Although the synthesis of novel nanostructured metal sulfides has been well established,further size-controllable optimization is still valuable to enhance their performance for various applications.Herein,a self-temp...Although the synthesis of novel nanostructured metal sulfides has been well established,further size-controllable optimization is still valuable to enhance their performance for various applications.Herein,a self-template method to size-controllably synthesize the hollow NiCo2S4 nanospheres is reported.Uniformly monodisperse Ni Co precursors with diameter widely ranging from 97 to 550 nm are controllably synthesized and subsequently transformed into hollow NiCo2S4 nanospheres through in situ sulfidation.Smaller nanoparticles’diameter results in the hollow NiCo2S4 nanospheres larger surface area and thinner shell thickness and hence provides much more electrochemical active sites as well as facilitate the ion and electron transfer.Consequently,the hollow NiCo2S4 nanospheres—used as the electrode materials in supercapacitors—achieve 19%enhancement of specific capacity from 484.8 to 575.1 C g-1 through lowering the 42.5%diameter of hollow NiCo2S4 nanospheres from 407 to 234 nm.Moreover,the hollow NiCo2S4 nanospheres with 234 nm diameter exhibit superior rate capacity indicated by 49%capacity retention from 1 to 50 A g-1 and excellent cycling stability(77%after 2000 cycles).Furthermore,this method is a potentially general strategy in the size-controllable synthesis of the metal sulfides hollow nanostructures and results in the remarkable electrochemical applications.展开更多
Nickel nanoparticles （〈10 nm） were success fully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/poly vinylpyrrolidone （PVP） system. The effects of three fac tors, s...Nickel nanoparticles （〈10 nm） were success fully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/poly vinylpyrrolidone （PVP） system. The effects of three fac tors, such as the concentration of the nickel ions, the time of reaction, and the amount of PVP （surfactant）, were discussed. The possible growth process of the particles and optimum reactive conditions was also investigated. The result of transmission electron microscopy （TEM） reveals that these nickel nanoparticles are spherical. The average diameter could be controlled as 25 nm under selected conditions. Highresolution TEM and energydispersive spectroscopy results indicates that the nickel nanoparticles are pure. The UVvisible light absorption spectrum shows that the peaks of nickel nanoparticles moves toward the short wavelength along with the decrease of sizes.展开更多
Monodispersed nitrogen-doped carbon nanospheres with tunable particle size(100-230 nm)were synthesized via self-polymerization of biochemical dopamine in the presence of hexamethylenetetramine as a buffer and F127 as ...Monodispersed nitrogen-doped carbon nanospheres with tunable particle size(100-230 nm)were synthesized via self-polymerization of biochemical dopamine in the presence of hexamethylenetetramine as a buffer and F127 as a size controlling agent.Hexamethylenetetramine can mildly release NH3,which in turn initiates the polymerization reaction of dopamine.The carbon nanospheres obtained exhibited a significant energy storage capability of 265 F·g^(-1)at 0.5 A·g^(-1)and high-rate performance of 82%in 6 mol·L^(-1)KOH(20 A·g^(-1)),which could be attributed to the presence of abundant micromesoporous structure,doped nitrogen functional groups and the small particle size.Moreover,the fabricated symmetric supercapacitor device displayed a high stability of 94%after 5000 cycles,revealing the considerable potential of carbon nanospheres as electrode materials for energy storage.展开更多
Transition metal dichalcogenide nanodots （NDs） have received considerable interest. We report a facile bottom-up synthetic route for MoS2 NDs by using molybdenum pentachloride and L-cysteine as precursors in oleylam...Transition metal dichalcogenide nanodots （NDs） have received considerable interest. We report a facile bottom-up synthetic route for MoS2 NDs by using molybdenum pentachloride and L-cysteine as precursors in oleylamine. The synthesis of NDs with a narrow size distribution ranging from 2.2 to 5.3 nm, was tailored by controlling the reaction time. Because of its coating characteristics, oleyalmine leads to uniformity and monodispersity of the NDs. Moreover, the NDs synthesized have large specific surface areas providing active sites. Graphene possesses outstanding conductivity. Combining the advantages of the two materials, the 0D/2D material exhibits superior electrochemical performance because of the 2D permeable channels for ion adsorption, energy storage, and conversion. The as-prepared MoS2/rGO （-2.2 nm） showed a stable capacity of 220 mAh.g-1 after 10,000 cycles at the current density of 20 A.g-1. Furthermore, a reversible capacity -140 mAh·g-1 was obtained at a much higher current density of 40 A.g-L Additionally, this composite exhibited superior catalytic performance evidenced by a small overpotential （222 mV） to afford 10 mA.cm-2, and a small Tafel slope （59.8 mV-decade-1） with good acid-stability. The facile approach may pave the way for the preparation of NDs with these nanostructures for numerous applications.展开更多
