The use of photocatalytic technology to kill bacteria on marine vessel surface coatings has been paid more attention by research scholars. In this paper, petal-like microspheres with Ag nanoparticles were prepared by a simple one-step process combining the hydrothermal method and photodeposition. The 0.7% Ag/Bi 2 O 2 CO 3 composite photocatalyst exhibited the highest photocatalytic efficiency for bacterial removal under visible light irradiation and had the highest photogenerated carrier separation efficiency, and the sterilization rate was doubled compared with that of pure Bi 2 O 2 CO 3 , reaching 95%. Using X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy, the existence of Ag nanoparticles was confirmed, and their size was approximately 10 nm. The surface plasmon resonance (SPR) effect of Ag nanoparticles was investigated by ultraviolet–visible diffuse reflectance spectroscopy (DRS). It was shown that the surface plasmon resonance effect of Ag improved the spectral utilization of the Ag/Bi 2 O 2 CO 3 composite photocatalyst and enhanced the stability of the catalyst. This caused the Ag/Bi 2 O 2 CO 3 composite photocatalyst to have superior photocatalytic activity to pure Bi 2 O 2 CO 3. The results of electrochemical impedance characterization and transient photocurrent response show that 0.7% Ag/Bi 2 O 2 CO 3 has a high efficiency of photogenerated carrier separation. By the free radical capture test, hydroxyl radicals were the primary active substance, and Ag+ improved the photocatalytic sterilization activity. • The SPR effect of Ag can inactivate Marine microorganisms under visible light. • The interaction between Ag+ and hydroxyl radical was used to inactivate Escherichia coli. • The petal-like Bi2O2CO3 was prepared by hydrothermal method. [ABSTRACT FROM AUTHOR]