The precursors with NiCO3·2Ni（OH）2·2H2O, Fe2O3·nH2O coated alumina microspheres were prepared by the aqueous heterogeneous precipitation using metal salts, ammonium bicarbonate and α-Al2O3 micropowde...The precursors with NiCO3·2Ni（OH）2·2H2O, Fe2O3·nH2O coated alumina microspheres were prepared by the aqueous heterogeneous precipitation using metal salts, ammonium bicarbonate and α-Al2O3 micropowders as the starting materials. Magnetic metal Ni, α-Fe coated alumina, core-shell structural microspheres were successfully obtained by thermal reduction of the precursors at 700℃ for 2h, respectively. Powders of the precursors and the resultant metal （Ni, α-Fe） coated alumina micropowders were characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The results show that optimized precipitation parameters are concentration of alumina micropowders of 15g/L, rate of adding reactants of 5mL/min and pH value of 7.5. And under the optimized conditions, the spherical precursors without aggregations or agglomerations are obtained, then transferred into Ni, α-Fe coated alumina microspheres by thermal reduction. It is possible to adjust metal coating thicknesses and fabricate a multilayer structured metal/ceramics, core-shell microspherical powder materials.展开更多
A facile colloidal route to synthesize MoSe2 porous microspheres with diameters of 400-600 nm made up of MoSe2 monolayer flakes （-0.7 nm in thickness） is reported. The solvents trioctylamine （TOA） and oleylamine ...A facile colloidal route to synthesize MoSe2 porous microspheres with diameters of 400-600 nm made up of MoSe2 monolayer flakes （-0.7 nm in thickness） is reported. The solvents trioctylamine （TOA） and oleylamine （OAM） are found to play important roles in the formation of MoSe2 microspheres, whereby TOA determines the three-dimensional （3D） microspherical morphology and OAM directs the formation of MoSes monolayer flakes. The robust 3D MoSe2 microspheres exhibit remarkable activity and durability for the electrocatalytic hydrogen evolution reaction （HER） in acid, maintaining a small onset overpotential of -77 mV and keeping a small overpotential of 100 mV for a current density of 5 mA/cm2 after 1,000 cycles. In addition, similar 3D WSe2 microspheres can also be prepared by using this method. We expect this facile colloidal route could further be expanded to synthesize other porous structures which will find applications in fields such as in energy storage, catalysis, and sensing.展开更多
The electrorotation of microspheres coated with conductive surface is a novel and important technology for label-free biosensors. Using the electroless plating approach, the polystyrene microspheres with 15 μm and 25...The electrorotation of microspheres coated with conductive surface is a novel and important technology for label-free biosensors. Using the electroless plating approach, the polystyrene microspheres with 15 μm and 25 μm in diameters were coated with 50 nm gold layer in thickness. The electrorotation experiments on those gold coated polystyrene microspheres (GCPMs) were carried out. The results showed that they rotated in the opposite direction of the electric field in a low frequency range (100-100 kHz), and the maximum rotation speed was higher than that of uncoated microspheres. Based on the theory of traveling wave electroosmosis(TWEO) and induced charge electroosmosis (ICEO), the electrorotation of GCPMs was quantitively analyzed and confirmed by observing the fluid flow around GCPM. The equations describing the electroration speed of GCPMs were proposed, which are consistent with the experiment results.展开更多
Urchin-like SnO2 microspheres have been grown for use as photoanodes in dye-sensitized solar cells （DSSCs）. We observed that a thin layer coating of TiO2 on urchin-like SnO2 microsphere photoanodes greatly enhanced ...Urchin-like SnO2 microspheres have been grown for use as photoanodes in dye-sensitized solar cells （DSSCs）. We observed that a thin layer coating of TiO2 on urchin-like SnO2 microsphere photoanodes greatly enhanced dye loading capability and light scattering ability, and achieved comparable solar cell per- formance even at half the thickness of a typical nanocrystalline TiO2 photoanode. In addition, this photoanode only required attaching -55% of the amount of dye for efficient light harvesting compared to one based on nanocrystalline TiO2. Longer decay of transient photovoltage and higher charge recombination resistance evidenced from electrochemical impedance spectroscopy of the devices based on TiO2 coated urchin-like SnO2 revealed slower recombination rates of electrons as a result of the thin blocking layer of TiO2 coated on urchin- like SnO2. TiO2 coated urchin-like SnO2 showed the highest value （76.1 ms） of electron lifetime （＇r） compared to 2.4 ms for bare urchin-like SnO2 and 14.9 ms for nanocrystalline TiO2. TiO2 coated SnO2 showed greatly enhanced open circuit voltage （Voc）, short-circuit current density （Jsc） and fill factor （FF） leading to a four-fold increase in efficiency increase compared to bare SnO2. Although TiO2 coated urchin-like SnO2 showed slightly lower cell efficiency than nanocrystalline TiO2, it only used a half thickness of photoanode and saved -45% of the amount of dye for efficient light harvesting compared to normal nanocrystalline TiO2.展开更多
