Controllable synthesis of in situ grown titanate hierarchical microspheres and subsequent chemical modifications for superhydrophobic and oil-water separation properties.

Sodium titanate nanowire-assembled microspheres on titanium mesh have been synthesized through controlling an over the surface acidification and hydrothermal process in terms of a proposed in situ "nucleation-cum-growth" solution chemistry strategy. These directly grown microspheres crystallize in an orthorhombic lepidocrocite layered structure of sodium titanate with the composition of Na 1.8 Ti 1.95 □ 0.05 O 4.8 (□ ∼ vacancy) determined by the XRD, Raman and SEM-EDX techniques. An individual microsphere has a uniform size of around 10 microns while the constituent nanowires have a diameter of 100 nm growing along the [110] orientation. Owing to the specially well-defined hierarchical structure and robust in situ interfaces, these titanate nanowire-assembled microspheres, after 2,2,3,3,4,4,5,5-octafluoro-1-pentanol (OFP) surface modification, could achieve superhydrophobicity. This work demonstrates an in situ "nucleation-cum-growth" synthesis strategy and facile functionalization towards superhydrophobicity for oil-water separation, which might extend to a broad variety of oxide nanowire systems to fabricate well-defined structures for wettability tailoring and multi-functional applications.