Hollow TiO₂ porous nanosheets: transformation from ZnO porous nanosheets and application in photoelectrochemical cells

Hierarchical nanostructures of metal oxides for enhancing charge separation and transport in photoelectrochemical solar energy conversion systems

Photoelectrochemical solar energy conversion systems, including photoelectrochemical water splitting and photoelectrochemical solar cells (dye-sensitized solar cells, DSSCs), are under intensive development aiming at efficiently harvesting and utilizing solar energy. Metal oxides carved into hierarchical nanostructures are thought to be promising for improving photoelectrochemical performance by enhancing charge separation and transport. Herein, we review the recent progress in the research on the design and applications of metal oxide hierarchical nanostructures in water splitting and DSSC systems with a view to understanding how they improve the device performance in terms of enhanced charge separation and transport properties. This review will end with a conclusion on metal oxide hierarchical nanostructures together with potential future research directions thereof.

Geometrical implication of ion transporters employing an ellipsoidal hollow structure in pseudo-solid electrolytes

We demonstrate facilitated ion transport in oligomer electrolytes by introducing TiO2 hollow particles of ellipsoidal and spherical shapes. It was found that the TiO2 hollow particles of ellipsoidal shape are much more effective in constructing ionic diffusion paths for the Grotthuss mechanism, resulting in highly enhanced diffusion coefficients of ions such as I(-) and I3(-) in oligomer electrolytes. Compared to the hollow spheres of the TiO2 component, the ellipsoidal hollow particles of the TiO2 component provide 11% larger ionic diffusion coefficients, because of their geometry with a relatively small diffusion resistance. Since the facilitated ion transport can render fast redox reactions at both photo and counter electrodes, the solid state dye-sensitized solar cells employing oligomer electrolytes based on the TiO2 hollow ellipsoids exhibit highly improved photovoltaic performances including highly improved energy-conversion efficiency without destabilizing the cell.

Nanosheet arrays of TiO2 synthesized by one step conversion of ZnO nanosheets: boosting of electron transport rate and application in dye solar cells

TiO₂ replica of ZnO nanosheets were synthesized, showing exceptional e-transport properties in dye solar cells.