Hierarchical tin（Ⅲ） oxide, Sn3O4, nanospheres were synthesized via hydrothermal reaction under strongly acidic ambient conditions. The morphology of Sn3O4 varied with decreasing pH. The prickly SnaO4 nanospheres ch...Hierarchical tin（Ⅲ） oxide, Sn3O4, nanospheres were synthesized via hydrothermal reaction under strongly acidic ambient conditions. The morphology of Sn3O4 varied with decreasing pH. The prickly SnaO4 nanospheres changed into SnaO4 nanospheres covered with single-crystalline nanoplates having a high BET surface area of ca. 55.05 m^2·g^-1 and a band gap of ca. 2.25 eV. Small amounts （0.05 g） of the hierarchical Sn3O4 nanostructures completely decomposed a 30% methyl orange （MO） solution in 100 mL deionized water within 15 min under one sun condition （UV ＋ visible light）. The Sn3O4 photocatalyst exhibited a fast decomposition rate of 1.73 ×10^-1 min^-1, which is a 90.86% enhancement relative to that of the commercially available P25 photocatalyst. The high photocatalytic activity of the hierarchical Sn3O4 nanostructures is attributed to its ability to absorb visible light and its high surface-to-volume ratio.展开更多
A few-layered MoS2-C composite material is studied as a supporting material for silicon nanopowder. Microspheres of the few-layered MoS2-C composite embedded with 30 wt.% Si nanopowder are prepared by one-pot spray py...A few-layered MoS2-C composite material is studied as a supporting material for silicon nanopowder. Microspheres of the few-layered MoS2-C composite embedded with 30 wt.% Si nanopowder are prepared by one-pot spray pyrolysis. The Si nanopowder particles with high capacity are completely surrounded by the few-layered MoS2-C composite matrix. The discharge capacities of the MoS2-C composite microspheres with and without 30 wt.% Si nanopowder after 100 cycles are 1,020 and 718 mAh·g^-1 at a current density of 1,000 mA·g^-1 respectively. The spherical morphology of the MoS2-C composite microspheres embedded with Si nanopowder is preserved even after 100 cycles because of their high structural stability during cycling. The MoS2-C composite layer prevents the formation of unstable solid-electrolyte interface （SEI） layers on the Si nanopowder. Furthermore, as the MoS2-C composite matrix exhibits high capacity and excellent cycling performance, these characteristics are also reflected in the MoS2-C composite microspheres embedded with 30 wt.% Si nanopowder.展开更多
基金supported by the National Natural Science Foundation of China (51172160,50902102)National High Technology Research and Development Program of China (863) (2011AA11A232)~~
文摘The precursors with NiCO3·2Ni（OH）2·2H2O, Fe2O3·nH2O coated alumina microspheres were prepared by the aqueous heterogeneous precipitation using metal salts, ammonium bicarbonate and α-Al2O3 micropowders as the starting materials. Magnetic metal Ni, α-Fe coated alumina, core-shell structural microspheres were successfully obtained by thermal reduction of the precursors at 700℃ for 2h, respectively. Powders of the precursors and the resultant metal （Ni, α-Fe） coated alumina micropowders were characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The results show that optimized precipitation parameters are concentration of alumina micropowders of 15g/L, rate of adding reactants of 5mL/min and pH value of 7.5. And under the optimized conditions, the spherical precursors without aggregations or agglomerations are obtained, then transferred into Ni, α-Fe coated alumina microspheres by thermal reduction. It is possible to adjust metal coating thicknesses and fabricate a multilayer structured metal/ceramics, core-shell microspherical powder materials.
文摘A facile colloidal route to synthesize MoSe2 porous microspheres with diameters of 400-600 nm made up of MoSe2 monolayer flakes （-0.7 nm in thickness） is reported. The solvents trioctylamine （TOA） and oleylamine （OAM） are found to play important roles in the formation of MoSe2 microspheres, whereby TOA determines the three-dimensional （3D） microspherical morphology and OAM directs the formation of MoSes monolayer flakes. The robust 3D MoSe2 microspheres exhibit remarkable activity and durability for the electrocatalytic hydrogen evolution reaction （HER） in acid, maintaining a small onset overpotential of -77 mV and keeping a small overpotential of 100 mV for a current density of 5 mA/cm2 after 1,000 cycles. In addition, similar 3D WSe2 microspheres can also be prepared by using this method. We expect this facile colloidal route could further be expanded to synthesize other porous structures which will find applications in fields such as in energy storage, catalysis, and sensing.
