Sainan Yang

Facile preparation of transition metal oxide–metal composites with unique nanostructures and their electrochemical performance as energy storage material

In this work, a facile method for the preparation of a series of transition metal oxide–metal nanocomposites (MO–M) (such as NiO–Ni, Co3O4–Co, Fe3O4–Fe and MnO2–Mn) anchored on conductive nanowire arrays (such as TiC–C core–shell nanowires grown on a Ti alloy sheet) is reported for the first time. The obtained composites possess a unique three-dimensional nanostructure and high electronic conductivity. They have diverse applications as electrodes of energy storage devices. High capacitance and high rate capability have been demonstrated using the NiO–Ni@C@TiC nanocomposite as a model electrode, which shows a specific capacitance as high as 1845 F g−1 at a charge–discharge current density of 5 A g−1 and 811.1 F g−1 after cycling 500 times at an extremely high charge–discharge rate of 100 A g−1.

FeOOH electrodeposited on Ag decorated ZnO nanorods for electrochemical energy storage

In this work, an FeOOH/Ag/ZnO shell/core array electrode was prepared by electro-depositing FeOOH on Ag decorated ZnO nanorod arrays. Some characterization methods, including X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy were used to study the structure and surface morphologies of FeOOH/Ag/ZnO. The results suggest that Ag particles are homogeneously distributed on ZnO nanorods, and FeOOH is well-distributed on the surface of Ag/ZnO nanorod arrays. When evaluated as a supercapacitor electrode material, the FeOOH/Ag/ZnO shell/core array electrode exhibits a high specific capacitance of 376.6 F g−1 at a charge/discharge current density of 1 A g−1, and 70.3% specific capacitance is retained after 1000 cycles. The superior pseudo-capacitive properties of FeOOH/Ag/ZnO shell/core arrays are attributed to the unique shell/core structure. First, the ZnO nanorod arrays as skeleton loading active materials can provide a large surface to volume for easy access of electrolyte ions. Second, the Ag decorated on ZnO nanorods can improve the electrical conductivity of the as-prepared electrode, which can provide fast electron transfer for faradaic reactions. The results confirm that FeOOH/Ag/ZnO shell/core arrays are advantageous as electrochemical energy storage materials.

Reduced graphene oxide decorated on MnO2 nanoflakes grown on C/TiO2 nanowire arrays for electrochemical energy storage

In this work, RGO is decorated on MnO2 nanoflakes, which are electrochemically deposited on preformed C/TiO2 shell/core nanowire arrays to form a RGO/MnO2/C/TiO2 shell/core array electrode. Their structure and surface morphology are studied using X-ray diffraction analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman microscopy, scanning electron microscopy and transmission electron microscopy. The results suggest that a RGO layer was coated on the MnO2 nanoflakes, and the MnO2 nanoflakes have a well-distributed coverage on the surface of the C/TiO2 shell/core nanowire arrays. The RGO/MnO2/C/TiO2 shell/core arrays are evaluated as a supercapacitor electrode material, which exhibits a high specific capacitance of 822.3 F g−1 at a charge/discharge current density of 1 A g−1 and 87.4% specific capacitance retention after 5000 cycles. The superior pseudo-capacitive properties may be due to the unique shell/core structure and the decoration of RGO. The RGO decorated on MnO2 can provide partial double-layer capacitance; on the other hand, the RGO can improve the electrical conductivity of the electrode and alleviate the volume change of MnO2 during charge/discharge processes given its mechanical flexibility. Our results show that the RGO/MnO2/C/TiO2 electrode can be regarded as advantageous for electrochemical energy applications.