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Photocatalytic water oxidation with cobalt-containing tungstobismutates: Tuning the metal core

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2013
Author Evangelisti Fabio, Car Pierre-Emmanuel, Blacque Olivier, Patzke Greta Ricarda,
Project Homogeneous photocatalytic water splitting
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Original article (peer-reviewed)

Journal Catalysis Science and Technology
Volume (Issue) 3(12)
Page(s) 3117 - 3129
Title of proceedings Catalysis Science and Technology
DOI 10.1039/c3cy00475a


A new type of tungstobismutate water oxidation catalyst (WOC) with a disordered CoW core, [{Co(H2O)3}2{CoBi 2W19O66(OH)4}]10- (1) was tested for visible-light-driven performance and compared to a series of isostructural Co- and Mn-containing polyoxometalates with variable transition metal contents, ([Co2.5(H2O)6{Bi 2W19.5O66(OH)4}]8- (2) and [Mn1.5(H2O)6{Bi2W 20.5O68(OH)2}]6- (3)). All compounds were structurally characterized, and no indications for significant decomposition under catalytic conditions for visible-light-driven water oxidation ([Ru(bpy)3]2+ as photosensitizer (PS) and S 2O8 2- as electron acceptor in different buffer systems) were found. For the first time, subtle differences in the core disorder patterns of isostructural POM-WOCs were revealed to be decisive for the catalytic activity of (1) (maximum TON of 21 with 97% oxygen yield for 115 μM (1)). Performance comparison of the POM series sheds new light on the structure-activity relationships for targeted POM-WOC construction. Indeed, the Co disorder differences between (1) and (2) exclusively affect the sterically more accessible external site of the two crystallographically independent Co core positions which has a 25% higher Co occupancy in (1). This points to a stereoselective reaction pattern for the tetranuclear POM core of WOC (1) which might open up novel construction strategies for the economic redesign of sandwich-type POM-WOCs. In parallel, we demonstrate for the POM series (1)-(3) that electrochemical measurements under catalytic conditions are a promising and convenient pre-screening strategy for WOC activity. Furthermore, POM/PS complex formation of (1) with [Ru(bpy)3]2+ is investigated in detail, and the different roles of Mn- and Co-centers in POM-WOC synthesis are compared. This journal is © The Royal Society of Chemistry.