Various MnO2 nanostructures with controlling phases and morphologies, like α-MnO2 nanorods, nanotubes, nanocubes, nanowires and β-MnO2 cylinder/spindle-like nanosticks have been successfully prepared by hydrothermal...Various MnO2 nanostructures with controlling phases and morphologies, like α-MnO2 nanorods, nanotubes, nanocubes, nanowires and β-MnO2 cylinder/spindle-like nanosticks have been successfully prepared by hydrothermal method, which is simply tuned by changing the ratio of Mn precursor solution to HCl, Mn(Ac)2·4H2O or C6H12O6·H2O, surfactants and reaction temperature and time. The study found out that temperature is a crucial key to get a uniform and surface-smooth nanorod. High ratio of KMnO4 to HCl leads to well dispersed MnO2 nanorods and changing the precursor of HCl into Mn(Ac)2·4H2O or C6H12O6·H2O results in forming nanowires or nanocubes. Different shapes such as cylinder/spindle-like nanosticks could be obtained by adding surfactants. Since the properties rely on the structure of materials firmly, these MnO2 products would be potentially used in supercapacitor and other energy storage applications.展开更多
The microwave-assisted hydrothermal synthesis of Bi 2S 3 na^no^rods was reported. The result showed that microwave irradiation can help to produce Bi 2S 3 nanorods in very short time. There is a negative feedback ...The microwave-assisted hydrothermal synthesis of Bi 2S 3 na^no^rods was reported. The result showed that microwave irradiation can help to produce Bi 2S 3 nanorods in very short time. There is a negative feedback effect which increases the degree of crystallinity in the reaction.展开更多
The hydrothermal synthesis of single-crystallineβ-MnO2 nanorods and their chemical conversion into single-crystalline LiMn2O4 nanorods by a simple solid-state reaction were reported.This method has the advantages of ...The hydrothermal synthesis of single-crystallineβ-MnO2 nanorods and their chemical conversion into single-crystalline LiMn2O4 nanorods by a simple solid-state reaction were reported.This method has the advantages of producing pure,single-phase and crystalline nanorods.The LiMn2O4 nanorods have an diameter of about 300 nm.The discharge capacity and cyclic performance of the batteries were investigated.The LiMn2O4 nanorods show better cyclic performance with a capacity retention ratio of 86.2% after 100 cycles.Battery cyclic studies reveal that the prepared LiMn2O4 nanorods have high capacity with a first discharge capacity of 128.7 mA·h/g.展开更多
Orthorhombic LiMnO_(2)nanoparticles and LiMnO_(2)nanorods have been synthesized by hydrothermal methods.LiMnO_(2)nanoparticles were synthesized by simple one-step hydrothermal method.To obtain rod-like LiMnO_(2),γ-Mn...Orthorhombic LiMnO_(2)nanoparticles and LiMnO_(2)nanorods have been synthesized by hydrothermal methods.LiMnO_(2)nanoparticles were synthesized by simple one-step hydrothermal method.To obtain rod-like LiMnO_(2),γ-MnOOH nanorods were first synthesized and then the H+ions were completely replaced by Li+resulting in LiMnO_(2)nanorods.Their electrochemical performances were thoroughly investigated by galvanostatic tests.Although the LiMnO_(2)nanoparticles have smaller size than LiMnO_(2)nanorods,the latter exhibited higher discharge capacity and better cyclability.For example,the discharge capacities of LiMnO_(2)nanorods reached 200 mA·h/g over many cycles and remained above 180 mA·h/g after 30 cycles.However,the maximum capacity of LiMnO_(2)nanoparticles was only 170 mA·h/g and quickly decreased to 110 mA·h/g after 30 cycles.Nanorods with one-dimensional electronic pathways favor the transport of electrons along the length direction and accommodate volume changes resulting from charge/discharge processes.Thus the morphology of LiMnO_(2)may play an important role in electrochemical performance.展开更多
The in-situ grown of nanostructured MnO2 on activated carbon fiber cloth(ACFC) was obtained with a potassium permanganate solution in the absence of oxidant, reductant or binder addition via a typical microwave hydrot...The in-situ grown of nanostructured MnO2 on activated carbon fiber cloth(ACFC) was obtained with a potassium permanganate solution in the absence of oxidant, reductant or binder addition via a typical microwave hydrothermal synthesis procedure. The carbon fiber cloth serves as a sacrificial reductant and a substrate material to guarantee MnO2 deposition. The results show that the synthesis condition has a great influence on the morphology and structure of MnO2 grown on ACFC.Highly ordered grass-blade-like δ-MnO2/ACFC hybrid nanocomposites were synthesized at 70℃ for 60 min. The grass-blade-like δ-MnO2 are 500 nm in length and 10 nm in depth, and they are well-proportioned grown on the surface of ACFC. The combination of ACFC and MnO2 is rather tight, thus improving the toughness of MnO2. This free-standing, flexible hybrid structure material could be used as a favorable candidate of flexible supercapacitor electrode materials.展开更多
文摘Various MnO2 nanostructures with controlling phases and morphologies, like α-MnO2 nanorods, nanotubes, nanocubes, nanowires and β-MnO2 cylinder/spindle-like nanosticks have been successfully prepared by hydrothermal method, which is simply tuned by changing the ratio of Mn precursor solution to HCl, Mn(Ac)2·4H2O or C6H12O6·H2O, surfactants and reaction temperature and time. The study found out that temperature is a crucial key to get a uniform and surface-smooth nanorod. High ratio of KMnO4 to HCl leads to well dispersed MnO2 nanorods and changing the precursor of HCl into Mn(Ac)2·4H2O or C6H12O6·H2O results in forming nanowires or nanocubes. Different shapes such as cylinder/spindle-like nanosticks could be obtained by adding surfactants. Since the properties rely on the structure of materials firmly, these MnO2 products would be potentially used in supercapacitor and other energy storage applications.
