Water oxidation on N-Doped TiO2 nanotube arrays

Photocatalytic splitting water into hydrogen and oxygen by utilizing solar energy is regarded as an effective strategy to solve oil crisis. By utilizing density functional calculations, we herein present the systemic studies with respect to water splitting mechanism on N-doped TiO2 nanotube arrays (NTAs), and focus on activation energy, thermodynamic properties, and effects of N-doping on reaction process. Our results reveal that the impurity 2p states of doped nitrogen effectively change electronic structure of TiO2 NTAs, which act as an electron acceptor and facilitate weakly bound electrons of valence band to be easily excited to acceptor level, as well as enhance the first H2O adsorption and dissociation on the inside wall of N-doped TiO2 NTAs. Therefore, it is found that the rate-determining step of water splitting is the formation reaction of HOO* on N-doped TiO2 NTAs rather than the formation of HO* from the first H2O. (c) 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011