In this paper, we present a novel method to improve the photoelectrocatalytic (PEC) property of TiO2 nanotube arrays (TNTAs) by way of decorating it with visible-light-respond graphitic-C3N4 quantum dots (g-C3N4 QDs). The g-C3N4 QDs/TNTAs heterojunction is successfully prepared using a facile dipping method. The optimal condition of preparing g-C3N4 QDs/TNTAs heterojunction is found as 60 min of dipping duration and 0.2 mg mL(-1) of g-C3N4 QDs dipping solution. The fabricated g-C3N4 QDs/TNTAs heterojunction shows improved PEC activity comparing to TNTAs due to its better separation capability of photo-generated charges and wider optical absorption. And the photocurrent generated by the optimal g-C3N4 QDs/TNTAs photoanode is 4.3 times than that of pristine TNTAs. Besides, the g-C3N4 QDs/TNTAs heterojunction also exhibits superior PEC activities in degradation of phenol. 98.6% of phenol is successfully degraded in 120 min and the pseudo-first-order kinetic constant of phenol degradation is 4.9 times as great as that of pristine TNTAs. This work indicates that the g-C3N4 QDs/TNTAs heterojunction is expected to be a promising nanomaterial for pollutant degradation and further application in solar energy conversion. (C) 2016 Elsevier B.V. All rights reserved.