Abstract
Light-driven water oxidation is achieved with the Ru(bpy)3 2+/S2O8 2- cycle employing the highly active Ir-blue water oxidation catalyst, namely, an IrIV,IV 2(pyalc)2 μ-oxo-dimer [pyalc = 2-(2′-pyridyl)-2-propanoate]. Ir-blue is readily formed by stepwise oxidation of the monomeric Ir(III) precursor 1 by the photogenerated Ru(bpy)3 3+, with a quantum yield φ of up to 0.10. Transient absorption spectroscopy and kinetic evidence point to a stepwise mechanism, where the primary event occurs via a fast photoinduced electron transfer from 1 to Ru(bpy)3 3+, leading to the Ir(IV) monomer I1 (k1 ∼108 M-1 s-1). The competent Ir-blue catalyst is then obtained from I1 upon photooxidative loss of the Cp∗ ligand and dimerization. The Ir-blue catalyst is active in the Ru(bpy)3 2+/S2O8 2- light-driven water oxidation cycle, where it undergoes two fast photoinduced electron transfers to Ru(bpy)3 3+ [with kIr-blue = (3.00 ± 0.02) × 108 M-1 s-1 for the primary event, outperforming iridium oxide nanoparticles by ca. 2 orders of magnitude], leading to a IrV,V 2 steady-state intermediate involved in O-O bond formation. The quantum yield for oxygen evolution depends on the photon flux, showing a saturation regime and reaching an impressive value of φ(O2) = 0.32 ± 0.01 (corresponding to a quantum efficiency of 64 ± 2%) at low irradiation intensity. This result highlights the key requirement of orchestrating the rate of the photochemical events with dark catalytic turnover.
| Original language | English |
|---|---|
| Journal | Inorganic Chemistry |
| DOIs | |
| Publication status | Accepted/In press - Jan 1 2019 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
Cite this
Light-Driven Water Oxidation with the Ir-blue Catalyst and the Ru(bpy)3 2+/S2O8 2- Cycle : Photogeneration of Active Dimers, Electron-Transfer Kinetics, and Light Synchronization for Oxygen Evolution with High Quantum Efficiency. / Volpe, Andrea; Tubaro, Cristina; Natali, Mirco; Sartorel, Andrea; Brudvig, Gary W.; Bonchio, Marcella.
In: Inorganic Chemistry, 01.01.2019.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Light-Driven Water Oxidation with the Ir-blue Catalyst and the Ru(bpy)3 2+/S2O8 2- Cycle
T2 - Photogeneration of Active Dimers, Electron-Transfer Kinetics, and Light Synchronization for Oxygen Evolution with High Quantum Efficiency
AU - Volpe, Andrea
AU - Tubaro, Cristina
AU - Natali, Mirco
AU - Sartorel, Andrea
AU - Brudvig, Gary W.
AU - Bonchio, Marcella
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Light-driven water oxidation is achieved with the Ru(bpy)3 2+/S2O8 2- cycle employing the highly active Ir-blue water oxidation catalyst, namely, an IrIV,IV 2(pyalc)2 μ-oxo-dimer [pyalc = 2-(2′-pyridyl)-2-propanoate]. Ir-blue is readily formed by stepwise oxidation of the monomeric Ir(III) precursor 1 by the photogenerated Ru(bpy)3 3+, with a quantum yield φ of up to 0.10. Transient absorption spectroscopy and kinetic evidence point to a stepwise mechanism, where the primary event occurs via a fast photoinduced electron transfer from 1 to Ru(bpy)3 3+, leading to the Ir(IV) monomer I1 (k1 ∼108 M-1 s-1). The competent Ir-blue catalyst is then obtained from I1 upon photooxidative loss of the Cp∗ ligand and dimerization. The Ir-blue catalyst is active in the Ru(bpy)3 2+/S2O8 2- light-driven water oxidation cycle, where it undergoes two fast photoinduced electron transfers to Ru(bpy)3 3+ [with kIr-blue = (3.00 ± 0.02) × 108 M-1 s-1 for the primary event, outperforming iridium oxide nanoparticles by ca. 2 orders of magnitude], leading to a IrV,V 2 steady-state intermediate involved in O-O bond formation. The quantum yield for oxygen evolution depends on the photon flux, showing a saturation regime and reaching an impressive value of φ(O2) = 0.32 ± 0.01 (corresponding to a quantum efficiency of 64 ± 2%) at low irradiation intensity. This result highlights the key requirement of orchestrating the rate of the photochemical events with dark catalytic turnover.
AB - Light-driven water oxidation is achieved with the Ru(bpy)3 2+/S2O8 2- cycle employing the highly active Ir-blue water oxidation catalyst, namely, an IrIV,IV 2(pyalc)2 μ-oxo-dimer [pyalc = 2-(2′-pyridyl)-2-propanoate]. Ir-blue is readily formed by stepwise oxidation of the monomeric Ir(III) precursor 1 by the photogenerated Ru(bpy)3 3+, with a quantum yield φ of up to 0.10. Transient absorption spectroscopy and kinetic evidence point to a stepwise mechanism, where the primary event occurs via a fast photoinduced electron transfer from 1 to Ru(bpy)3 3+, leading to the Ir(IV) monomer I1 (k1 ∼108 M-1 s-1). The competent Ir-blue catalyst is then obtained from I1 upon photooxidative loss of the Cp∗ ligand and dimerization. The Ir-blue catalyst is active in the Ru(bpy)3 2+/S2O8 2- light-driven water oxidation cycle, where it undergoes two fast photoinduced electron transfers to Ru(bpy)3 3+ [with kIr-blue = (3.00 ± 0.02) × 108 M-1 s-1 for the primary event, outperforming iridium oxide nanoparticles by ca. 2 orders of magnitude], leading to a IrV,V 2 steady-state intermediate involved in O-O bond formation. The quantum yield for oxygen evolution depends on the photon flux, showing a saturation regime and reaching an impressive value of φ(O2) = 0.32 ± 0.01 (corresponding to a quantum efficiency of 64 ± 2%) at low irradiation intensity. This result highlights the key requirement of orchestrating the rate of the photochemical events with dark catalytic turnover.
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U2 - 10.1021/acs.inorgchem.9b02531
DO - 10.1021/acs.inorgchem.9b02531
M3 - Article
C2 - 31774669
AN - SCOPUS:85076169207
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
ER -