Based on the crystal structure and the DFT calculation of Bi2O2CO3, I- can partly replace the CO32--in Bi2O2CO3 to narrow its bandgap and to enhance its visible light absorption. With this in mind, roselike I-doped Bi2O2CO3 microspheres were prepared via a hydrothermal process. This method can also be extended to synthesize rose-like Cl- or Br-doped Bi2O2CO3 microspheres. Photoelectrochemical test supports the OFT calculation result that I- doping narrows the bandgap of Bi2O2CO3 by forming two intermediate levels in its forbidden band. Further study reveals that I-doped Bi2O2CO3 microspheres with optimized composition exhibit the best photocatalytic activity. Rhodamine B can be completely degraded within 6 min and about 90% of Cr(VI) can be reduced after 25 min under the irradiation of visible light (lambda > 400 nm). (C) 2016 Elsevier B.V. All rights reserved.