Spinel MnCo_(2)O_(4) is a promising energy storage candidate as anode materials in lithium-ion batteries owing to synergistic effects of two intrinsic solid-state redox couples.However,low conductivity,poor rate capac...Spinel MnCo_(2)O_(4) is a promising energy storage candidate as anode materials in lithium-ion batteries owing to synergistic effects of two intrinsic solid-state redox couples.However,low conductivity,poor rate capacity and rapid capacity fading have seriously impaired its practical applications.To overcome the inferiorities,urchin-like MnCo_(2)O_(4)@C core–shell nanowire arrays have been fabricated directly within a porous copper current collector via a facile hydrothermal method followed by a chemical vapor deposition carbonization process.In a typical nanowire,the core is composed of interconnected MnCo_(2)O_(4)nanoparticles and the shell shows as a thin amorphous carbon layer.The integrated MnCo_(2)O_(4)@C/Cu structure could act as working anodes without using additives or polymer binders.While MnCo_(2)O_(4)@C/Cu possesses slightly longer Li-ion insertion/desertion pathway than that of MnCo_(2)O_(4)/Cu,the carbon shell could effectively prevent the pulverization of MnCo_(2)O_(4) and lower down charge transfer resistance and actively participate in Li-ion cycles.The rearrangement of carbon atoms during lithiation/delithiation cycling could inhibit the formation of passive solid electrolyte interphase films.As a result,the MnCo_(2)O_(4)@C/Cu electrode presents superior rate capacity(600 mAh·g^(−1) at 1 A·g^(−1)) and better stability(797 mAh·g^(−1) after 200 cycles at 100 mA·g^(−1)).The excellent reversible Li ion storage capacity,cycling stability and rate capacity endow MnCo_(2)O_(4)@C/Cu great potential as stable and high output integrated anode materials in Li-ion batteries.展开更多
To construct supercapacitors(SCs)with high-efficient electrochemical properties,the morphology and structure of applied electrode materials are the key factors.Herein,three-dimensional(3D)sea urchin-like MnCo_(2)O_(4)...To construct supercapacitors(SCs)with high-efficient electrochemical properties,the morphology and structure of applied electrode materials are the key factors.Herein,three-dimensional(3D)sea urchin-like MnCo_(2)O_(4)nanoarchitectures grown on Ni foam(NF)were successfully synthesized via a simple solvothermal method and subsequent annealing treatment.Electrochemical tests revealed that the area specific capacitances of the MnCo_(2)O_(4)electrode and the corresponding assembled asymmetric device can achieve 1634 and 522 mF·cm^(-2),respectively.When the power density of the assembled asymmetric supercapacitor(ASC)is 2.25 mW·cm^(-2),the maximum energy density can reach 0.163 mW·h·cm^(-2).After 5500 cycles of long-term stability test,the capacity retention rate maintains 91.7%.The excellent electrochemical performance can be mainly ascribed to the unique nanostructure of the material,which provides a great quantity of electroactive sites for Faraday redox reactions as well as accelerates the process of the ions/electrons transport.This work provides a certain reference value for the preparation of MnCo_(2)O_(4)electrode with novel structure and excellent electrochemical performance for SCs.展开更多
MnCo_(2)O_(4) octahedral structure with edge length about 500 nm was successfully synthesized by a simple hydrothermal route.With the use of NaOH,the chemical potential and the rate of ionic motion in the precursor so...MnCo_(2)O_(4) octahedral structure with edge length about 500 nm was successfully synthesized by a simple hydrothermal route.With the use of NaOH,the chemical potential and the rate of ionic motion in the precursor solution were controlled,and the particle size was limited.The magnetization measurements revealed that the products exhibited ferrimagnetic characteristics with different saturation magnetization and coercivity at different measuring temperatures.In addition,the as-prepared MnCo_(2)O_(4) as anodes for lithium-ion batteries(LIBs)exhibited a reversible capacity of 1180 mA·h/g and 1090 mA·h/g at current density of 0.1 C and 1 C,respectively.The excellent cyclic performance was confirmed because the value of reversible capacity for MnCo_(2)O_(4) was 618 mA·h/g after 50 cycles at 0.1 C.Owing to the good rate performance,MnCo_(2)O_(4) octahedral products were suggested to have a promising application as anode material for LIBs.展开更多
