Because of the intensified electrochemical activities,mixed metal oxides as a representative for pseudocapacitive materials play a key role for high performance supercapacitor electrodes.Nevertheless,low ion and elect...Because of the intensified electrochemical activities,mixed metal oxides as a representative for pseudocapacitive materials play a key role for high performance supercapacitor electrodes.Nevertheless,low ion and electron transfer rate and poor cycling performance in the electrode practically restrict further promotion of their electrochemical performance.In order to offset the defect,a novel copper(Cu)foamsupported nickel molybdate nanosheet decorated carbon nanotube wrapped copper oxide nanowire array(NiMoO4 NSs-CNTs-CuO NWAs/Cu foam)flexible electrode is constructed.The as-prepared electrode demonstrates a unique core-shell holey nanostructure with a large active surface area,which can provide a large number of active sites for redox reactions.Besides,the CNTs networks supply improved conductivity,which can hasten electron transport.Through this simple and efficient design method,the spatial distribution of each component in the flexible electrode is more orderly,short and fast electron transport path with low intrinsic resistance.As a result,the NiMoO4 NSs-CNTs-CuO NWAs/Cu foam as an adhesiveless supercapacitor electrode material exhibits excellent ene rgy storage perfo rmance with high specific areal capacitance of 23.40 F cm^(-2)at a current density of 2 mA cm^(-2),which outperforms most of the flexible electrodes re ported recently.The assembled asymmetric supercapacitor demonstrates an energy density up to 96.40 mW h cm^(-3)and a power density up to 0.4 W cm^(-3)under a working voltage window of 1.7 V.In addition,outstanding flexibility of up to 100°bend and good cycling stability with the capacitance retention of 82.53%after 10,000 cycles can be obtained.展开更多
Dear Editors,The coronavirus disease 2019(COVID-19),caused by SARS-CoV-2,broke out in early December 2019 has escalated into a global pandemic(Lai et al.2020).Till the May 20 th 2020,more than 4,700,000 people were in...Dear Editors,The coronavirus disease 2019(COVID-19),caused by SARS-CoV-2,broke out in early December 2019 has escalated into a global pandemic(Lai et al.2020).Till the May 20 th 2020,more than 4,700,000 people were infected and the number is still increasing especially in Europe,North America and Asia(https://covid19.who.int/).展开更多
The magnetic hollow silica spheres (MHSS) with uniform cavity size and shell thickness were prepared by a simple and “green” method using functionalized SiO2 spheres as templates. Magnetic particles (Fe3O4) were dep...The magnetic hollow silica spheres (MHSS) with uniform cavity size and shell thickness were prepared by a simple and “green” method using functionalized SiO2 spheres as templates. Magnetic particles (Fe3O4) were deposited on the SiO2 surface by varying the molar ratio of [Fe2+]/[Fe3+] and the molar concentration of iron salts. The obtained magnetic hollow silica spheres exhibited a super-paramagnetic behavior at room temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder scattering (XRD) were applied to characterize the MHSS. Besides, their unit cell parameters are calculated according to results indexing to XRD, the MHSS sample prepared at 0.10 M iron salts and 2:1 molar ratio of [Fe2+]/[Fe3+] has a largest cell angle (β) of unit cell. Due to large hollow cavity space and super-paramagnetic characteristics, the inner amino-functionalized MHSS could be labeled with radioisotope 99Tcm to study the MHSS’s magnetic targeting distribution in vivo. These results indicate that the MHSS has potential in the magnetic targeted drug delivery system which reduces the damage to normal cells and improves the therapeutic effect of cancer.展开更多
Owing to the increasing demand for tribological brakes for space applications, the development of novel materials and advanced technologies is necessary. This paper presents the design, characterization, and realizati...Owing to the increasing demand for tribological brakes for space applications, the development of novel materials and advanced technologies is necessary. This paper presents the design, characterization, and realization of powder metallurgy processed metal-matrix friction materials intended for the above-mentioned tribological brakes. Selecting appropriate ingredients, which provides an effective way to tailor the properties of the friction material, is evolving as a strategy to meet the design requirements. The tribological behaviors of the friction material are experimentally investigated under different conditions, and special attention is focused on the vacuum tribology. Examinations and analyses of the friction surface and subsurface corroborate the wear mechanism. In addition, the erosion resistances of the friction material are evaluated by exposure tests of ultraviolet irradiation and atomic oxygen. Finally, present and potential space applications of the friction material are also introduced based on experimental studies.展开更多
