An inexpensive CuO nanoparticles as cocatalyst significantly enhanced the photo-oxidation performance of Bi2Ga2.8Al1.2O9 photocatalyst under visible-light

[Display omitted] •The CuO highly improved the absorption ability in visible light region.•Doping Al into Bi2Ga4O9 presented high photo-oxidation activity and low cost.•The BGAO-2.5%Cu exhibited the highest photo-oxidation activity.•The photo-generated hole played a main role for the RhB degradation. Herein, we present a systematic investigation of CuO nanoparticles decorated on Bi2Ga2.8Al1.2O9 semiconducting photocatalyst for the photo-oxidation rhodamine B (RhB) under visible-light. Under the same condition, all cocatalysts (CuO, Ag, Au, Pt and Co) enhanced the photocatalytic activity than the intrinsic Bi2Ga2.8Al1.2O9 photocatalyst, where the BGAO-2.5%Cu photocatalyst show the highest photo-oxidation activity. The kinetic constant (k) of the obtained optimal photocatalyst is 3.9 and 5.7 times than those of Bi2Ga2.8Al1.2O9 and Bi2Ga4O9 semiconductors, respectively. The photo-oxidation efficiency of RhB is 99.14% over the optimal photocatalyst in 2 h. The possible photocatalytic mechanism of the function of CuO on the semiconductor is proposed. This work highlight the CuO which was decorated on semiconductor by a simple photodeposition method play an essential role for the environmental cleaning.