Molybdenum-doped TiO2 nanotube arrays (Mo-doped TiO2 NTs) photoelectrodes with anatase/rutile mixed phase are successfully fabricated via two-step anodization of titanium followed by a hydrothermal doping treatment process. The Mo-doped TiO2 NT material shows higher photocurrent density and enhanced incident photon to current conversion efficiency (IPCE) compared with the pristine TiO2 NTs for photoelectrochemical (PEC) water-splitting. The improvement of PEC response results from not only the increasing of oxygen vacancies and reducing of the recombination of photoexcited charges by Modoping, but also the new formed heterojunctions of anatase/rutile mixed-phase by hydrothermal treatment. Moreover, the Mo-doped TiO2 NTs show high stability and obvious visible absorption with considerable photocurrent density under visible light (lambda > 420 nm). (C) 2015 Elsevier B.V. All rights reserved.