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

Kouki Oka; Hiroyuki Nishide; Bjorn Winther-Jensen

doi:10.1002/advs.202003077

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

Adv Sci (Weinh). 2021 Jan 20;8(5):2003077. doi: 10.1002/advs.202003077. eCollection 2021 Mar.

Authors

Kouki Oka¹, Hiroyuki Nishide¹, Bjorn Winther-Jensen¹

Affiliation

¹ Department of Applied Chemistry and Research Institute for Science and Engineering Waseda University 3-4-1 Okubo Shinjuku Tokyo 169-8555 Japan.

Abstract

π-Conjugated polymers including polythiophenes are emerging as promising electrode materials for (photo)electrochemical reactions, such as water reduction to H₂ production and oxygen (O₂) reduction to hydrogen peroxide (H₂O₂) 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 O₂ reduction to H₂O₂ production. The very high onset potential of the copolymer for O₂ reduction (+1.53 V vs RHE, pH 12) allows a H₂O₂ production setup with a traditional water-oxidation catalyst, manganese oxide (MnO _x ), as the anode. MnO _x is deposited on one face of a conducting plate, and visible-light illumination of the copolymer layer formed on the other face aids steady O₂ reduction to H₂O₂ with no bias assistance and a complete photocatalytic conversion rate of 14 000 mg (H₂O₂) g_photocat ^-1 h^-1 or ≈0.2 mg (H₂O₂) cm^-2 h^-1.

Keywords: oxygen reduction; polythiophenes; π‐conjugated polymers.