The utilization of rice husk silica as a catalyst: Review and recent progress

Transparent conductive CuFeO2 thin films prepared by sol–gel processing

Building a sulfur host cathode with high electronic transfer ability and strong confinement effect towards intermediate polysulfide is pivotal to develop advanced lithium–sulfur (Li–S) batteries. Herein, a MOF-driven strategy has been employed to synthesize a hierarchical architecture constructed by rooting bismuth oxide nanosheets into Co/N-co-doped porous carbon nanoboxes (Bi2O3@Co/N-PC). After a process of sulfur infiltration, the hierarchical architecture turns into a hybrid composed of sulfur embedded within the Bi2O3@Co/N-PC host (Bi2O3@Co/N-PC@S). When used as the cathode material for Li–S batteries, the as-prepared Bi2O3@Co/N-PC@S not only exhibits a high initial discharge capacity of 1302 mA h g−1 at a current density of 0.25 C, but also maintains a capacity of 732 mA h g−1 after 500 cycles at the current density of 1.5 C. Moreover, the high rate test also demonstrates its exceptional rate capability with a capacity as high as 451 mA h g−1 after 1500 cycles at the current density of 10 C. Such excellent performance can be attributed to the high conductivity and favourable surface structure of the Co/N-doped carbon framework as well as its strong charge coupling with bismuth oxide nanosheets, resulting in low polarization, fast redox reaction kinetics, and high immobilization ability towards intermediate polysulfide.

Rooting bismuth oxide nanosheets into porous carbon nanoboxes as a sulfur immobilizer for lithium–sulfur batteries

Dye-sensitized solar cells are photoelectrochemical devices, which are of great interest due to their ease of fabrication and attractive design. This review details the progress made over the last 20 years into the development of more efficient p-type DSCs with the goal of combining both p and the more widely studied n-type (TiO2)-based photoelectrodes in tandem-DSCs. Such tandem architectures offer an opportunity to collect more light, more efficiently by overcoming the thermodynamic limits of single-junction devices. The main components of the p-DSCs, such as the variety of different sensitizers, p-type semiconductors and electrolytes are introduced and their typical performance in devices are compared. The kinetics of light-induced charge transfer at the interfaces between these materials are also discussed and suggestions are made as to which factors could be a priority for future research to increase the performance of p-type DSC to match state-of-the-art TiO2-based devices, which is necessary for a step change in the conversion efficiency.

/pdf/developing-photocathode-materials-for-p-type-dye-sensitized-1wy8d3uqsh.pdf

Developing photocathode materials for p-type dye-sensitized solar cells

Characterization and optoelectronic properties of sol–gel-derived CuFeO2 thin films

We have prepared CuFeO 2 thin films successfully oriented to the (111) direction on amorphous glass substrates by PLD. The average grain size analyzed by SEM images is about 80–90 nm, and CuFeO 2 grains are formed to the hexagonal flat shape which means CuFeO 2 with the rhombohedral structure was hexagonally grown on the amorphous glass substrate. P-type conductivities are commonly governed by impurities of the amount of metallic Cu phase. However, it was found that the highly (111) oriented CuFeO 2 film shows insulation properties and CuFe 2 O 4 phase affects the change of the type of semiconductor from p-type to n-type.

Impurity dependent semiconductor type of epitaxial CuFeO2 (111) thin films deposited by using a pulsed laser deposition

Cobalt nanoparticles were synthesized by modified thermal decomposition and oxidized in the condition of solution. Crystal structure of fabricated cobalt nanoparticles is determined to be cubic of Fm-3m space group from X-ray diffraction (XRD) measurement. Microstructure of cobalt nanoparticles after the oxidation process show core-shell structure. The particle size and thickness of oxide shell can be controlled by oxidation temperature. The shell thickness of cobalt nanoparticles after the oxidation at 300degC is 4.7 nm, when compared to those oxidized at 250degC with the shell thickness of 2.4 nm due to the change in the oxidation temperature. The magnetic properties of cobalt particles have been measured with VSM. Our results show that cobalt metal (core)/cobalt oxide (shell) has two magnetic behaviors of ferromagnetic and antiferromagnetic properties in magnetic fluid.

Oxidation Effect in Cobalt Nanoparticles Magnetic Fluids

/Si substratesby using pulsed laser deposition (PLD) system. We fabricated three different thin films of BTO, BTO/CNF andCNF/BTO/CNF for magneto-capacitor and studied their crystalline structure, surface and interface morphol-ogy, and magnetic and electrical properties. When three different structures of multilayered thin film werecompared, magnetization of CNF/BTO/CNF thin films was decreased by magnetic and dielectric interaction.Also we confirmed that capacitance of CNF/BTO/CNF multilayered thin film was enhanced as being near tet-ragonal structure with increasing of c/a ratio because of atomic bonding at interface between BTO dielectricand CNF magnetic materials. Finally, we studied the change of the capacitance of CNF/BTO/CNF multilay-ered thin film with magnetic field for emergence of magnetocapacitance and suggested a possibility of enhancedcapacitance.Keywords : magnetocapacitance, multilayer thin film, pulsed laser deposition, interface effect

http://koreascience.or.kr:80/article/JAKO201220962915847.pdf

Jong Soo Hong

Papers

Impurity dependent semiconductor type of epitaxial CuFeO2 (111) thin films deposited by using a pulsed laser deposition

Oxidation Effect in Cobalt Nanoparticles Magnetic Fluids

Possibility of Magnetocapacitor for Multilayered Thin Films