Designing a 0D/3D foamy CeO2/(ZnOxSy)n heterojunction for visible-light photocatalytic antibacterial and marine antifouling applications

Porous semiconductor heterojunctions offer a powerful platform for enhancing charge separation and photocatalytic efficiency; however, achieving robust visible-light-driven antibacterial and antifouling performance remains challenging. Herein, a foam-structured CeO 2 /(ZnOₓS y )ₙ heterojunction (Ce/(ZOS) n ) was rationally engineered via a coffee-extract-assisted synthesis-blending strategy to overcome the limited visible-light activity of CeO 2 and the weak hydroxyl radical (•OH) generation of ZnO and ZnS. Among the series, Ce/(ZOS) 2 exhibits optimal performance, achieving near-complete (∼100%) inactivation of both Gram-negative ( Pseudomonas aeruginosa ) and Gram-positive ( Staphylococcus aureus ) under visible-light irradiation (λ ≥ 420 nm, 12 h). Notably, real sea immersion tests over 60 days demonstrate almost no macrofouling on Ce/(ZOS) 2 , in stark contrast to severe biofouling on control samples. Photoelectrochemical analyses reveal that Ce/(ZOS) 2 possesses the lowest charge-transfer resistance, highest photocurrent density, and prolonged carrier lifetime (9.23 ns), confirming efficient charge separation. Its optimized bandgap (2.85 eV) and n-n quasi-Type-II heterojunction facilitate directional electron transfer and suppress recombination. Electron paramagnetic resonance further confirms significantly enhanced generation of •O 2 − and •OH radicals, driving rapid oxidative bacterial inactivation. Overall, this work establishes foam-structured Ce/(ZOS) n heterojunctions as highly efficient, visible-light-responsive materials, offering a promising and scalable strategy for next-generation marine antibiofouling and antibacterial coatings.