MoS2 has emerged for catalyzing the hydrogen evolution reaction.Various notable strategies have been developed to downsize the MoS2 particles and expose more active edges.However,the restacking issue,which reduces the...MoS2 has emerged for catalyzing the hydrogen evolution reaction.Various notable strategies have been developed to downsize the MoS2 particles and expose more active edges.However,the restacking issue,which reduces the exposure degree,has rarely been taken into account.Herein,we report on a facile proton-induced fast hydrothermal approach to produce size-controllable MoS2 nanocatalysts and demonstrate that along the varying of sheet sizes,there is a trade-off between the intrinsic catalytic activity(mainly determined by the unsaturated sulfur on the sheet edges)and the active edge accessibility(influenced by the assembly structure).The size-optimized catalyst delivers a high performance of a low overpotential of~200 mV at 10 mA/cm^(2),a Tafel slope of 46.3 mV/dec,and a stable working state,which is comparable to the recent notable works.Our findings will provide a pathway for its large-scale application and enhance the water electrolysis performance.展开更多
为改善滤波-x最小均方(filtered-x least mean square,FxLMS)算法在噪声主动控制时无法兼顾收敛速度和稳态误差的问题,提出了基于sigmoid-sinh分段函数的FxLMS(SSFxLMS)算法,并引入蚁狮算法对SFxLMS(sigmoid filtered-x least mean squa...为改善滤波-x最小均方(filtered-x least mean square,FxLMS)算法在噪声主动控制时无法兼顾收敛速度和稳态误差的问题,提出了基于sigmoid-sinh分段函数的FxLMS(SSFxLMS)算法,并引入蚁狮算法对SFxLMS(sigmoid filtered-x least mean square)、ShFxLMS(sinh filtered-x least mean square)、SSFxLMS算法的参数进行优化。分别采用高斯白噪声和实测簇绒地毯织机噪声为输入信号,采用FxLMS、SFxLMS、ShFxLMS、SSFxLMS算法进行噪声主动控制仿真,对比分析这4种算法的性能。结果表明:与其他3种算法相比,采用SSFxLMS算法对高斯白噪声和簇绒地毯织机噪声进行控制时,误差信号的平均绝对值更小,平均降噪量与收敛速度也有大幅度提升。由此可知,SSFxLMS算法有效改善了FxLMS算法无法兼顾收敛速度和稳态误差的问题,研究结果为噪声主动控制算法设计提供了一定的参考。展开更多
基金supported by the National Natural Science Foundation of China(No.51602265)the Special Funding of China Postdoctoral Science Foundation(No.2018T110992)the Sichuan Science and Technology Program(No.2018RZ0074)
文摘Although the synthesis of novel nanostructured metal sulfides has been well established,further size-controllable optimization is still valuable to enhance their performance for various applications.Herein,a self-template method to size-controllably synthesize the hollow NiCo2S4 nanospheres is reported.Uniformly monodisperse Ni Co precursors with diameter widely ranging from 97 to 550 nm are controllably synthesized and subsequently transformed into hollow NiCo2S4 nanospheres through in situ sulfidation.Smaller nanoparticles’diameter results in the hollow NiCo2S4 nanospheres larger surface area and thinner shell thickness and hence provides much more electrochemical active sites as well as facilitate the ion and electron transfer.Consequently,the hollow NiCo2S4 nanospheres—used as the electrode materials in supercapacitors—achieve 19%enhancement of specific capacity from 484.8 to 575.1 C g-1 through lowering the 42.5%diameter of hollow NiCo2S4 nanospheres from 407 to 234 nm.Moreover,the hollow NiCo2S4 nanospheres with 234 nm diameter exhibit superior rate capacity indicated by 49%capacity retention from 1 to 50 A g-1 and excellent cycling stability(77%after 2000 cycles).Furthermore,this method is a potentially general strategy in the size-controllable synthesis of the metal sulfides hollow nanostructures and results in the remarkable electrochemical applications.
基金supported by the National Natural Science Foundation of China(Nos.51272025 and 50872011)the National Key Basic Research Development Plan(973 Program)(No.2007CB613608)the New Century Excellent Researcher Award Program from Ministry of Education of China(No.NCET-08-0732)
文摘Nickel nanoparticles （〈10 nm） were success fully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/poly vinylpyrrolidone （PVP） system. The effects of three fac tors, such as the concentration of the nickel ions, the time of reaction, and the amount of PVP （surfactant）, were discussed. The possible growth process of the particles and optimum reactive conditions was also investigated. The result of transmission electron microscopy （TEM） reveals that these nickel nanoparticles are spherical. The average diameter could be controlled as 25 nm under selected conditions. Highresolution TEM and energydispersive spectroscopy results indicates that the nickel nanoparticles are pure. The UVvisible light absorption spectrum shows that the peaks of nickel nanoparticles moves toward the short wavelength along with the decrease of sizes.
