Anodization of titanium in reduced graphene oxide-citric acid electrolyte

•A novel electrolyte system was used for the anodic oxidation of Ti.•High O2− content is beneficial to improve the crystallinity of TiO2.•The samples anodized at 10–50 V display better corrosion resistance. Crystalline oxide film coated pure titanium has been fabricated by anodizing in citric acid (C6H8O7) solution containing reduced graphene oxide (RGO) electrolyte. The voltages ranging from 10 to 90 V were used during the anodization process. The results demonstrate that the growth rate and thickness of barrier layer decrease with the increase of applied voltage. The anodic oxide film mainly consists of anatase TiO2. The sample anodized at 50 V has the highest crystallinity, which is caused by the high lattice oxygen (OL2−) content on the sample surface. When the applied voltages are 10–50 V, the samples exhibit excellent corrosion resistances. Combiningmicrostructure characteristics, it is concluded that the growth of anodic oxide film in the uniformly mixed C6H8O7 and RGO electrolyte is more favorable under low voltages 10–50 V.