Hierarchically structured AgO films with nano-porosity for photocatalyst and all solid-state thin film battery

Hierarchically structured porous films are urgently needed in the development of some practical devices. In this work, we report an effective way for fabrication of hierarchically porous AgO films by oxidizing Ag films in the environment offered by reactive magnetron sputtering deposition of NiO. The method is capable of fabricating hierarchically structured AgO films with rich nano-porosity and is easily applied to large-scale production. Under the given conditions, ∼300 nm thick Ag films can be oxidized into hierarchically porous AgO nanorod arrays as long as ∼4.2 μm within 60 min. The hierarchically porous AgO films contain at least two levels of porosity ranging from meso-to nano-porosity that are produced by undergoing three different stages, i.e. the oxidation of Ag films, the formation of AgO nanorods, and creation of hierarchical porosity. The hierarchically porous AgO films have the high capacity of trapping light and the large specific area, thus exhibiting excellent photocatalytic activity much better than the solid AgO and TiO₂ films under the UV and visible-light irradiation. In addition, the hierarchically porous AgO films were demonstrated to have potential in energy storage using the assembled Zn-AgO all solid-state thin film battery, which has a specific capacity as high as ∼390 mAh/g.