Electrochemical properties of Li+ ion insertion in nanoporous TiO2 (anatase) electrodes were studied by voltammetry. Linear and cyclic potential scans were recorded as a function of electrolyte concentration, film thickness, and temperature. The currents were directly proportional to the inner electrode area of the electrodes. The reduction of Ti4+ and oxidation of Ti3+ are sluggish and follows irreversible kinetics. The standard rate constant was (3.5 ± 0.5) × 10-10 cm/s. The transfer coefficient was close to 0.5, indicating that the potential drop appears mainly across the Helmholtz layer. The capacitive currents govern largely the shape of the i − v curves, except within a region near the peak potential where diffusion-limited insertion and extraction of Li+ ions in the anatase lattice are dominating. The diffusion coefficient at 25 °C in the nanoporous structure was approximately 2 × 10-17 cm2/s for insertion and 4 × 10-17 cm2/s for extraction. The activation energy was 0.4 eV for insertion and 0.5 eV for extraction. The maximum obtained mole fraction of Li+ in Li x TiO2 was x = 0.47.

The ability to generate homogeneous particulate thin films of highly oriented and highly porous microparticles of a post transition metal oxide onto polycrystalline and single-crystalline substrates, at low cost, by a template-free, aqueous low-temperature coating process is demonstrated by the fabrication of a large three-dimensional array of perpendicularly oriented hexagonal microtubes of crystalline zincite ZnO from an aqueous solution of zinc nitrate and methenamine.

We are reporting here on the inexpensive fabrication of large three-dimensional and highly oriented porous microrod array of n-type ZnO semiconductor with a unique designed architecture consisting of well-defined, length-tailored, monodisperse, perpendicularly oriented single-crystalline hexagonal rods, grown directly onto polycrystalline, single-crystalline, or amorphous substrates, from an aqueous solution of zinc salt at low temperature.

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Nanostructured NiO film was prepared by depositing nickel hydroxide slurry on conducting glass and sintering at 500 °C to a thickness of about 1 µm. The photocurrent-voltage (IV) characteristics of the plain nanostructured NiO electrode recorded potentiostatically in a standard three-electrode setup upon UV illumination demonstrate p-type behavior, while the IV characteristics of a dye-sensitized nanostructured NiO electrode coated with erythrosin B show cathodic photocurrent under visible light illumination. The highest incident photon-to-current conversion efficiencies of tetrakis(4-carboxyphenyl)porphyrin (TPPC) and erythrosin B-coated NiO films were 0.24% and 3.44%, respectively. In sandwich solar cells with a platinized conducting glass as counter electrode exposed to light from a sun simulator (light intensity: 68 mW/cm 2 ), a short-circuit cathodic photocurrent density (I SC ) of 0.079 mA/cm 2 and an open-circuit voltage (V OC ) of 98.5 mV for TPPC-coated NiO electrode were achieved. Similarly, I SC ) 0.232 mA/cm 2 and V OC ) 82.8 mV were registered when the NiO electrode was coated with erythrosin B. The cathodic photocurrent is explained by hole injection from dye molecule to the valence band of the p-NiO electrode.