基金ProjectsupportedbytheNaturalScienceFoundationofChina (No .2 97730 0 1)andtheScienceFoundationofAnhuiProvinceEduca tionAdministration (No .2 0 0 2kj115 )
文摘The microwave-assisted hydrothermal synthesis of Bi 2S 3 na^no^rods was reported. The result showed that microwave irradiation can help to produce Bi 2S 3 nanorods in very short time. There is a negative feedback effect which increases the degree of crystallinity in the reaction.
基金Project(2008AA031205)supported by the National High-tech Research and Development Program of China
文摘The hydrothermal synthesis of single-crystallineβ-MnO2 nanorods and their chemical conversion into single-crystalline LiMn2O4 nanorods by a simple solid-state reaction were reported.This method has the advantages of producing pure,single-phase and crystalline nanorods.The LiMn2O4 nanorods have an diameter of about 300 nm.The discharge capacity and cyclic performance of the batteries were investigated.The LiMn2O4 nanorods show better cyclic performance with a capacity retention ratio of 86.2% after 100 cycles.Battery cyclic studies reveal that the prepared LiMn2O4 nanorods have high capacity with a first discharge capacity of 128.7 mA·h/g.
基金the National Natural Science Foundation of China(No.90606006)the State Key Project of Fundamental Research for Nanoscience and Nanotechnology(No.2006CB932300).
文摘Orthorhombic LiMnO_(2)nanoparticles and LiMnO_(2)nanorods have been synthesized by hydrothermal methods.LiMnO_(2)nanoparticles were synthesized by simple one-step hydrothermal method.To obtain rod-like LiMnO_(2),γ-MnOOH nanorods were first synthesized and then the H+ions were completely replaced by Li+resulting in LiMnO_(2)nanorods.Their electrochemical performances were thoroughly investigated by galvanostatic tests.Although the LiMnO_(2)nanoparticles have smaller size than LiMnO_(2)nanorods,the latter exhibited higher discharge capacity and better cyclability.For example,the discharge capacities of LiMnO_(2)nanorods reached 200 mA·h/g over many cycles and remained above 180 mA·h/g after 30 cycles.However,the maximum capacity of LiMnO_(2)nanoparticles was only 170 mA·h/g and quickly decreased to 110 mA·h/g after 30 cycles.Nanorods with one-dimensional electronic pathways favor the transport of electrons along the length direction and accommodate volume changes resulting from charge/discharge processes.Thus the morphology of LiMnO_(2)may play an important role in electrochemical performance.
基金supported by the Natural Science Foundation from Shandong Province of China (ZR2012EMM005)China Scholarship Council
文摘The in-situ grown of nanostructured MnO2 on activated carbon fiber cloth(ACFC) was obtained with a potassium permanganate solution in the absence of oxidant, reductant or binder addition via a typical microwave hydrothermal synthesis procedure. The carbon fiber cloth serves as a sacrificial reductant and a substrate material to guarantee MnO2 deposition. The results show that the synthesis condition has a great influence on the morphology and structure of MnO2 grown on ACFC.Highly ordered grass-blade-like δ-MnO2/ACFC hybrid nanocomposites were synthesized at 70℃ for 60 min. The grass-blade-like δ-MnO2 are 500 nm in length and 10 nm in depth, and they are well-proportioned grown on the surface of ACFC. The combination of ACFC and MnO2 is rather tight, thus improving the toughness of MnO2. This free-standing, flexible hybrid structure material could be used as a favorable candidate of flexible supercapacitor electrode materials.
