Carbon-incorporated titanium dioxide (TiO2) photoelectrodes with different structural features were prepared via rapid-anodic oxidation under different electrical potentials and exposure times. The interstitial carbon arising from the pyrogenation of ethylene glycol electrolytes induced a new C2p occupied state at the bottom of the conduction band, which lowered the band gap energy to similar to 2.3 eV and consequently enabled the visible-light responsiveness. Photoelectrodes with nanotubular structures provided higher photo-conversion efficiency (eta) and hydrogen (H-2) evolution capability than those with irregular structures. The increased aspect ratio, wall thickness, and pore size of the nanotube arrays contributed to eta through greater photon excitation and penetration. However, this contribution is limited by the high recombination of the charge carriers at ultra-high aspect ratios. Photoelectrodes with a nanotube length of similar to 19.5 mu m, pore size of similar to 103 nm, wall thickness of similar to 17 nm, and aspect ratio of similar to 142.5 exhibited remarkable capability to generate H2 at an evolution rate of up to similar to 508.3 mu L min(-1) cm(-2) and eta of similar to 2.3%. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.