Copolymer of Phenylene and Thiophene toward a Visible-Light-Driven Photocatalytic Oxygen Reduction to Hydrogen Peroxide.

-Conjugated polymers including polythiophenes are emerging as promising electrode materials for (photo)electrochemical reactions, such as water reduction to H production and oxygen (O) reduction to hydrogen peroxide (HO) production. In the current work, a copolymer of phenylene and thiophene is designed, where the phenylene ring lowers the highest occupied molecular orbital level of the polymer of visible-light-harvesting thiophene entities and works as a robust catalytic site for the O reduction to HO production. The very high onset potential of the copolymer for O reduction (+1.53 V vs RHE, pH 12) allows a HO production setup with a traditional water-oxidation catalyst, manganese oxide (MnO ), as the anode. MnO is deposited on one face of a conducting plate, and visible-light illumination of the copolymer layer formed on the other face aids steady O reduction to HO with no bias assistance and a complete photocatalytic conversion rate of 14 000 mg (HO) g h or ≈0.2 mg (HO) cm h.