基金the Natural Science Foundation of Shandong Province(Grant No.ZR2019QEM005),Project of Shandong Province Higher Educational Young Innovative Talent Introduction and Cultivation Team[Environment Function Material Innovation Team].
文摘Monodispersed nitrogen-doped carbon nanospheres with tunable particle size(100-230 nm)were synthesized via self-polymerization of biochemical dopamine in the presence of hexamethylenetetramine as a buffer and F127 as a size controlling agent.Hexamethylenetetramine can mildly release NH3,which in turn initiates the polymerization reaction of dopamine.The carbon nanospheres obtained exhibited a significant energy storage capability of 265 F·g^(-1)at 0.5 A·g^(-1)and high-rate performance of 82%in 6 mol·L^(-1)KOH(20 A·g^(-1)),which could be attributed to the presence of abundant micromesoporous structure,doped nitrogen functional groups and the small particle size.Moreover,the fabricated symmetric supercapacitor device displayed a high stability of 94%after 5000 cycles,revealing the considerable potential of carbon nanospheres as electrode materials for energy storage.
基金This work was supported by the National Key R＆D Program （No. 2016YFB0901502）, National NaturalScience Foundation of China （Nos. 51231003, 51271094, and 21231005）, Ministry of Education （Nos. B12015 and IRT13R30）, and the Fundamental Research Funds for the Central Universities.
文摘Transition metal dichalcogenide nanodots （NDs） have received considerable interest. We report a facile bottom-up synthetic route for MoS2 NDs by using molybdenum pentachloride and L-cysteine as precursors in oleylamine. The synthesis of NDs with a narrow size distribution ranging from 2.2 to 5.3 nm, was tailored by controlling the reaction time. Because of its coating characteristics, oleyalmine leads to uniformity and monodispersity of the NDs. Moreover, the NDs synthesized have large specific surface areas providing active sites. Graphene possesses outstanding conductivity. Combining the advantages of the two materials, the 0D/2D material exhibits superior electrochemical performance because of the 2D permeable channels for ion adsorption, energy storage, and conversion. The as-prepared MoS2/rGO （-2.2 nm） showed a stable capacity of 220 mAh.g-1 after 10,000 cycles at the current density of 20 A.g-1. Furthermore, a reversible capacity -140 mAh·g-1 was obtained at a much higher current density of 40 A.g-L Additionally, this composite exhibited superior catalytic performance evidenced by a small overpotential （222 mV） to afford 10 mA.cm-2, and a small Tafel slope （59.8 mV-decade-1） with good acid-stability. The facile approach may pave the way for the preparation of NDs with these nanostructures for numerous applications.
基金supported by the National Natural Science Foundation of China(No.21905206)Shanghai Sail Program(No.19YF1450800)。
文摘MoS2 has emerged for catalyzing the hydrogen evolution reaction.Various notable strategies have been developed to downsize the MoS2 particles and expose more active edges.However,the restacking issue,which reduces the exposure degree,has rarely been taken into account.Herein,we report on a facile proton-induced fast hydrothermal approach to produce size-controllable MoS2 nanocatalysts and demonstrate that along the varying of sheet sizes,there is a trade-off between the intrinsic catalytic activity(mainly determined by the unsaturated sulfur on the sheet edges)and the active edge accessibility(influenced by the assembly structure).The size-optimized catalyst delivers a high performance of a low overpotential of~200 mV at 10 mA/cm^(2),a Tafel slope of 46.3 mV/dec,and a stable working state,which is comparable to the recent notable works.Our findings will provide a pathway for its large-scale application and enhance the water electrolysis performance.
文摘为改善滤波-x最小均方(filtered-x least mean square,FxLMS)算法在噪声主动控制时无法兼顾收敛速度和稳态误差的问题,提出了基于sigmoid-sinh分段函数的FxLMS(SSFxLMS)算法,并引入蚁狮算法对SFxLMS(sigmoid filtered-x least mean square)、ShFxLMS(sinh filtered-x least mean square)、SSFxLMS算法的参数进行优化。分别采用高斯白噪声和实测簇绒地毯织机噪声为输入信号,采用FxLMS、SFxLMS、ShFxLMS、SSFxLMS算法进行噪声主动控制仿真,对比分析这4种算法的性能。结果表明:与其他3种算法相比,采用SSFxLMS算法对高斯白噪声和簇绒地毯织机噪声进行控制时,误差信号的平均绝对值更小,平均降噪量与收敛速度也有大幅度提升。由此可知,SSFxLMS算法有效改善了FxLMS算法无法兼顾收敛速度和稳态误差的问题,研究结果为噪声主动控制算法设计提供了一定的参考。
