Coping with Chloride Ion: Cellulose Acetate-Integrated Ag ₃ PO ₄ @SiO ₂ Films for Efficient Photocatalytic Degradation of Organic Pollutants in Seawater

Organic contamination in seawater presents a significant challenge when using it as a resource for water, hydrogen, and oxygen production. Semiconductor photocatalysis has emerged as an effective method for decontaminating seawater due to its cost-effectiveness and suitability for large-scale applications. However, the high concentration of chloride ions in seawater can inhibit photocatalysis by poisoning the catalyst through surface reactions and scavenging active holes. This study investigates the use of a cellulose acetate (CA) film incorporated with Ag₃PO₄@SiO₂ to decontaminate organic dyes in both simulated and real seawater, where bare Ag₃PO₄ and Ag₃PO₄@SiO₂ are unstable. The film serves as a photocatalytic substrate for degrading dyes, such as methylene blue, Rhodamine B, and Malachite Green, while inhibiting the effects of chloride ions. Our findings indicate a photocatalytic efficiency of 76% in 30 min during the first cycle of methylene blue degradation, with only an ∼15% reduction in efficiency after five photodegradation cycles. The Ag₃PO₄@SiO₂-CA film demonstrated a total degradation of 60.77 mg/L of methylene blue over five cycles. Detailed cyclic voltammetry (CV) studies were conducted to elucidate how the Ag₃PO₄@SiO₂-CA film exhibited superior stability and efficiency as a photocatalyst under chloride-rich conditions.