Bridging Materials Innovation with an Efficient Photocatalyst-Enabled Optical Fiber Reactor for H₂O₂ Production

Hydrogen peroxide (H₂O₂) is a green oxidant widely used in water treatment and sustainable chemistry. Although many advanced materials exist for photo- and electrocatalytic production, H₂O₂ output and stability depend on reactor design and water quality. This study explores a scalable photochemical system employing bismuth vanadate-coated polymeric optical fibers (POF-BVO) illuminated by 440 nm LEDs. A single 20 cm, 3 mm diameter fiber generates H₂O₂ at 4.3 mg H₂O₂ h^-1 (430 mg H₂O₂ g_cat^-1 h^-1), with enhanced rates achieved using bundled fibers. The bundled configuration increases fiber packing density in the reactor to >120 m² m^-3, tripling that of flat-plate photocatalytic reactors. High H₂O₂ production is achieved using oxygen-permeable hollow-fiber membranes to deliver pure O₂ or air. The system performs consistently across pH 4-9 and in tap water, wastewater, or seawater. Phosphate ions improve H₂O₂ stability, resulting in higher concentrations. Over 21 days of continuous operation, the system produces >6 g L^-1 of H₂O₂ with minimal performance degradation. Energy analysis reveals a 2-30x reduction in energy use compared to traditional slurry-based photocatalytic systems, with a three-fiber bundle reaching 27 kWh kg^-1─comparable to electrochemical processes. These results demonstrate the potential of the POF-BVO platform as an energy-efficient and modular solution for decentralized H₂O₂ production.