title: Catecholamine-functionalized graphene as a biomimetic redox shuttle for solar water oxidation.
abstract: In natural photosynthesis, solar energy is converted to chemical energy through a cascaded, photoinduced charge transfer chain that consists of primary and secondary acceptor quinones (i.e., QAand QB). This leads to an exceptionally high near-unity quantum yield. Inspired by the unique multistep architecture of charge transfer in nature, we have synthesized a catecholamine-functionalized, reduced graphene oxide (RGO) film as a redox mediator that can mimic quinone acceptors in photosystem II. We used polynorepinephrine (PNE) as a redox-shuttling chemical. We also used it to coat graphene oxide (GO) and to reduce GO to RGO. The quinone ligands in PNE, which are characterized by a charge transfer involving two electrons and two protons, acted as electron acceptors that facilitated charge transfer in photocatalytic water oxidation. Furthermore, PNE-coated RGO film promoted fast charge separation in [Ru(bpy)3]2+and increased the activity of cobalt phosphate on photocatalytic water oxidation more than two-fold. The results suggest that our bio-inspired strategy for the construction of a forward charge transfer pathway can provide more opportunities to realize efficient artificial photosynthesis.
authors.affiliation: Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 335 Science Road, Daejeon 305-701, Republic of Korea. parkcb@kaist.ac.kr.
authors.forename: Eun Jin
authors.initials: EJ
authors.lastname: Son
authors.forename: Jae Hong
authors.initials: JH
authors.lastname: Kim
authors.forename: Jong Wan
authors.initials: JW
authors.lastname: Ko
authors.forename: Chan Beum
authors.initials: CB
authors.lastname: Park