Photocatalytic HO production from water and air using porous organic polymers.

Producing hydrogen peroxide (HO) from HO and O under visible light irradiation is a promising solar-to-chemical energy conversion technology. Hydrogen peroxide has versatile applications as a green oxidant and liquid energy carrier but has been produced through energy-intensive and complex anthraquinone processes. Herein, we report the rational design of efficient and stable porous organic polymer (POP) containing redox centers, anthraquinone photocatalyst (ANQ-POP) for solar HO production. ANQ-POP is readily synthesized with stable dioxin-linkages via efficient one-pot, transition-metal-free nucleophilic aromatic substitution reactions between 1,2,3,4,5,6,7,8-octafluoro-9,10-anthraquinone (OFANQ) and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP). Exhibiting a fibrillar morphology, ANQ-POP boasts a high surface area of 380 m∙g and demonstrates thermal stability. With 10 % ethanol, ANQ-POP yields an HO production rate of 320 μmol g under visible light irradiation. Moreover, ANQ-POP alone can efficiently produce HO without any photosensitizers and cocatalysts. Density functional theory calculations reveal that the quinone groups of the anthraquinone moieties can serve as redox centers for HO production under light irradiation. Furthermore, unlike most conventional photocatalysts, it can produce HO using only water and air by catalyzing both oxygen reduction and evolution reactions under light irradiation. Our findings provide an efficient, eco-friendly pathway for photocatalytic production of HO under mild reaction conditions using a dioxin-derived POP-based photocatalyst.