Flexible aqueous Ni//Zn batteries have attracted much attention as promising candidates for energy storage in the field of flexible electronics.However,the Ni-based cathodes still face the challenges of poor conductiv...Flexible aqueous Ni//Zn batteries have attracted much attention as promising candidates for energy storage in the field of flexible electronics.However,the Ni-based cathodes still face the challenges of poor conductivity,confined charge/mass transfer,and non-flexibility.In this work,we designed a hollow tubular structure consisting of a conductive silver nanowire (Ag NW) wrapped by active Ni Co layered double hydroxide (LDH),for enhancing the electrical conductivity,improving the charge/mass transfer kinetics,and facilitating the ion penetration.By optimizing the contents of Ni,Co and Ag NW,the Ni_(4)Co LDH@Ag_(1.5)NW composite shows a maximum specific capacity of 115.83 m Ah g^(-1)at 0.1 A g^(-1)measured in a two-electrode system.Highlightingly,the flexible aqueous Ni//Zn battery assembled by Ni_(4)Co LDH@Ag_(1.5)NW interwoven with multi-walled carbon nanotube cathode and Zn foil anode realizes a high power density of 160μW cm^(-2)at the energy density of 23.14μWh cm^(-2),which is superior compared with those of oxide/hydroxide based devices and even higher than those of many carbon-based supercapacitors,showing its promising potentials for flexible energy storage applications.展开更多
The hollow cylinders of TiB-Ti composites with a gradient distribution of Ti phase were synthesized by the combination of traditional slurry spray with centrifugal forming process.The influences of the concentration o...The hollow cylinders of TiB-Ti composites with a gradient distribution of Ti phase were synthesized by the combination of traditional slurry spray with centrifugal forming process.The influences of the concentration of sodium hexametaphosphate(SHMP),the concentration of polyvinyl alcohol(PVA)and solid content(20 vol%-35 vol%)on the rheological properties of the TiB_(2)-Ti composite slurries were investigated.Slurries with low viscosity,weak thixotropy and shear-thinning behaviour were obtained for facilitating the slurry spraying process.The effects of different centrifugal conditions on the migration of components during the forming process were studied.The phase composition and the elements distribution of the prepared samples were characterized by the energy-dispersive X-ray spectrometer.The observations revealed that the samples fabricated at 1500 r/min for 3 min had a significant composition variation.For two-phase systems with small density differences and large particle size variation,centrifugal time was more important than centrifugal speed in forming a continuous gradient structure.展开更多
The conversion of CO_(2) into specific aromatics by modulating the morphology of zeolites is a promising strategy.HZSM-5 zeolite with hollow tubular morphology is reported.The morphology of zeolite was precisely contr...The conversion of CO_(2) into specific aromatics by modulating the morphology of zeolites is a promising strategy.HZSM-5 zeolite with hollow tubular morphology is reported.The morphology of zeolite was precisely controlled,and the acid sites on its outer surface were passivated by steam-assisted crystallization method,so that the zeolite exhibits higher aromatic selectivity than sheet HZSM-5 zeolite and greater p-xylene selectivity than chain HZSM-5 zeolite.The tandem catalyst was formed by combining hollow tubular HZSM-5 zeolites with ZnZrO_(x)metal oxides.The para-selectivity of p-xylene reached 76.2%at reaction temperature of 320℃,pressure of 3.0 MPa,and a flow rate of 2400 mL g^(-1)h^(-1)with an H_(2)/CO_(2) molar ratio of 3/1.Further research indicates that the high selectivity of p-xylene is due to the pore structure of hollow tubular HZSM-5 zeolite,which is conducive to the formation of p-xylene.Moreover,the passivation of the acid site located on the outer surface of zeolite effectively prevents the isomerization of p-xylene.The reaction mechanism of CO_(2) hydrogenation over the tandem catalyst was investigated using in-situ diffuse reflectance Fourier transform infrared spectroscopy and density functional theory.The results showed that the CO_(2) to p-xylene followed a methanol-mediated route over ZnZrO_(x)/hollow tubular HZSM-5 tandem catalysts.In addition,the catalyst showed no significant deactivation in the 100 h stability test.This present study provides an effective strategy for the design of catalysts aimed at selectively preparing aromatics through CO_(2)hydrogenation.展开更多
