Hierarchical TiO2/g-C3N4 heterojunction photocatalysts with well-defined multiscale porous TiO2 framework are synthesized by simply calcinating tetrabutyl titanate and melamine precursors. The samples have been characterized by XRD, XPS, SEM, TEM, FTIR, nitrogen absorption-desorption equipment and TGA. The photocatalytic activity of these samples has been investigated in photo-degradation of Rhodamine B (RhB). The results show that calcining temperature critically affects the microstructure, surface area, interface structure and catalytic properties of the prepared samples. At the optimal calcining temperature of 550 degrees C, the apparent reaction rate constant of the catalyst is 55.0 x 10(-3) min(-1), which is 16.2 fold of pure TiO2 (3.4 x 10(-3) min(-1)) and 3.4 fold of pure g-C3N4 (16.4 x 10(-3) min(-1)), respectively. The strengthened visible-light-driven photocatalytic activity is attributed to the formation of a unique Z scheme TiO2/g-C3N4 heterojunction due to C- or N-doping at the surface of the porous TiO2 framework. This mechanism explains the observation in a series of radical trapping experiments that superoxide ions and photo-generated holes play major roles in the photo-decolorizing process while hydroxyl radicals are also involved with a minor role. (C) 2018 Elsevier B.V. All rights reserved.