High-Efficiency Photocatalytic H₂O₂ Production in a Dual Optical- and Membrane-Fiber System

Hydrogen peroxide (H₂O₂) is widely used for industrial applications. Currently, ∼95% of H₂O₂ production employs the energy- and chemical-intensive anthraquinone oxidation process. Photocatalytic H₂O₂ production is an emerging alternative process. While advanced material discovery has been a primary focus of photocatalysis, breakthroughs in reactor designs capable of supporting novel materials are lacking. To enable low-energy and chemical-free photocatalytic production of H₂O₂, we integrated visible-light-emitting diodes (41 mW cm^-2), optical fibers, and O₂-delivering hollow-fiber membranes. A stable iron-based metal-organic framework photocatalyst (MIL-101(Fe)) activated by visible light was permanently affixed to the optical fiber, resulting in a uniform and high specific surface area (2650 m² g^-1). The combination of photocatalytic optical fiber and O₂-permeable hollow-fiber membranes is a novel architecture for improving light utilization, photocatalyst reuse, and O₂ supply. The H₂O₂ production rate in pure water was as high as 290 mM h^-1 catalyst-g^-1, which is as much as 60-fold greater than the best-reported values using photocatalytic slurries. The efficient delivery of light also achieved a low energy cost for H₂O₂ production (2.3 kWh kgH₂O_H2O2^-1), and its production rate could be sustained for at least five repeated cycles (2 h per cycle). Energy-efficient H₂O₂ production without chemical inputs makes the dual-fiber system a more sustainable option for H₂O₂ production.