme photocatalytic system has been regarded as a popular field of research in photoelectrochemical(PEC)water splitting.Among the many obstacles facing a Z-scheme photocatalytic system,the analysis methods of interfacial Z-scheme charge transfer still remain a significant challenge.Hence,in this study,CdS/Ti-Fe_(2)O_(3)heterojunction photoanodes are elaborately designed to explore the charge-transfer behavior in PEC water splitting.In this study,photophysical measurements,including the Kelvin probe measurement,surface photovoltage spectroscopy(SPV),and transient photovoltage spectroscopy(TPV),are used to monitor the migration behavior of photogenerated charges at the interface electric field of CdS/Ti-Fe_(2)O_(3)Z-scheme heterojunction photoanodes.The Kelvin probe and SPV measurements demonstrate that CdS/Ti-Fe_(2)O_(3)interfacial driving force favors the rapid transfer of photoexcited electrons to CdS.The double-beam strategy based on TPV indicates that more electrons of Ti-Fe_(2)O_(3)are combined with the holes of CdS owing to the intensive interface electric field.The results of these measurements successfully prove the Z-scheme migration mechanism of CdS/Ti-Fe_(2)O_(3)photoanodes.Benefiting from the desirable charge transfer at the interface electric field,CdS/Ti-Fe_(2)O_(3)photoanodes exhibit superior photocatalytic oxygen evolution reaction performance compared with that of pure Ti-Fe_(2)O_(3).The photocurrent density of the 25CdS/Ti-Fe_(2)O_(3)photoanode reaches 1.94 mA/cm^(2) at 1.23 V versus reversible hydrogen electrode without excess cocatalyst,and it is two times higher than that of pure Ti-Fe_(2)O_(3)photoanode.Therefore,an outstanding strategy is provided in this study to prove the Z-scheme charge-transfer mechanism of photocatalytic systems in PEC water splitting.
