Abstract
TiO 2 is one of the most promising photoanodes for solar-hydrogen conversion by water splitting. However, the solar-hydrogen efficiency of TiO 2 remains limited because of a low photocurrent generation. A clear understanding of photoexcitations within photoanodes can predict the quantity of photocurrent and consequently determine the solar-hydrogen efficiency. In this work, hydrothermally synthesized rutile TiO 2 nanorods were investigated for their photoelectrochemical (PEC) performance. A photogenerated hole concentration of TiO 2 photoanode was derived as 8.40 × 10 14 cm -3 under one sun illumination. In addition, Fermi level pinning associated with high density of surface states was also observed under PEC operation. Base on these results, a series of band diagrams of TiO 2 photoanode were established to describe the photogeneration of holes and current at various bias potential. The main limitation of photocurrent generation is the distribution of surface-trapped states, which determines the hole concentration at the surface and consequently determines the open-circuit potential and the photocurrent density. © 2013 Elsevier B.V. All rights reserved.