A TiO2/TiSi2 complex heteronanostructure was synthesized to improve the efficiencies of TiO2 in photosplitting H2O. Photoactive TiO2 served to convert incident photons into separated charges, and the supporting TiSi2 nanonet acted as an efficient conductor to transport separated charges. The structural complexity of TiSi2, also provided a framework of high surface area to enhance photoabsorption. 16.7% peak conversion efficiency was obtained when measured under monochromic UV illuminations. The TiO2, growth was further explored to extend the absorption to the visible range by incorporating W into TiO2, and 0.83% efficiency was measured under simulated solar lights.