Tandem Proton Transfer in Carboxylated Supramolecular Polymer for Highly Efficient Overall Photosynthesis of Hydrogen Peroxide.

Proton supply is as critical as O 2 activation for artificial photosynthesis of hydrogen peroxide (H 2 O 2 ) via two-electron oxygen reduction reaction (2e - ORR). However, proton release via water dissociation is frequently hindered because of the sluggish water oxidation reaction (WOR), extremely limiting the efficiency of photocatalytic H 2 O 2 production. To tackle this challenge, carboxyl-enriched supramolecular polymer (perylene tetracarboxylic acid-PTCA) is elaborately prepared by molecular self-assembly for overall photosynthesis of H 2 O 2 . Interestingly, the interconversion between carboxyl as Brønsted acid and its conjugated base realizes rapid proton circulation. Through this efficient tandem proton transfer process, the spatial effect of photocatalytic reduction and oxidation reaction is greatly enhanced with reduced reaction barrier. This significantly facilitates 2e - photocatalytic ORR to synthesize H 2 O 2 and in the meanwhile promotes 4e - photocatalytic WOR to evolve O 2 . Consequently, the as-developed PTCA exhibits a remarkable H 2 O 2 yield of 185.6 μM h -1 in pure water and air atmosphere under visible light illumination. More impressively, an appreciable H 2 O 2 yield of 78.6 μM h -1 can be well maintained in an anaerobic system owing to in situ O 2 generation by 4e - photocatalytic WOR. Our study presents a novel concept for artificial photosynthesis of H 2 O 2 via constructing efficient proton transfer pathway to enable rapid proton circulation.