Hollow hierarchical spheres self-organized from the ultrathin nanosheets of a-Fe 2 O 3 were prepared by a simple process. These ultrathin nanosheet subunits possess an average thickness of around 3.5 nm and show preferential exposure of (110) facets. Their Li ion storage and visible-light photocatalytic water oxidation performance are tested. Such hierarchical nanostructures show high Li storage properties with good cycling stability and excellent rate capabilities. The water oxidation catalytic activity is 70 mmol h ร1 g ร1 for O 2 evolution under visible light irradiation and can be maintained for 15 hours. The structural features of these a-Fe 2 O 3 nanocrystals are considered to be important to lead to the attractive properties in both Li storage and photocatalytic water oxidation, e.g. hollow interior, ultrathin thickness and largely exposed active facets.
Broader context
Advanced materials development is one of the keys to achieve high performance of energy devices. In this work, hollow Fe 2 O 3 nanospheres composed of thin sheets are prepared by a facile templating process. The Fe 2 O 3 thin sheets in the spheres are $3.5 nm thick and show preferential exposure of (110) facets. These features are useful to achieve attractive performance when used as an anode of a Li ion battery and as a photocatalyst for water oxidation. Thus, these Fe 2 O 3 hollow spheres are useful to build energy storage and fuel generation devices.