High-Efficiency Catalyst-Free Photosynthesis of H2O2 from Dibenzyl Ether and Oxygen

Photosynthesis of hydrogen peroxide (H2O2) driven by sunlight is a promising and environmentally friendly route for industrialization with great attraction, but the extremely low apparent quantum yield (AQY) of the predominant photocatalytic processes evoked by the natural shortcomings of current photocatalysts hinder its actual scale-up application. In this work, a photocatalyst-free H2O2 photosynthesis route is developed based on photoreaction between dibenzyl ether (DE) and oxygen with an impressive 52.41% AQY (λ = 313 nm). The H2O2 generation rate is as high as 119.50 mM·h–1 at 20 °C, and the maximum H2O2 yield reaches 2389.92 mM, basically meeting the demand for industrialization and far beyond that of current photocatalytic systems. Such a surprising H2O2 yield via photoreaction of DE ascribes to the homolysis of C–H and C–O bonds under UV irradiation, evoking the generation of hydrogen, benzyl, and alkyl oxygen radicals and subsequently producing H2O2 with O2 via the oxygen reduction reaction pathway. The byproduct, benzaldehyde (BD), further promotes the H2O2 yield. The final product, benzoin, suggests the presence of BD condensation and improves the process economy. These findings contribute a feasible method for actual large-scale application of H2O2 photosynthesis and a protocol for synthesizing organic molecules based on C–O and C–H bonds.