Symmetric six oxygen-coordinated Mn structural units(MnO6)in MnO2 with small Mn–O orbital overlap hamper electron transfer rates during energy storage.Herein,we report a novel bond angle modulation strategy to manipu...Symmetric six oxygen-coordinated Mn structural units(MnO6)in MnO2 with small Mn–O orbital overlap hamper electron transfer rates during energy storage.Herein,we report a novel bond angle modulation strategy to manipulate Mn–O orbital overlap in MnO2 through the construction of Mn vacancies(MnO2-VMn),aiming at expediting electron transfer,and thus enhancing energy storage performance.Both experimental and theoretical results disclose that the amplification of Mn–O–Mn bond angles exclusively augments the Mn(dx2-y2)-O(py)orbital overlap and triggers the electron redistribution in MnO2-VMn,inducing an augmented Mn dx2-y2 electron occupation.This heightened presence of active electrons in the Mn dx2-y2 orbital paves the way for accelerating electron transfer and ion transfer in MnO2-VMn.Notably,MnO2-VMn delivers an improved specific capacitance of 425 F g−1 at 1 A g−1 and a superior rate capacity of 265 F g−1 at 20 A g−1.Furthermore,an asymmetric supercapacitor(MnO2-VMn//AC ASC)was fabricated,exhibiting a high energy density of 64.3 Wh kg−1 at a power density of 1000 W kg−1.Furthermore,theoretical insights uncover the profound implications of metal–oxygen–metal bond angle regulation on interatomic orbital overlap modulation.These revelations illuminate pathways for the design of advanced energy storage materials.展开更多
To improve the performance of the K-shortest paths search in intelligent traffic guidance systems, this paper proposes an optimal search algorithm based on the intelligent optimization search theory and the metaphor m...To improve the performance of the K-shortest paths search in intelligent traffic guidance systems, this paper proposes an optimal search algorithm based on the intelligent optimization search theory and the metaphor mechanism of vertebrate immune systems. This algorithm, applied to the urban traffic network model established by the node-expanding method, can expediently realize K-shortest paths search in the urban traffic guidance systems. Because of the immune memory and global parallel search ability from artificial immune systems, K shortest paths can be found without any repeat, which indicates evidently the superiority of the algorithm to the conventional ones. Not only does it perform a better parallelism, the algorithm also prevents premature phenomenon that often occurs in genetic algorithms. Thus, it is especially suitable for real-time requirement of the traffic guidance system and other engineering optimal applications. A case study verifies the efficiency and the practicability of the algorithm aforementioned.展开更多
Porous SnO_2 nanostructures with controlled shapes were synthesized by a facile morphologically conserved transformation from Sn C_2O_4 precursor approach. Well-defined Sn C_2O_4 nanostructures can be obtained through...Porous SnO_2 nanostructures with controlled shapes were synthesized by a facile morphologically conserved transformation from Sn C_2O_4 precursor approach. Well-defined Sn C_2O_4 nanostructures can be obtained through a solution-based precipitation process at ambient conditions without any surfactant. The formation mechanism of such microstructures was tentatively proposed on the basis of intrinsic crystal structure and the reaction conditions. We found that the morphologies of precursor were well maintained while numerous pores were formed during the annealing process. The combined techniques of X-ray diffraction, nitrogen absorption–desorption, field emission scanning electron microscopy, and(high-resolution) transmission electron microscopy were used to characterize the as-prepared SnO_2 products. Moreover, cyclic voltammetry(CV) study shows that the shape of CV presents a current response like roughly rectangular mirror images with respect to the zero-current line without obvious redox peaks, which indicating an ideal capacitive behavior of the SnO_2 electrodes. The photoluminescence(PL) spectrum study suggests that the as-obtained porous SnO_2 nanostructures might have a large number of defects, vacancies of oxygen, and local lattice disorder at the interface, interior and exterior surfaces.展开更多
基金Financial support from the National Natural Science Foundation of China(21575016U20A20154+1 种基金22279005)the National Program for Support of Top-notch Young Professionals。
文摘Symmetric six oxygen-coordinated Mn structural units(MnO6)in MnO2 with small Mn–O orbital overlap hamper electron transfer rates during energy storage.Herein,we report a novel bond angle modulation strategy to manipulate Mn–O orbital overlap in MnO2 through the construction of Mn vacancies(MnO2-VMn),aiming at expediting electron transfer,and thus enhancing energy storage performance.Both experimental and theoretical results disclose that the amplification of Mn–O–Mn bond angles exclusively augments the Mn(dx2-y2)-O(py)orbital overlap and triggers the electron redistribution in MnO2-VMn,inducing an augmented Mn dx2-y2 electron occupation.This heightened presence of active electrons in the Mn dx2-y2 orbital paves the way for accelerating electron transfer and ion transfer in MnO2-VMn.Notably,MnO2-VMn delivers an improved specific capacitance of 425 F g−1 at 1 A g−1 and a superior rate capacity of 265 F g−1 at 20 A g−1.Furthermore,an asymmetric supercapacitor(MnO2-VMn//AC ASC)was fabricated,exhibiting a high energy density of 64.3 Wh kg−1 at a power density of 1000 W kg−1.Furthermore,theoretical insights uncover the profound implications of metal–oxygen–metal bond angle regulation on interatomic orbital overlap modulation.These revelations illuminate pathways for the design of advanced energy storage materials.
基金This work was supported by the Natural Science Foundation of Shandong Province(No.Y2005G12)National Natural ScienceFoundation of China(No.60674062)and the Information Industry Foundation of Shandong Province(No.2006R00046).
文摘To improve the performance of the K-shortest paths search in intelligent traffic guidance systems, this paper proposes an optimal search algorithm based on the intelligent optimization search theory and the metaphor mechanism of vertebrate immune systems. This algorithm, applied to the urban traffic network model established by the node-expanding method, can expediently realize K-shortest paths search in the urban traffic guidance systems. Because of the immune memory and global parallel search ability from artificial immune systems, K shortest paths can be found without any repeat, which indicates evidently the superiority of the algorithm to the conventional ones. Not only does it perform a better parallelism, the algorithm also prevents premature phenomenon that often occurs in genetic algorithms. Thus, it is especially suitable for real-time requirement of the traffic guidance system and other engineering optimal applications. A case study verifies the efficiency and the practicability of the algorithm aforementioned.
基金the financial support of the National Science Foundation for Distinguished Young Scholars of China(Grant No.51025517)the Innovative Group Foundation of NSFC(Grant No.50721062)the financial support of the National 973 project of China(2007CB607606)
文摘Porous SnO_2 nanostructures with controlled shapes were synthesized by a facile morphologically conserved transformation from Sn C_2O_4 precursor approach. Well-defined Sn C_2O_4 nanostructures can be obtained through a solution-based precipitation process at ambient conditions without any surfactant. The formation mechanism of such microstructures was tentatively proposed on the basis of intrinsic crystal structure and the reaction conditions. We found that the morphologies of precursor were well maintained while numerous pores were formed during the annealing process. The combined techniques of X-ray diffraction, nitrogen absorption–desorption, field emission scanning electron microscopy, and(high-resolution) transmission electron microscopy were used to characterize the as-prepared SnO_2 products. Moreover, cyclic voltammetry(CV) study shows that the shape of CV presents a current response like roughly rectangular mirror images with respect to the zero-current line without obvious redox peaks, which indicating an ideal capacitive behavior of the SnO_2 electrodes. The photoluminescence(PL) spectrum study suggests that the as-obtained porous SnO_2 nanostructures might have a large number of defects, vacancies of oxygen, and local lattice disorder at the interface, interior and exterior surfaces.