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Heterogeneous and Homogeneous Routes in Water Oxidation Catalysis Starting from Cu II Complexes with Tetraaza Macrocyclic Ligands
Author(s) -
Prevedello Andrea,
Bazzan Irene,
Dalle Carbonare Nicola,
Giuliani Angela,
Bhardwaj Sunil,
Africh Cristina,
Cepek Cinzia,
Argazzi Roberto,
Bonchio Marcella,
Caramori Stefano,
Robert Marc,
Sartorel Andrea
Publication year - 2016
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201501446
Subject(s) - homogeneous , catalysis , homogeneous catalysis , chemistry , computational chemistry , inorganic chemistry , combinatorial chemistry , organic chemistry , thermodynamics , physics
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.