Covalent organic frameworks for direct photosynthesis of hydrogen peroxide from water, air and sunlight.

Solar-driven photosynthesis is a sustainable process for the production of hydrogen peroxide, the efficiency of which is plagued by side reactions. Metal-free covalent organic frameworks (COFs) that can form suitable intermediates and inhibit side reactions show great promise to photo-synthesize HO. However, the insufficient formation and separation/transfer of photogenerated charges in such materials restricts the efficiency of HO production. Herein, we provide a strategy for the design of donor-acceptor COFs to greatly boost HO photosynthesis. We demonstrate that the optimal intramolecular polarity of COFs, achieved by using suitable amounts of phenyl groups as electron donors, can maximize the free charge generation, which leads to high HO yield rates (605 μmol g h) from water, oxygen and visible light without sacrificial agents. Combining in-situ characterization with computational calculations, we describe how the triazine N-sites with optimal N 2p states play a crucial role in HO activation and selective oxidation into HO. We further experimentally demonstrate that HO can be efficiently produced in tap, river or sea water with natural sunlight and air for water decontamination.