Three-Dimensional CdS-Sensitized Sea Urchin Like TiO₂‑Ordered Arrays as Efficient Photoelectrochemical Anodes

We demonstrate the fabrication of a 3D ordered sea urchin like TiO₂ structure by combining colloidal spheres template, atomic layer deposition (ALD), and hydrothermal growth method. The 3D sea urchin like TiO₂ arrays as photoanode present improved photoelectrochemical performance in contrast to 2D TiO₂ hollow microspheres and 1D TiO₂ nanowires arrays. With CdS quantum dots sensitization, the sea urchin like TiO₂ array photoanode yields a photocurrent of 5.4 mA cm^–2 at 0 V vs Ag/AgCl. The performance improvement is attributed to the increased specific surface area and porosity, light trapping effect by multiscattering of the hierarchical structure, as well as direct charge transportation paths from the nanorods to the microspheres.