Novel synthesis of N-doped TiO2 flower-like microspheres with excellent photocatalytic activity for removal of Cr(VI) and methylene blue

•N-TFMs were prepared by a novel solvothermal route followed by calcination.•N doping was achieved without adding additional nitrogen source during annealing.•N-TFMs were assembled from ultrathin nanosheets with a thickness of ca. 3 nm.•Photocatalytic activity of N-TFMs is much higher than that of commercial P25 TiO2.