TiO2 nanotubes (TNTs) were doped with reduced graphene oxide (RGO) via anodization. The synthesized catalyst was characterized by FE-SEM, XRD, AES, PL, Raman, and UV-vis DRS. We have synthesized the catalyst with different RGO doping time and RGO concentration. The optimum synthesis conditions for RGO doping were a 0.5 g L-1 RGO anodization at 60 V for 1 min. Compared with un-doped TNTs, the RGO-doped TNT photocatalyst showed a 3.8-fold higher photocatalytic activity, while phenol degradation under visible light irradiation. Optimum phenol degradation was observed at an external bias of 0.5 V using a photoelectrocatalytic method, and this degradation rate was 3.5-fold higher than that observed for un-doped TNTs. The intermediate products of phenol were also analyzed using TD-GC-MS method to evaluate the phenol degradation pathways. The RGO-doped TNTs reduced the recombination of photo-induced e- and h(+) and thus increased the formation of the OH radicals and superoxides that degrade phenol. (C) 2017 Elsevier B.V. All rights reserved.