Carbon-incorporated TiO2 photoelectrodes prepared via rapid-anodic oxidation for efficient visible-light hydrogen generation (original) (raw)

Hydrogen energy Photoelectrochemical process a b s t r a c t Carbon-incorporated titanium dioxide (TiO 2 ) 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 w2.3 eV and consequently enabled the visible-light responsiveness. Photoelectrodes with nanotubular structures provided higher photoconversion efficiency (h) 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 h 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 w19.5 mm, pore size of w103 nm, wall thickness of w17 nm, and aspect ratio of w142.5 exhibited remarkable capability to generate H 2 at an evolution rate of up to w508.3 mL min À1 cm À2 and h of w2.3%.