Effect of mixed-phase TiO2 doped with Ca2+ on charge transfer at the TiO2/graphene interface

•The Ca2+-doped mixed-phase TiO2 was prepared by hydrothermal method, and the Ca2+-doped mixed-phase TiO2/graphene composites were synthesized by one-step self-assembly method.•The synergistic effect of mixed-phase TiO2 and Ca2+ significantly enhances the carrier concentration as well as the TiO2/G interfacial transfer rate.•Such Ca2+-doped mixed-phase TiO2/graphene composites have promising applications in the field of conductive coatings.