Cobalt nickel bimetallic oxides(NiCo_(2)O_(4))have received numerous attentions in terms of their controllable morphology,high temperature,corrosion resistance and strong electromagnetic wave(EMW)absorption capability...Cobalt nickel bimetallic oxides(NiCo_(2)O_(4))have received numerous attentions in terms of their controllable morphology,high temperature,corrosion resistance and strong electromagnetic wave(EMW)absorption capability.However,broadening the absorption bandwidth is still a huge challenge for NiCo_(2)O_(4)-based absorbers.Herein,the unique NiCo_(2)O_(4)@C core-shell microcubes with hollow structures were fabricated via a facile sacrificial template strategy.The concentration of oxygen vacancies and morphologies of the three-dimensional(3D)cubic hollow core-shell NiCo_(2)O_(4)@C framework were effectively optimized by adjusting the calcination temperature.The specially designed 3D framework structure facilitated the multiple reflections of incident electromagnetic waves and provided rich interfaces between multiple components,generating significant interfacial polarization losses.Dipole polarizations induced by oxygen vacancies could further enhance the attenuation ability for the incident EM waves.The optimized NiCo_(2)O_(4)@C hollow microcubes exhibit superior EMW absorption capability with minimum RL(RLmin)of-84.45 dB at 8.4 GHz for the thickness of 3.0 mm.Moreover,ultrabroad effective absorption bandwidth(EAB)as large as 12.48 GHz(5.52-18 GHz)is obtained.This work is believed to illuminate the path to synthesis of high-performance cobalt nickel bimetallic oxides for EMW absorbers with excellent EMW absorption capability,especially in broadening effective absorption bandwidth.展开更多
Direct methanol fuel cell technology recently becomes the focus of both academic and engineering circles,which stimulates the exploitation and utilization of advanced electrode catalysts with high activity and long li...Direct methanol fuel cell technology recently becomes the focus of both academic and engineering circles,which stimulates the exploitation and utilization of advanced electrode catalysts with high activity and long lifespan.Herein,we demonstrate a robust bottom-up approach to the spatial construction of three-dimensional(3D) spinel manganese-cobalt oxide-modified N-doped graphene nanoarchitectures decorated with ultrasmall Pt nanoparticles(Pt/MnCo_(2)O_(4)-NG) via a controllable selfassembly process.The incorporation of MnCo_(2)O_(4)nanocrystals provides abundant hydroxyl sources to promote the oxidative removal of CO-like byproducts on Pt sites,while the existence of 3D porous N-doped graphene networks facilitates the transportation of both ions and electrons in the hybrid system,thus giving rise to remarkable synergetic coupling effects during the methanol oxidation process.Consequently,the optimized Pt/MnCo_(2)O_(4)-NG nano architecture expres ses exceptional electrocatalytic properties with a large electrochemically active surface area of 99.5 m^(2)·g^(-1),a high mass activity of1508.3 mA·mg^(-1),strong toxicity resistance and reliable long-term durability,which have obvious competitive advantages over those of conventional Pt/carbon black,Pt/carbon nano tube,Pt/graphene,and Pt/N-doped graphene catalysts with the same Pt usage.展开更多
基金This study was financially supported by the National Natural Science Foundation of China(No.52072106)the Science and Technology Major Project of Anhui Province(No.202003a05020007)+2 种基金111 Project“New Materials and Technology for Clean Energy”(No.B18018)Fundamental Research Funds for the Central Universities of China(Nos.JZ2019HGBZ0134 and PA2019GDZC0096)the Enterprise Entrusted Project(No.W2021JSKF0868).
文摘Spinel MnCo_(2)O_(4) is a promising energy storage candidate as anode materials in lithium-ion batteries owing to synergistic effects of two intrinsic solid-state redox couples.However,low conductivity,poor rate capacity and rapid capacity fading have seriously impaired its practical applications.To overcome the inferiorities,urchin-like MnCo_(2)O_(4)@C core–shell nanowire arrays have been fabricated directly within a porous copper current collector via a facile hydrothermal method followed by a chemical vapor deposition carbonization process.In a typical nanowire,the core is composed of interconnected MnCo_(2)O_(4)nanoparticles and the shell shows as a thin amorphous carbon layer.The integrated MnCo_(2)O_(4)@C/Cu structure could act as working anodes without using additives or polymer binders.While MnCo_(2)O_(4)@C/Cu possesses slightly longer Li-ion insertion/desertion pathway than that of MnCo_(2)O_(4)/Cu,the carbon shell could effectively prevent the pulverization of MnCo_(2)O_(4) and lower down charge transfer resistance and actively participate in Li-ion cycles.The rearrangement of carbon atoms during lithiation/delithiation cycling could inhibit the formation of passive solid electrolyte interphase films.As a result,the MnCo_(2)O_(4)@C/Cu electrode presents superior rate capacity(600 mAh·g^(−1) at 1 A·g^(−1)) and better stability(797 mAh·g^(−1) after 200 cycles at 100 mA·g^(−1)).The excellent reversible Li ion storage capacity,cycling stability and rate capacity endow MnCo_(2)O_(4)@C/Cu great potential as stable and high output integrated anode materials in Li-ion batteries.
基金the National Natural Science Foundation of China(Grant No.21405105)the Shanghai Natural Science Foundation(14ZR1429300)the State Key Laboratory of Green Catalysis of Sichuan Institutes of Higher Education(LZJ1703).