For pursing high-performance supercapacitors,both of the design strategy and structural characteristic of electrode materials are crucial.Herein,we report the in-situ growth of flexible self-assembled 3D hollow tubula...For pursing high-performance supercapacitors,both of the design strategy and structural characteristic of electrode materials are crucial.Herein,we report the in-situ growth of flexible self-assembled 3D hollow tubular Cu_(2)S nanorods on Cu foam substrate(Cu_(2)S@Cu).The Cu substrate is simultaneously acted as a copper source and a collector,which reduces the contact resistance.Moreover,the highly ordered 3D unique structure increases the redox reactive sites and enhances the ion transmission effectively,resulting in greatly improved electrochemical performance.Based on the Cu_(2)S@Cu electrode,the supercapacitor exhibits high areal capacitance of 1000 mF cm^(-2) at a current density of 2 mA cm^(-2),and great cycle stability,maintaining 96.9% capacitance after 10,000 cycles.Furthermore,the supercapacitor also shows an excellent flexibility with no significant decrease in the twisting or bending state.The capacity retention rates are 99.8% and 86.1%,respectively,and finally recover to 99.3%,confirming its great potential in practical application for portable electronic devices.展开更多
Polymerization is a valid strategy to solve the dissolution issue of organic electrode materials in aprotic electrolytes.However,conventional polymers usually with amorphous structures and morphology’s influence on e...Polymerization is a valid strategy to solve the dissolution issue of organic electrode materials in aprotic electrolytes.However,conventional polymers usually with amorphous structures and morphology’s influence on electrochemistry have rarely been studied.Herein,a hollow tubular poly phenyl pyrene-4,5,9,10-tetraone(T-PPh-PTO)organic cathode material was designed and synthesized based on the concentration-gradient of the precursor(PTO-Br2)and asymmetrical internal diffusion during the reaction.The unique hollow structure endowed T-PPh-PTO with a short Li+diffusion path accompanied by a high diffusion Li+coefficient(D≈10−8 cm^(2)·s^(−1)).Thus,T-PPh-PTO presented a capacitance-dominated redox pseudocapacitance action with an outstanding rate performance(173 mAh·g^(−1)at 2 A·g^(−1))and high cycle stability(capacity retention ratio is 91.7%after 2,000 cycles).Our study leads to further developments in designing unique organic structures for energy storage.展开更多
基金sponsored by the National Natural Science Foundation of China(61804054)the Natural Science Foundation of Shanghai(18ZR1410400)+2 种基金the Shanghai Sailing Program(17YF1403300)the Shanghai Aerospace Science and Technology Innovation Fundation(SISP2018)the Shanghai Aerospace Science and Technology Innovation Fund(SAST2019-067)。
文摘Flexible aqueous Ni//Zn batteries have attracted much attention as promising candidates for energy storage in the field of flexible electronics.However,the Ni-based cathodes still face the challenges of poor conductivity,confined charge/mass transfer,and non-flexibility.In this work,we designed a hollow tubular structure consisting of a conductive silver nanowire (Ag NW) wrapped by active Ni Co layered double hydroxide (LDH),for enhancing the electrical conductivity,improving the charge/mass transfer kinetics,and facilitating the ion penetration.By optimizing the contents of Ni,Co and Ag NW,the Ni_(4)Co LDH@Ag_(1.5)NW composite shows a maximum specific capacity of 115.83 m Ah g^(-1)at 0.1 A g^(-1)measured in a two-electrode system.Highlightingly,the flexible aqueous Ni//Zn battery assembled by Ni_(4)Co LDH@Ag_(1.5)NW interwoven with multi-walled carbon nanotube cathode and Zn foil anode realizes a high power density of 160μW cm^(-2)at the energy density of 23.14μWh cm^(-2),which is superior compared with those of oxide/hydroxide based devices and even higher than those of many carbon-based supercapacitors,showing its promising potentials for flexible energy storage applications.
基金National Natural Science Foundation of China(Nos.51521001,51832003,and 51911530153)。
文摘The hollow cylinders of TiB-Ti composites with a gradient distribution of Ti phase were synthesized by the combination of traditional slurry spray with centrifugal forming process.The influences of the concentration of sodium hexametaphosphate(SHMP),the concentration of polyvinyl alcohol(PVA)and solid content(20 vol%-35 vol%)on the rheological properties of the TiB_(2)-Ti composite slurries were investigated.Slurries with low viscosity,weak thixotropy and shear-thinning behaviour were obtained for facilitating the slurry spraying process.The effects of different centrifugal conditions on the migration of components during the forming process were studied.The phase composition and the elements distribution of the prepared samples were characterized by the energy-dispersive X-ray spectrometer.The observations revealed that the samples fabricated at 1500 r/min for 3 min had a significant composition variation.For two-phase systems with small density differences and large particle size variation,centrifugal time was more important than centrifugal speed in forming a continuous gradient structure.