Due to the enhanced electrochemical activities,mixed metal oxides offer new and fascinating opportunities for high-performance supercapacitor electrodes.However,sluggish ionic and electronic kinetics within the electr...Due to the enhanced electrochemical activities,mixed metal oxides offer new and fascinating opportunities for high-performance supercapacitor electrodes.However,sluggish ionic and electronic kinetics within the electrode fundamentally limit further improvement of their electrochemical performance.To compensate for the deficiency,a flexible electrode(CNTF/Ni-Co-Mn-Mo NS/CNTN)composed of vertically-aligned areolate quaternary metal oxide nanosheets sandwiched between carbon nanotubes(CNTs)is constructed in this study,which demonstrates a unique hierarchical porous structure that can provide three-dimensional transport channels for both ions and electrons.The vertically aligned areolate quaternary metal oxide nanosheets enable increased exposed surface area and paths for ion transport,diffusion and redox reactions,resulting in an evident enhancement in electrochemical activities.Besides,the CNT networks provide improved conductivity,which can accelerate the electron transport.As a result,the flexible supercapacitor based on the CNTF/Ni-Co-Mn-Mo NS/CNTN electrode demonstrates a specific areal capacitance of 3738 m F cm^-2,corresponding to a high energy density of 1.17 m W h cm^-2,which outperforms most of the flexible devices reported recently.Additionally,excellent flexibility of up to 180°bend and superior performance stability of 87.87%capacitance retention after 10,000 charge-discharge cycles can be obtained.This unique design opens up a new way in the development of flexible energy storage devices with high performance.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51673117,51973118,and 21805193)the Science and Technology Innovation Commission of Shenzhen(Nos.JCYJ20170818093832350,JCYJ20170818112409808,JSGG20170824112840518,JCYJ20180507184711069,JCYJ20170818100112531,JCYJ20170817094628397,and JCYJ20180305125319991)+1 种基金the Key-Area Research and Development Program of Guangdong Province(Nos.2019B010929002 and 2019B010941001)the China Postdoctoral Science Foundation(No.2019M650212)。
文摘Because of the intensified electrochemical activities,mixed metal oxides as a representative for pseudocapacitive materials play a key role for high performance supercapacitor electrodes.Nevertheless,low ion and electron transfer rate and poor cycling performance in the electrode practically restrict further promotion of their electrochemical performance.In order to offset the defect,a novel copper(Cu)foamsupported nickel molybdate nanosheet decorated carbon nanotube wrapped copper oxide nanowire array(NiMoO4 NSs-CNTs-CuO NWAs/Cu foam)flexible electrode is constructed.The as-prepared electrode demonstrates a unique core-shell holey nanostructure with a large active surface area,which can provide a large number of active sites for redox reactions.Besides,the CNTs networks supply improved conductivity,which can hasten electron transport.Through this simple and efficient design method,the spatial distribution of each component in the flexible electrode is more orderly,short and fast electron transport path with low intrinsic resistance.As a result,the NiMoO4 NSs-CNTs-CuO NWAs/Cu foam as an adhesiveless supercapacitor electrode material exhibits excellent ene rgy storage perfo rmance with high specific areal capacitance of 23.40 F cm^(-2)at a current density of 2 mA cm^(-2),which outperforms most of the flexible electrodes re ported recently.The assembled asymmetric supercapacitor demonstrates an energy density up to 96.40 mW h cm^(-3)and a power density up to 0.4 W cm^(-3)under a working voltage window of 1.7 V.In addition,outstanding flexibility of up to 100°bend and good cycling stability with the capacitance retention of 82.53%after 10,000 cycles can be obtained.
