By using the first-principle calculations and nonequilibrium Green functions method, the electronic transport properties of molecular devices constructed by C82, C80BN and C80N2 were studied. The results show that the...By using the first-principle calculations and nonequilibrium Green functions method, the electronic transport properties of molecular devices constructed by C82, C80BN and C80N2 were studied. The results show that the electronic transport properties of molecular devices are affected by doped atoms. Negative differential resistance (NDR) behavior can be observed in certain bias regions for C82 and C80BN molecular devices but cannot be observed for C80N2 molecular device. A mechanism for the negative differential resistance behavior was suggested.展开更多
By using nonequilibrium Green's function method and first-principles calculations, the electronic transport properties of doped C60 molecular devices were investigated. It is revealed that the C60 molecular devices s...By using nonequilibrium Green's function method and first-principles calculations, the electronic transport properties of doped C60 molecular devices were investigated. It is revealed that the C60 molecular devices show the metal behavior due to the interaction between the C60 molecule and the metal electrode. The current-voltage curve displays a linear behavior at low bias, and the currents have the relation of MI〉M3〉M4〉M2 when the bias voltage is lower than 0.6 V. Electronic transport properties are affected greatly by the doped atoms. Negative differential resistance is found in a certain bias range for C60 and C58BN molecular devices, but cannot be observed in C59B and C59N molecular devices. These unconventional effects can be used to design novel nanoelectronic devices.展开更多
In sequential auctions the phenomenon of declining prices is often observed, which in theory can be represented by a supermartingale. This paper employs the perspective that bidders' values may change over stages ...In sequential auctions the phenomenon of declining prices is often observed, which in theory can be represented by a supermartingale. This paper employs the perspective that bidders' values may change over stages and the common priors are sequentially adjusted by the remaining bidders. It is shown that the declining price sequence can be explained by the adjustment of common priors between auctions. The adjustment of common priors is characterized by stochastic orders. Sufficient and necessary conditions for a supermartingale price sequence are derived.展开更多
Platinum-based material is the most efficient and durable electrocatalyst for motivating the hydrogen evolution reaction(HER)in an acidic electrolyte;however,its low abundance and high cost limit its further applicati...Platinum-based material is the most efficient and durable electrocatalyst for motivating the hydrogen evolution reaction(HER)in an acidic electrolyte;however,its low abundance and high cost limit its further application in proton-exchange membrane water electrolysis(PEMWE)technology.Therefore,minimizing the Pt amount while retaining high activity would be desirable.Herein,we use defect-rich W_(18)O_(49)nanowires to anchor well-dispersed,ultrafine Pt species(Pt-W_(18)O_(49))via a freeze-drying method to avoid aggregation,further mediating an efficient and durable HER in acidic water.Density functional theory analyses also demonstrate that the strong electronic interaction between the Pt species and W_(18)O_(49)support greatly improves the HER performance.With a 1/10 Pt loading amount of the commercial 20 wt%Pt/C,the Pt-W_(18)O_(49)catalyst requires the overpotentials of 116 and 743 mV to achieve high current densities of 100 and 1000 mA cm^(−2)in 0.5 mol L^(−1)H_(2)SO_(4),outperforming those of the 20 wt%Pt/C benchmark.More importantly,the Pt-W_(18)O_(49)catalyst can sustain a high-currentdensity HER at 500 mA cm^(−2)for more than 38 h without obvious degradation.This work paves a new avenue for synergistically reducing the Pt amount and retaining high activity for real-world PEMWE.展开更多
基金Project(50721003)supported by the National Natural Science Foundation of ChinaProject(10C1171)supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProject(11JJ3073)supported by the Natural Science Foundation of Hunan Province,China
文摘By using the first-principle calculations and nonequilibrium Green functions method, the electronic transport properties of molecular devices constructed by C82, C80BN and C80N2 were studied. The results show that the electronic transport properties of molecular devices are affected by doped atoms. Negative differential resistance (NDR) behavior can be observed in certain bias regions for C82 and C80BN molecular devices but cannot be observed for C80N2 molecular device. A mechanism for the negative differential resistance behavior was suggested.
基金Project(07JJ3102) supported by the Natural Science Foundation of Hunan Province, ChinaProject(1343-74236000006) supported by the Graduate Foundation of Hunan Province, ChinaProject(11MY20) supported by the Mittal Entrepreneurship Program of China
文摘By using nonequilibrium Green's function method and first-principles calculations, the electronic transport properties of doped C60 molecular devices were investigated. It is revealed that the C60 molecular devices show the metal behavior due to the interaction between the C60 molecule and the metal electrode. The current-voltage curve displays a linear behavior at low bias, and the currents have the relation of MI〉M3〉M4〉M2 when the bias voltage is lower than 0.6 V. Electronic transport properties are affected greatly by the doped atoms. Negative differential resistance is found in a certain bias range for C60 and C58BN molecular devices, but cannot be observed in C59B and C59N molecular devices. These unconventional effects can be used to design novel nanoelectronic devices.
基金supported by Beijing Higher Education Young Elite Teacher Project(YETP0964)the National Natural Science Foundation of China under Grant Nos.71171053 and 71473282+1 种基金211 Projects FoundationProjects from School of Economics at Central University of Finance and Economics
文摘In sequential auctions the phenomenon of declining prices is often observed, which in theory can be represented by a supermartingale. This paper employs the perspective that bidders' values may change over stages and the common priors are sequentially adjusted by the remaining bidders. It is shown that the declining price sequence can be explained by the adjustment of common priors between auctions. The adjustment of common priors is characterized by stochastic orders. Sufficient and necessary conditions for a supermartingale price sequence are derived.
基金the National Natural Science Foundation of China(21866028)the Development and Innovation Program of Bingtuan(2012QY13)+1 种基金the Program of Science and Technology Innovation Team in Bingtuan(2020CB006)the Achievement Transformation and Technique Popularization Project of Shihezi University(CGZH201910).
文摘Platinum-based material is the most efficient and durable electrocatalyst for motivating the hydrogen evolution reaction(HER)in an acidic electrolyte;however,its low abundance and high cost limit its further application in proton-exchange membrane water electrolysis(PEMWE)technology.Therefore,minimizing the Pt amount while retaining high activity would be desirable.Herein,we use defect-rich W_(18)O_(49)nanowires to anchor well-dispersed,ultrafine Pt species(Pt-W_(18)O_(49))via a freeze-drying method to avoid aggregation,further mediating an efficient and durable HER in acidic water.Density functional theory analyses also demonstrate that the strong electronic interaction between the Pt species and W_(18)O_(49)support greatly improves the HER performance.With a 1/10 Pt loading amount of the commercial 20 wt%Pt/C,the Pt-W_(18)O_(49)catalyst requires the overpotentials of 116 and 743 mV to achieve high current densities of 100 and 1000 mA cm^(−2)in 0.5 mol L^(−1)H_(2)SO_(4),outperforming those of the 20 wt%Pt/C benchmark.More importantly,the Pt-W_(18)O_(49)catalyst can sustain a high-currentdensity HER at 500 mA cm^(−2)for more than 38 h without obvious degradation.This work paves a new avenue for synergistically reducing the Pt amount and retaining high activity for real-world PEMWE.