Titanium dioxide (TiO2) has been extensively investigated in solar energy applications, including heterogeneous photocatalysis and photovoltaics. For most TiO2 materials, charge recombination between photoexcited electrons and holes severely limits the efficiencies of solar energy conversion. Different strategies have been attempted to improve charge separation in TiO2 materials. This review focuses on three effective approaches to achieve enhanced charge separation by constructing mixed-phase TiO2, highly dispersed titanium oxides, and nanotubular TiO2 materials. Selected examples from the literature are discussed to demonstrate how the three approaches could be implemented in the context of photocatalytic water splitting, photocatalytic CO2 reduction, and dye-sensitized solar cells. The discussion provides useful insights regarding the design of new TiO2 nanostructures for use in solar energy conversion.