title: Heterogeneous and Homogeneous Routes in Water Oxidation Catalysis Starting from Cu(II) Complexes with Tetraaza Macrocyclic Ligands.
abstract: Since the first report in 2012, molecular copper complexes have been proposed as efficient electrocatalysts for water oxidation reactions, carried out in alkaline/neutral aqueous media. However, in some cases the copper species have been recognized as precursors of an active copper oxide layer, electrodeposited onto the working electrode. Therefore, the question whether copper catalysis is molecular or not is particularly relevant in the field of water oxidation. In this study, we investigate the electrochemical activity of copper(II) complexes with two tetraaza macrocyclic ligands, distinguishing heterogeneous or homogeneous processes depending on the reaction media. In an alkaline aqueous solution, and upon application of an anodic bias to working electrodes, an active copper oxide layer is observed to electrodeposit at the electrode surface. Conversely, water oxidation in neutral aqueous buffers is not associated to formation of the copper oxide layer, and could be exploited to evaluate and optimize a molecular, homogeneous catalysis.
authors.affiliation: Department of Chemical Sciences, University of Padova and Institute on Membrane Technology, via Marzolo 1, 35131, Padova, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Prevedello
authors.affiliation: Department of Chemical Sciences, University of Padova and Institute on Membrane Technology, via Marzolo 1, 35131, Padova, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Bazzan
authors.affiliation: Department of Chemical and Pharmaceutical Sciences, University of Ferrara, via Fossato di Mortara 17-27, 44121, Ferrara, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Dalle Carbonare
authors.affiliation: Department of Chemical Sciences, University of Padova and Institute on Membrane Technology, via Marzolo 1, 35131, Padova, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Giuliani
authors.affiliation: TASC-INFM National Laboratory, S.S. 14 Area Science Park, 34012, Basovizza, TS, Italy.
authors.forename: Sunil
authors.initials: S
authors.lastname: Bhardwaj
authors.affiliation: TASC-INFM National Laboratory, S.S. 14 Area Science Park, 34012, Basovizza, TS, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Africh
authors.affiliation: TASC-INFM National Laboratory, S.S. 14 Area Science Park, 34012, Basovizza, TS, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Cepek
authors.affiliation: ISOF-CNR c/o Dept. of Chemical and Pharmaceutical Sciences, University of Ferrara, via L. Borsari, 46-44121, Ferrara, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Argazzi
authors.affiliation: Department of Chemical Sciences, University of Padova and Institute on Membrane Technology, via Marzolo 1, 35131, Padova, Italy.
authors.forename: Marcella
authors.initials: M
authors.lastname: Bonchio
authors.affiliation: Department of Chemical and Pharmaceutical Sciences, University of Ferrara, via Fossato di Mortara 17-27, 44121, Ferrara, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Caramori
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire d'Electrochimie Moléculaire, UMR CNRS N° 7591, Bâtiment Lavoisier, 15 rue Jean de Baïf, 75205, Paris Cedex 13, France. robert@univ-paris-diderot.fr.
authors.forename: Marc
authors.initials: M
authors.lastname: Robert
authors.affiliation: Department of Chemical Sciences, University of Padova and Institute on Membrane Technology, via Marzolo 1, 35131, Padova, Italy. andrea.sartorel@unipd.it.
authors.forename: Andrea
authors.identifier: 0000-0002-4310-3507
authors.initials: A
authors.lastname: Sartorel
keywords: copper; electrocatalysis; homogeneous/heterogeneous; molecular catalysis; oxidation