基金financially supported by the National Natural Science Foundation of China(22268039)the Natural Science Foundation for Distinguished Young Scholars of Gansu Province(23JRRA682)。
文摘The conversion of CO_(2) into specific aromatics by modulating the morphology of zeolites is a promising strategy.HZSM-5 zeolite with hollow tubular morphology is reported.The morphology of zeolite was precisely controlled,and the acid sites on its outer surface were passivated by steam-assisted crystallization method,so that the zeolite exhibits higher aromatic selectivity than sheet HZSM-5 zeolite and greater p-xylene selectivity than chain HZSM-5 zeolite.The tandem catalyst was formed by combining hollow tubular HZSM-5 zeolites with ZnZrO_(x)metal oxides.The para-selectivity of p-xylene reached 76.2%at reaction temperature of 320℃,pressure of 3.0 MPa,and a flow rate of 2400 mL g^(-1)h^(-1)with an H_(2)/CO_(2) molar ratio of 3/1.Further research indicates that the high selectivity of p-xylene is due to the pore structure of hollow tubular HZSM-5 zeolite,which is conducive to the formation of p-xylene.Moreover,the passivation of the acid site located on the outer surface of zeolite effectively prevents the isomerization of p-xylene.The reaction mechanism of CO_(2) hydrogenation over the tandem catalyst was investigated using in-situ diffuse reflectance Fourier transform infrared spectroscopy and density functional theory.The results showed that the CO_(2) to p-xylene followed a methanol-mediated route over ZnZrO_(x)/hollow tubular HZSM-5 tandem catalysts.In addition,the catalyst showed no significant deactivation in the 100 h stability test.This present study provides an effective strategy for the design of catalysts aimed at selectively preparing aromatics through CO_(2)hydrogenation.
基金funded by the National Natural Science Foundation of China(No.51672037,61727818 and 61604031)the subproject of the National Key and Development Program of China(2017YFC0602102)the Department of Science and Technology of Sichuan Province(2019YFH0009).
文摘For pursing high-performance supercapacitors,both of the design strategy and structural characteristic of electrode materials are crucial.Herein,we report the in-situ growth of flexible self-assembled 3D hollow tubular Cu_(2)S nanorods on Cu foam substrate(Cu_(2)S@Cu).The Cu substrate is simultaneously acted as a copper source and a collector,which reduces the contact resistance.Moreover,the highly ordered 3D unique structure increases the redox reactive sites and enhances the ion transmission effectively,resulting in greatly improved electrochemical performance.Based on the Cu_(2)S@Cu electrode,the supercapacitor exhibits high areal capacitance of 1000 mF cm^(-2) at a current density of 2 mA cm^(-2),and great cycle stability,maintaining 96.9% capacitance after 10,000 cycles.Furthermore,the supercapacitor also shows an excellent flexibility with no significant decrease in the twisting or bending state.The capacity retention rates are 99.8% and 86.1%,respectively,and finally recover to 99.3%,confirming its great potential in practical application for portable electronic devices.
基金supported by the National Natural Science Foundation of China(Nos.51771094 and 21835004)the National Key Research and Development(R&D)Program of China(No.2016YFB0901500)+1 种基金the Ministry of Education of China(No.B12015)Tianjin Natural Science Foundation(No.18JCZDJC31500).
文摘Polymerization is a valid strategy to solve the dissolution issue of organic electrode materials in aprotic electrolytes.However,conventional polymers usually with amorphous structures and morphology’s influence on electrochemistry have rarely been studied.Herein,a hollow tubular poly phenyl pyrene-4,5,9,10-tetraone(T-PPh-PTO)organic cathode material was designed and synthesized based on the concentration-gradient of the precursor(PTO-Br2)and asymmetrical internal diffusion during the reaction.The unique hollow structure endowed T-PPh-PTO with a short Li+diffusion path accompanied by a high diffusion Li+coefficient(D≈10−8 cm^(2)·s^(−1)).Thus,T-PPh-PTO presented a capacitance-dominated redox pseudocapacitance action with an outstanding rate performance(173 mAh·g^(−1)at 2 A·g^(−1))and high cycle stability(capacity retention ratio is 91.7%after 2,000 cycles).Our study leads to further developments in designing unique organic structures for energy storage.