基金supported by the National Natural Science Foundation of China (Grant No. 51075087)the State Key Lab of Fluid Power Transmission and Control of ZheJiang University (Grant No. GZKF-201004)+1 种基金the China Scholarship Council (Grant No. 2009612129)Program for New Century Excellent Talents in University (Grant No. NCET-09-0054)
文摘The electrorotation of microspheres coated with conductive surface is a novel and important technology for label-free biosensors. Using the electroless plating approach, the polystyrene microspheres with 15 μm and 25 μm in diameters were coated with 50 nm gold layer in thickness. The electrorotation experiments on those gold coated polystyrene microspheres (GCPMs) were carried out. The results showed that they rotated in the opposite direction of the electric field in a low frequency range (100-100 kHz), and the maximum rotation speed was higher than that of uncoated microspheres. Based on the theory of traveling wave electroosmosis(TWEO) and induced charge electroosmosis (ICEO), the electrorotation of GCPMs was quantitively analyzed and confirmed by observing the fluid flow around GCPM. The equations describing the electroration speed of GCPMs were proposed, which are consistent with the experiment results.
文摘Urchin-like SnO2 microspheres have been grown for use as photoanodes in dye-sensitized solar cells （DSSCs）. We observed that a thin layer coating of TiO2 on urchin-like SnO2 microsphere photoanodes greatly enhanced dye loading capability and light scattering ability, and achieved comparable solar cell per- formance even at half the thickness of a typical nanocrystalline TiO2 photoanode. In addition, this photoanode only required attaching -55% of the amount of dye for efficient light harvesting compared to one based on nanocrystalline TiO2. Longer decay of transient photovoltage and higher charge recombination resistance evidenced from electrochemical impedance spectroscopy of the devices based on TiO2 coated urchin-like SnO2 revealed slower recombination rates of electrons as a result of the thin blocking layer of TiO2 coated on urchin- like SnO2. TiO2 coated urchin-like SnO2 showed the highest value （76.1 ms） of electron lifetime （＇r） compared to 2.4 ms for bare urchin-like SnO2 and 14.9 ms for nanocrystalline TiO2. TiO2 coated SnO2 showed greatly enhanced open circuit voltage （Voc）, short-circuit current density （Jsc） and fill factor （FF） leading to a four-fold increase in efficiency increase compared to bare SnO2. Although TiO2 coated urchin-like SnO2 showed slightly lower cell efficiency than nanocrystalline TiO2, it only used a half thickness of photoanode and saved -45% of the amount of dye for efficient light harvesting compared to normal nanocrystalline TiO2.
文摘Hierarchical tin（Ⅲ） oxide, Sn3O4, nanospheres were synthesized via hydrothermal reaction under strongly acidic ambient conditions. The morphology of Sn3O4 varied with decreasing pH. The prickly SnaO4 nanospheres changed into SnaO4 nanospheres covered with single-crystalline nanoplates having a high BET surface area of ca. 55.05 m^2·g^-1 and a band gap of ca. 2.25 eV. Small amounts （0.05 g） of the hierarchical Sn3O4 nanostructures completely decomposed a 30% methyl orange （MO） solution in 100 mL deionized water within 15 min under one sun condition （UV ＋ visible light）. The Sn3O4 photocatalyst exhibited a fast decomposition rate of 1.73 ×10^-1 min^-1, which is a 90.86% enhancement relative to that of the commercially available P25 photocatalyst. The high photocatalytic activity of the hierarchical Sn3O4 nanostructures is attributed to its ability to absorb visible light and its high surface-to-volume ratio.
文摘A few-layered MoS2-C composite material is studied as a supporting material for silicon nanopowder. Microspheres of the few-layered MoS2-C composite embedded with 30 wt.% Si nanopowder are prepared by one-pot spray pyrolysis. The Si nanopowder particles with high capacity are completely surrounded by the few-layered MoS2-C composite matrix. The discharge capacities of the MoS2-C composite microspheres with and without 30 wt.% Si nanopowder after 100 cycles are 1,020 and 718 mAh·g^-1 at a current density of 1,000 mA·g^-1 respectively. The spherical morphology of the MoS2-C composite microspheres embedded with Si nanopowder is preserved even after 100 cycles because of their high structural stability during cycling. The MoS2-C composite layer prevents the formation of unstable solid-electrolyte interface （SEI） layers on the Si nanopowder. Furthermore, as the MoS2-C composite matrix exhibits high capacity and excellent cycling performance, these characteristics are also reflected in the MoS2-C composite microspheres embedded with 30 wt.% Si nanopowder.
