Highly-ordered TiO2 nanotube arrays (TNTAs) were prepared by electrochemical anodization. Cobalt-phosphate (Co-Pi) film fabricated by electrodeposition and Pt nanoparticles (Pt NPs) fabricated by photochemical reduction were decorated onto TNTAs to enhance the photoelectrochemical (PEC) performance together. The photocurrent density of the TNTAs/Co-Pi/Pt photoelectrode could reach 0.185 mA/cm(2) at 1.23 V versus reversible hydrogen electrode under UV lamp illumination (1 mW/cm(2)), which is 2.65 times compared to that of the pure TNTAs photoelectrode. Electrochemistry impedance spectroscopy and Mott-Schottky analysis were conducted to explore the reasons for the enhancement of the PEC performance. Pt NPs could promote the reduction of Co(IV)-oxo intermediate to Co(II) or Co(III) which facilitated the charge transfer in the PEC performance. The result provides a promising guideline to design a simple and efficient photoelectrode for the PEC water-splitting system. (C) 2017 Elsevier B.V. All rights reserved.