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 gcat-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.