We report excellent broadband and quasi-omnidirectional antireflective (AR) structures based on highly stable, self-cleaning, mesocrystalline rutile TiO₂ nanorod arrays, which were grown by a facile hydrothermal synthesis directly on Ti foils. Typically, each hierarchical nanorod is a single-crystal-like rutile TiO₂ mesocrystal comprising many [001]-oriented nanotips about 10–30 nm in diameter grown on the top of a [001]-oriented stem nanorod about 100–400 nm in diameter. These novel hierarchical mesostructures exhibit efficient suppression of reflection towards wavelengths ranging from visible to near infrared (NIR) region, with reflection <0.5% in the visible region and <2% in the NIR region, at a wide range of incident angles ranging from nearly normal to 45°. These excellent antireflection properties could be attributed to an optimized graded refractive index profile resulting from the hierarchical tips-on-rod structure of the mesocrystalline nanorods. The chemical and thermal stability of rutile TiO₂ endows the prepared mesocrystalline TiO₂ AR structures with high stability. Moreover, the AR structures exhibit useful self-cleaning properties either under UV irradiation or through fluorosilane-modification.

A general method for facile kinetics-controlled growth of aligned arrays of mesocrystalline SnO₂ nanorods on arbitrary substrates has been developed by adjusting supersaturation in a unique ternary solvent system comprising acetic acid, ethanol, and water. The hydrolysis processes of Sn(IV) as well as the nucleation and growth of SnO₂ crystals were carefully controlled in the mixed solvents, leading to an exclusively heterogeneous nucleation on a substrate and the subsequent growth into mesocrystalline nanorod arrays. In particular, aligned arrays of hierarchically structured, [001]-oriented mesocrystalline SnO₂ nanorods with four {110} lateral facets can be readily grown on Ti foil, as well as many other inert substrates such as fluoride-doped tin oxide (FTO), Si, graphite, and polytetrafluoroethylene (Teflon). Due to the unique combination of the mesocrystalline structure and the one-dimensional nanoarray structure, the obtained mesocrystalline SnO₂ nanorod arrays grown on metallic Ti substrate exhibited an excellent rate performance with a high initial Coulombic efficiency of 65.6% and a reversible capacity of 720 mA·h/g at a charge/discharge rate of 10 C (namely, 7,820 mA/g) when used as an anode material for lithium-ion batteries.