Several Bi2O3/BiOCI.heterojunction compounds with different Bi2O3/BiOCI ratios were prepared by treating Bi2O3 with HCI. Within the Bi2O3/BiOCI heterojunction, white BiOCI was turned into black by thermal treatment. Upon the result, Bi2O3/black-BiOCI heterojunction could be prepared. The photocatalytic activities of samples were tested depending upon the Bi2O3/BiOCI ratio. Basically, Bi2O3/black-BiOCI samples showed advanced photocatalytic activity compared with the original Bi2O3/white-BiOCI. The highest photocatalytic efficiency was found in the Bi2O3/black-BiOCI when Bi2O3/BiOCI ratio was 15/85. (C) 2017 Elsevier B.V. All rights reserved.