基金partially supported by the National Natural Science Foundation of China(31702248)。
文摘Dear Editors,The coronavirus disease 2019(COVID-19),caused by SARS-CoV-2,broke out in early December 2019 has escalated into a global pandemic(Lai et al.2020).Till the May 20 th 2020,more than 4,700,000 people were infected and the number is still increasing especially in Europe,North America and Asia(https://covid19.who.int/).
文摘The magnetic hollow silica spheres (MHSS) with uniform cavity size and shell thickness were prepared by a simple and “green” method using functionalized SiO2 spheres as templates. Magnetic particles (Fe3O4) were deposited on the SiO2 surface by varying the molar ratio of [Fe2+]/[Fe3+] and the molar concentration of iron salts. The obtained magnetic hollow silica spheres exhibited a super-paramagnetic behavior at room temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder scattering (XRD) were applied to characterize the MHSS. Besides, their unit cell parameters are calculated according to results indexing to XRD, the MHSS sample prepared at 0.10 M iron salts and 2:1 molar ratio of [Fe2+]/[Fe3+] has a largest cell angle (β) of unit cell. Due to large hollow cavity space and super-paramagnetic characteristics, the inner amino-functionalized MHSS could be labeled with radioisotope 99Tcm to study the MHSS’s magnetic targeting distribution in vivo. These results indicate that the MHSS has potential in the magnetic targeted drug delivery system which reduces the damage to normal cells and improves the therapeutic effect of cancer.
基金the National Natural Science Foundation of China(Nos.51175516 and 51475476)the Fundamental Research Funds for the Central Universities of Central South University(No.2014 zzts023)Shanghai Key Laboratory of Spacecraft Mechanism(No.QT2010-081)of China for their financial supports
文摘Owing to the increasing demand for tribological brakes for space applications, the development of novel materials and advanced technologies is necessary. This paper presents the design, characterization, and realization of powder metallurgy processed metal-matrix friction materials intended for the above-mentioned tribological brakes. Selecting appropriate ingredients, which provides an effective way to tailor the properties of the friction material, is evolving as a strategy to meet the design requirements. The tribological behaviors of the friction material are experimentally investigated under different conditions, and special attention is focused on the vacuum tribology. Examinations and analyses of the friction surface and subsurface corroborate the wear mechanism. In addition, the erosion resistances of the friction material are evaluated by exposure tests of ultraviolet irradiation and atomic oxygen. Finally, present and potential space applications of the friction material are also introduced based on experimental studies.
基金supported by the National Natural Science Foundation of China(51673117 and 21805193)the Science and Technology Innovation Commission of Shenzhen(JSGG20160226201833790,JCYJ20170818093832350,JCYJ20170818112409808 and JSGG20170824112840518)China Postdoctoral Science Foundation(2017M622786,2017M622787 and 2019M653067)。
文摘Due to the enhanced electrochemical activities,mixed metal oxides offer new and fascinating opportunities for high-performance supercapacitor electrodes.However,sluggish ionic and electronic kinetics within the electrode fundamentally limit further improvement of their electrochemical performance.To compensate for the deficiency,a flexible electrode(CNTF/Ni-Co-Mn-Mo NS/CNTN)composed of vertically-aligned areolate quaternary metal oxide nanosheets sandwiched between carbon nanotubes(CNTs)is constructed in this study,which demonstrates a unique hierarchical porous structure that can provide three-dimensional transport channels for both ions and electrons.The vertically aligned areolate quaternary metal oxide nanosheets enable increased exposed surface area and paths for ion transport,diffusion and redox reactions,resulting in an evident enhancement in electrochemical activities.Besides,the CNT networks provide improved conductivity,which can accelerate the electron transport.As a result,the flexible supercapacitor based on the CNTF/Ni-Co-Mn-Mo NS/CNTN electrode demonstrates a specific areal capacitance of 3738 m F cm^-2,corresponding to a high energy density of 1.17 m W h cm^-2,which outperforms most of the flexible devices reported recently.Additionally,excellent flexibility of up to 180°bend and superior performance stability of 87.87%capacitance retention after 10,000 charge-discharge cycles can be obtained.This unique design opens up a new way in the development of flexible energy storage devices with high performance.
