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 kgH2OH2O2-1), 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.

Automated summary

By integrating visible-light-emitting diodes, optical fibers, and O2-delivering hollow-fiber membranes, we have achieved low-energy and chemical-free photocatalytic production of hydrogen peroxide. This is made possible by utilizing a stable iron-based metal-organic framework photocatalyst fixed onto the optical fibers, improving light utilization and enabling catalyst reusability and O2 supply. The production rate of hydrogen peroxide in pure water is as high as 290 mM h-1 catalyst-g-1, which is 60 times higher than the best-reported values using photocatalytic slurries. The system also has a low energy cost of 2.3 kWh kgH2OH2O2-1 and can sustain high production rates for at least five repeated cycles (2 hours per cycle).