New iridium(III) organometallic complexes bearing strong electron donating bidentate ligands as catalysts for water oxidation

Savini, Arianna; Bucci, Alberto; Bellachioma, Gianfranco; Giancola, Stefano; Palomba, Francesco; Rocchigiani, Luca; Rossi, A.; Suriani, Marta; Zuccaccia, Cristiano; Macchioni, Alceo

doi:10.1016/j.jorganchem.2014.05.029

Cited by 36 publications

(26 citation statements)

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“…Successively, many other molecular Ir WOCs were reported, and many excellent and exhaustive reviews recently appeared in the literature , , . Herein, the focus is on the stability and activity of Ir WOCs, two strictly interlocked and crucial aspects.…”

Section: Molecular Ir Wocsmentioning

confidence: 99%

The Middle‐Earth between Homogeneous and Heterogeneous Catalysis in Water Oxidation with Iridium

Macchioni

2018

Eur J Inorg Chem

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Water oxidation (WO) is considered the ideal reaction to provide electrons and protons for the photo‐ and electrosynthesis of renewable fuels, generating exclusively O2 as a benign by‐product. Besides being demanding from the thermodynamic point of view, WO is also extremely difficult from the kinetic one. This has caused an explosion of interest for developing efficient water oxidation catalysts (WOCs). WOCs based on noble metals usually exhibit much better performance. For that reason, parallel to the search for efficient non‐noble metal WOCs, many efforts are directed toward noble‐metal atom economy in WOCs. Three strategies have been proposed to minimizing the atomic contents of noble metals: (1) exploiting molecular WOCs, under the assumption that all metal centers are catalytically active, differently from what happens in heterogeneous WOCs; (2) anchoring a well‐defined molecular WOC onto a suitable support, thus obtaining a heterogenized WOC, combining the positive aspects of homogeneous and heterogeneous catalysis; (3) diluting active metal centers in a suitable material with features that maximize the metal‐accessibility and performance. Herein, the results of our efforts aimed at pursuing all three strategies for developing efficient WOCs based on iridium are reviewed.

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Section: Molecular Ir Wocsmentioning

confidence: 99%

The Middle‐Earth between Homogeneous and Heterogeneous Catalysis in Water Oxidation with Iridium

Macchioni

2018

Eur J Inorg Chem

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“…As a matter of fact, the catalytic site can be properly tuned in term of electron density and steric hindrance at the metal center (a major advantage of homogeneous catalysis) 29 and, at the same time, the catalysts can be easily removed from the reaction mixture through a simple filtration (a big advantage of heterogeneous catalysis). In addition, since the catalytic sites are dispersed onto the surface of the support, associative deactivation processes are minimized.…”

Section: Heterogenized Iridium Catalystsmentioning

confidence: 99%

Homogeneous and heterogenized iridium water oxidation catalysts

Macchioni

2014

SPIE Proceedings

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The development of an efficient catalyst for the oxidative splitting of water into molecular oxygen, protons and electrons is of key importance for producing solar fuels through artificial photosynthesis. We are facing the problem by means of a rational approach aimed at understanding how catalytic performance may be optimized by the knowledge of the reaction mechanism of water oxidation and the fate of the catalytic site under the inevitably harsh oxidative conditions. For the purposes of our study we selected iridium water oxidation catalysts, exhibiting remarkable performance (TOF > 5 s -1 and TON > 20000). In particular, we recently focused our attention on [Cp*Ir(N,O)X] (N,O = 2-pyridincarboxylate; X = Cl or NO 3 ) and [IrCl(Hedta)]Na water oxidation catalysts. The former exhibited a remarkable TOF whereas the latter showed a very high TON. Furthermore, [IrCl(Hedta)]Na was heterogenized onto TiO 2 taking advantage of the presence of a dandling -COOH functionality. The heterogenized catalyst maintained approximately the same catalytic activity of the homogeneous analogous with the advantage that could be reused many times. Mechanistic studies were performed in order to shed some light on the rate-determining step and the transformation of catalysts when exposed to "oxidative stress". It was found that the last oxidative step, preceding oxygen liberation, is the rate-determining step when a small excess of sacrificial oxidant is used. In addition, several intermediates of the oxidative transformation of the catalyst were intercepted and characterized by NMR, X-Ray diffractometry and ESI-MS.

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“…Seminal work by Meyer discovered the first Ru‐based water oxidation catalysts (WOCs), the WOCs containing precious metals, such as ruthenium, iridium, rhodium, had been deeply explored by Bernhard, Brudvig, Macchioni and others group . Among the numbers of works, the catalysts with ligand Cp* (1,2,3,4,5‐pentamethyl‐cycopentadienyl) often showed remarkable catalytic activities for water oxidation . Benefit from the strong π‐donor character, the Cp* unite can stabilize the high oxidation states required by the reaction.…”

Section: Introductionmentioning

confidence: 99%

Half‐sandwich Ir (III) and Rh (III) complexes as catalysts for water oxidation with double‐site

Peng

Liu

Han

et al. 2019

Applied Organom Chemis

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A series of neutral binuclear iridium and rhodium complexes were synthesized based on bis‐imine ligands under mild conditions. These half‐sandwich late transition metal complexes were isolated in good yields and characterized by elemental analysis, 1H NMR, 13C NMR, HR‐MS, and FT‐IR spectroscopies, and the solid state structure of complexes 1 and 2 were further confirmed by single‐crystal X‐ray diffraction. Cyclic voltammetry (CV) characterization indicated that the complex 1 has the best catalyst for water oxidation process with TOF of 0.8 s−1 at low overpotential of 0.325 V in methanol‐phosphate buffer. The proposed double‐site water oxidation mechanism had been also speculated.

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New iridium(III) organometallic complexes bearing strong electron donating bidentate ligands as catalysts for water oxidation

Cited by 36 publications

References 55 publications

The Middle‐Earth between Homogeneous and Heterogeneous Catalysis in Water Oxidation with Iridium

The Middle‐Earth between Homogeneous and Heterogeneous Catalysis in Water Oxidation with Iridium

Homogeneous and heterogenized iridium water oxidation catalysts

Half‐sandwich Ir (III) and Rh (III) complexes as catalysts for water oxidation with double‐site

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