文摘To construct supercapacitors(SCs)with high-efficient electrochemical properties,the morphology and structure of applied electrode materials are the key factors.Herein,three-dimensional(3D)sea urchin-like MnCo_(2)O_(4)nanoarchitectures grown on Ni foam(NF)were successfully synthesized via a simple solvothermal method and subsequent annealing treatment.Electrochemical tests revealed that the area specific capacitances of the MnCo_(2)O_(4)electrode and the corresponding assembled asymmetric device can achieve 1634 and 522 mF·cm^(-2),respectively.When the power density of the assembled asymmetric supercapacitor(ASC)is 2.25 mW·cm^(-2),the maximum energy density can reach 0.163 mW·h·cm^(-2).After 5500 cycles of long-term stability test,the capacity retention rate maintains 91.7%.The excellent electrochemical performance can be mainly ascribed to the unique nanostructure of the material,which provides a great quantity of electroactive sites for Faraday redox reactions as well as accelerates the process of the ions/electrons transport.This work provides a certain reference value for the preparation of MnCo_(2)O_(4)electrode with novel structure and excellent electrochemical performance for SCs.
基金This work was supported by the Natural Science Foundation of Jilin Province(201215118)and the Special Funds of Changchun University of Technology.
文摘MnCo_(2)O_(4) octahedral structure with edge length about 500 nm was successfully synthesized by a simple hydrothermal route.With the use of NaOH,the chemical potential and the rate of ionic motion in the precursor solution were controlled,and the particle size was limited.The magnetization measurements revealed that the products exhibited ferrimagnetic characteristics with different saturation magnetization and coercivity at different measuring temperatures.In addition,the as-prepared MnCo_(2)O_(4) as anodes for lithium-ion batteries(LIBs)exhibited a reversible capacity of 1180 mA·h/g and 1090 mA·h/g at current density of 0.1 C and 1 C,respectively.The excellent cyclic performance was confirmed because the value of reversible capacity for MnCo_(2)O_(4) was 618 mA·h/g after 50 cycles at 0.1 C.Owing to the good rate performance,MnCo_(2)O_(4) octahedral products were suggested to have a promising application as anode material for LIBs.
基金This work was supported by Natural Science Foundation of Shandong Province(ZR2022ME089)National Natural Science Foundation of China(52207249)Yantai Basic Research Project(2022JCYJ04).
文摘Cobalt nickel bimetallic oxides(NiCo_(2)O_(4))have received numerous attentions in terms of their controllable morphology,high temperature,corrosion resistance and strong electromagnetic wave(EMW)absorption capability.However,broadening the absorption bandwidth is still a huge challenge for NiCo_(2)O_(4)-based absorbers.Herein,the unique NiCo_(2)O_(4)@C core-shell microcubes with hollow structures were fabricated via a facile sacrificial template strategy.The concentration of oxygen vacancies and morphologies of the three-dimensional(3D)cubic hollow core-shell NiCo_(2)O_(4)@C framework were effectively optimized by adjusting the calcination temperature.The specially designed 3D framework structure facilitated the multiple reflections of incident electromagnetic waves and provided rich interfaces between multiple components,generating significant interfacial polarization losses.Dipole polarizations induced by oxygen vacancies could further enhance the attenuation ability for the incident EM waves.The optimized NiCo_(2)O_(4)@C hollow microcubes exhibit superior EMW absorption capability with minimum RL(RLmin)of-84.45 dB at 8.4 GHz for the thickness of 3.0 mm.Moreover,ultrabroad effective absorption bandwidth(EAB)as large as 12.48 GHz(5.52-18 GHz)is obtained.This work is believed to illuminate the path to synthesis of high-performance cobalt nickel bimetallic oxides for EMW absorbers with excellent EMW absorption capability,especially in broadening effective absorption bandwidth.
基金Project(2011M501090) upported by the China Postdoctoral Science FoundationProject(SCUT2012ZZ0042) upported by the Fundamental Research Funds for the Central Universities+1 种基金Project supported by the"SPR-2011"of South China University of TechnologyProject(NRC07/08.EG01)supprted by the Fok Ying Tung Foundation
基金financially supported by the National Natural Science Foundation of China (Nos.22209037 and 51802077)the Fundamental Research Funds for the Central Universities (No.B220202042)。
文摘Direct methanol fuel cell technology recently becomes the focus of both academic and engineering circles,which stimulates the exploitation and utilization of advanced electrode catalysts with high activity and long lifespan.Herein,we demonstrate a robust bottom-up approach to the spatial construction of three-dimensional(3D) spinel manganese-cobalt oxide-modified N-doped graphene nanoarchitectures decorated with ultrasmall Pt nanoparticles(Pt/MnCo_(2)O_(4)-NG) via a controllable selfassembly process.The incorporation of MnCo_(2)O_(4)nanocrystals provides abundant hydroxyl sources to promote the oxidative removal of CO-like byproducts on Pt sites,while the existence of 3D porous N-doped graphene networks facilitates the transportation of both ions and electrons in the hybrid system,thus giving rise to remarkable synergetic coupling effects during the methanol oxidation process.Consequently,the optimized Pt/MnCo_(2)O_(4)-NG nano architecture expres ses exceptional electrocatalytic properties with a large electrochemically active surface area of 99.5 m^(2)·g^(-1),a high mass activity of1508.3 mA·mg^(-1),strong toxicity resistance and reliable long-term durability,which have obvious competitive advantages over those of conventional Pt/carbon black,Pt/carbon nano tube,Pt/graphene,and Pt/N-doped graphene catalysts with the same Pt usage.
