P25 niblet-like coated on large void space TiO2 nanotubes arrays for high-rate charge-collection and improved photoconversion efficiency

► A large void space TiO2 nanotubes arrays (LTAs) was fabricated in not more than 12 h. ► A niblet-like P25-coated void space TiO2 nanotubes arrays (PCTs) has been synthesized based on the LTAs. ► Some key factors, probable synthetic mechanisms and optimal synthetic route are investigated. ► The PCTs and LTAs show impressive morphologies, structures and greatly improved dye loading capability. ► The PCTs shows enhanced charge-collection and light scattering properties and double solar cell efficiency.