title: Single-site copper(II) water oxidation electrocatalysis: rate enhancements with HPO₄²⁻ as a proton acceptor at pH 8.
abstract: The complex Cu(II)(Py3P) (1) is an electrocatalyst for water oxidation to dioxygen in H2PO4(-)/HPO4(2-) buffered aqueous solutions. Controlled potential electrolysis experiments with 1 at pH 8.0 at an applied potential of 1.40 V versus the normal hydrogen electrode resulted in the formation of dioxygen (84% Faradaic yield) through multiple catalyst turnovers with minimal catalyst deactivation. The results of an electrochemical kinetics study point to a single-site mechanism for water oxidation catalysis with involvement of phosphate buffer anions either through atom-proton transfer in a rate-limiting O-O bond-forming step with HPO4(2-) as the acceptor base or by concerted electron-proton transfer with electron transfer to the electrode and proton transfer to the HPO4(2-) base.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516 (USA).
authors.forename: Michael K
authors.initials: MK
authors.lastname: Coggins
authors.forename: Ming-Tian
authors.initials: MT
authors.lastname: Zhang
authors.forename: Zuofeng
authors.initials: Z
authors.lastname: Chen
authors.forename: Na
authors.initials: N
authors.lastname: Song
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Meyer
keywords: copper; electrocatalysis; electrochemistry; homogeneous catalysis; water oxidation