SnO2 hollow nanospheres were successfully synthesized via a facile one-step solvothermal method.Characterizations show that the as-prepared SnO2 spheres are of hollow structure with a diameter at around 50 nm,and especially,the shell of the spheres is assembled by single layer SnO2 nanocrystals.The surface area of the material reaches up to 202.5 m^2/g.As an anode material for Li ion batteries,the sample exhibited improved electrochemical performance compared with commercial SnO2 particles.After cycled at high current rate of 0.5 C,1 C and 0.5 C for 20 cycles,respectively,the electrode can maintain a capacity of 509 mAh/g.The suitable shell thickness/diameter ratio endows the good structural stability of the material during cycling,which promises the excellent cycling performance of the electrode.The large surface area and the ultra thin shell ensure the high rate performance of the material.
The Co3O4 nanowires have been successfully synthesized via modified template method.The as-prepared products have been characterized by EDS,TEM and HRTEM analysis.The magnetic behavior of it is investigated by a magnetic property measurement system.The nanowires exhibit some novel magnetic properties,which are different from its bulk material.The temperature dependence curves of magnetization in zero-field-cooling and field-cooling exhibit two peaks of antiferromagnetic at blocking temperature of～23 K and～31 K,respectively.The field dependent M（H） curves of the Co_3O_4 nanowires at T = 5 and 300 K both exhibit PM properties.Moreover,the diameter of nanowires is hence determined according to the finite size effect as approximately 7-11 nm,in consistent with the characterizations by HRTEM.
Mai Xia MaWei Meng ChenLin GuoJing Hong LiChin Ping ChenShi He Yang
NiO/Co3O4 composite nanosheets have been synthesized via a facile method at low temperature for the first time.The as prepared materials were characterized by X-ray powder diffraction(XRD) and transmission electron microscopy(TEM),and the performance of Li-ion batteries(LIBs) as anode materials were also studied.By controlling the atom ratio of Ni:Co,not only the size of the nanosheets can be controlled,the electrode's conductivity and stability could also be greatly improved.The composite material showed a stable capacity retention during cycling(87% of the second capacity was retained after 15 cycles) even at a relatively large current rate(400 mA/g).The NiO/Co3O4 nanosheet might be promising candidate anode materials in high performance Li-ion batteries.
The porous Co3O4 nanowires have been successfully synthesized via modified template method. A possible growth mechanism governing the formation of such 1D nanowires is proposed. The as-prepared products have been characterized by X-ray Powder Diffraction (XRD), Extended X-ray Absorption Fine-structure (EXAFS), High-resolution Transmission Electron Microscopy (HRTEM) and N2 adsorption/desorption analysis. Our systematic studies have revealed that the porous Co3O4 nanowires show excellent gas sensing performances, which demonstrate the potential application of the 1D nanostructured Co3O4 in the detection of the ethanol gas as a sensor material. The improved performances are owing to its large specific surface area and porous morphology.
MA MaiXiaPAN ZhiYunGUO LinLI JingHongWU ZiYuYANG ShiHe
Single-crystalline Li-doped Co3O4 truncated octahedra with different doping contents were synthesized by a simple combustion method with the fuel of multi-walled carbon nanotubes(MWCNTs).Controlled experiments showed that the pristine well-defined Co3O4 octahedra were obtained with exposed surfaces of {111} planes without lithium doping.In comparison with the octahedra,the truncated Co3O4 octahedra were composed of original {111} planes and extra {100} planes.It could be attributable to the selective adsorption of lithium ions on the {100} planes,making these planes with higher surface energy coexist with the crystal faces of {111}.Furthermore,the Li-doped truncated octahedra and undoped octahedra were used as catalysts in CO oxidation and as anode materials for Li-ion batteries(LIBs).The measurements exhibited that the Li-doped octahedra with added {100} crystal faces showed improved catalytic activity and electrochemical property because of the exposure of the higher energy faces of {100} and enhanced conductivity by Li doping.
