The enhanced photocatalytic inactivation of marine microorganisms over ZnO supported Ag quantum dots by the synthesis of H2O2.

The production of hydroxyl radicals has been demonstrated to improve the antifouling of marine through a photocatalytic strategy. However, only relying on the valence band of the photocatalyst to generate hydroxyl radicals is inefficient and limits the application of photocatalytic technology in the field of marine-antifouling coatings. Herein, we reported a new strategy in which Ag quantum dots are used to synthesize hydrogen peroxide (H2O2) by photocatalysis in seawater. The decomposition of the generated H2O2 to hydroxyl radicals improves the antifouling ability. Interestingly, the prominent size effect of Ag quantum dots is closely related to the yield of H2O2. We synthesized Ag quantum dots supported on ZnO and found that Ag quantum dots approximately 4 nm in size have the highest activity for H2O2 generation and undergo a 1 h photocatalytic reaction in which the concentration of H2O2 can reach 124 μg/mL. The efficiency of ZnO in inactivating marine microorganisms increased from 72.3% to 99.4% in seawater. The synthesis of H2O2 through photocatalysis based on the medium of seawater can expand the application of photocatalytic technology in the field of marine antifouling.