Kinetics of electron transfer and oxygen evolution in the reaction of [Ru(bpy) 3] 3+ with colloidal iridium oxide

Natalie D. Morris; Masahiro Suzuki; Thomas E. Mallouk

doi:10.1021/jp0480145

Kinetics of electron transfer and oxygen evolution in the reaction of [Ru(bpy) ₃] ³⁺ with colloidal iridium oxide

Natalie D. Morris, Masahiro Suzuki, Thomas E. Mallouk

Research output: Contribution to journal › Article › peer-review

141 Scopus citations

Abstract

The kinetics of electron transfer and oxygen evolution at citrate-stabilized IrO _x·nH ₂O colloids were studied by time-resolved UV-visible spectrosopy and by steady-state photolysis of [Ru(bpy) ₃] ²⁺ (bpy = 2,2′-bipyridyl) and persulfate in a hexafluorosilicate/bicarbonate buffer. Time-resolved studies of the reaction of [Ru(bpy) ₃] ³⁺ with these colloids show an initial fast electron transfer, corresponding to oxidation of Ir(III) to Ir(IV). Further oxidation of surface Ir atoms occurs concomitantly with oxygen evolution with a second-order rate constant of 1.3 × 10 ⁶ M ^-1 s ^-1. Both the time-resolved reduction of [Ru(bpy) ₃] ⁺³ by IrO _x·nH ₂O and the photocatalytic oxygen evolution under non-light-limited photolysis conditions have a H/D kinetic isotope effect (KIE) of 1.0. This contrasts with significantly higher KIE values for oxygen evolution from molecular cis,cis-[(bpy) ₂Ru-(OH ₂)] ₂O] ⁴⁺ and [(terpy)(H ₂O)Mn ^III(O) ₂(OH ₂)terpy)] ^3- water oxidation catalysts. This is consistent with the conclusion that, under the conditions of most photocatalytic experiments (∼10 ^-4 M [Ru(bpy) ₃] ²⁺ concentration), electron transfer from the colloid to the oxidized sensitizer rather than formation of a surface-bound hydroperoxy species is the rate-determining step in photocatalytic oxygen evolution.

Original language	English (US)
Pages (from-to)	9115-9119
Number of pages	5
Journal	Journal of Physical Chemistry A
Volume	108
Issue number	42
DOIs	https://doi.org/10.1021/jp0480145
State	Published - Oct 21 2004

All Science Journal Classification (ASJC) codes

Physical and Theoretical Chemistry

Access to Document

10.1021/jp0480145

Cite this

@article{e8ca229a2ae94089acfeae08e39c8fd1,

title = "Kinetics of electron transfer and oxygen evolution in the reaction of [Ru(bpy) 3] 3+ with colloidal iridium oxide",

abstract = "The kinetics of electron transfer and oxygen evolution at citrate-stabilized IrO x·nH 2O colloids were studied by time-resolved UV-visible spectrosopy and by steady-state photolysis of [Ru(bpy) 3] 2+ (bpy = 2,2′-bipyridyl) and persulfate in a hexafluorosilicate/bicarbonate buffer. Time-resolved studies of the reaction of [Ru(bpy) 3] 3+ with these colloids show an initial fast electron transfer, corresponding to oxidation of Ir(III) to Ir(IV). Further oxidation of surface Ir atoms occurs concomitantly with oxygen evolution with a second-order rate constant of 1.3 × 10 6 M -1 s -1. Both the time-resolved reduction of [Ru(bpy) 3] +3 by IrO x·nH 2O and the photocatalytic oxygen evolution under non-light-limited photolysis conditions have a H/D kinetic isotope effect (KIE) of 1.0. This contrasts with significantly higher KIE values for oxygen evolution from molecular cis,cis-[(bpy) 2Ru-(OH 2)] 2O] 4+ and [(terpy)(H 2O)Mn III(O) 2(OH 2)terpy)] 3- water oxidation catalysts. This is consistent with the conclusion that, under the conditions of most photocatalytic experiments (∼10 -4 M [Ru(bpy) 3] 2+ concentration), electron transfer from the colloid to the oxidized sensitizer rather than formation of a surface-bound hydroperoxy species is the rate-determining step in photocatalytic oxygen evolution.",

author = "Morris, {Natalie D.} and Masahiro Suzuki and Mallouk, {Thomas E.}",

year = "2004",

month = oct,

day = "21",

doi = "10.1021/jp0480145",

language = "English (US)",

volume = "108",

pages = "9115--9119",

journal = "Journal of Physical Chemistry A",

issn = "1089-5639",

publisher = "American Chemical Society",

number = "42",

}

TY - JOUR

T1 - Kinetics of electron transfer and oxygen evolution in the reaction of [Ru(bpy) 3] 3+ with colloidal iridium oxide

AU - Morris, Natalie D.

AU - Suzuki, Masahiro

AU - Mallouk, Thomas E.

PY - 2004/10/21

Y1 - 2004/10/21

N2 - The kinetics of electron transfer and oxygen evolution at citrate-stabilized IrO x·nH 2O colloids were studied by time-resolved UV-visible spectrosopy and by steady-state photolysis of [Ru(bpy) 3] 2+ (bpy = 2,2′-bipyridyl) and persulfate in a hexafluorosilicate/bicarbonate buffer. Time-resolved studies of the reaction of [Ru(bpy) 3] 3+ with these colloids show an initial fast electron transfer, corresponding to oxidation of Ir(III) to Ir(IV). Further oxidation of surface Ir atoms occurs concomitantly with oxygen evolution with a second-order rate constant of 1.3 × 10 6 M -1 s -1. Both the time-resolved reduction of [Ru(bpy) 3] +3 by IrO x·nH 2O and the photocatalytic oxygen evolution under non-light-limited photolysis conditions have a H/D kinetic isotope effect (KIE) of 1.0. This contrasts with significantly higher KIE values for oxygen evolution from molecular cis,cis-[(bpy) 2Ru-(OH 2)] 2O] 4+ and [(terpy)(H 2O)Mn III(O) 2(OH 2)terpy)] 3- water oxidation catalysts. This is consistent with the conclusion that, under the conditions of most photocatalytic experiments (∼10 -4 M [Ru(bpy) 3] 2+ concentration), electron transfer from the colloid to the oxidized sensitizer rather than formation of a surface-bound hydroperoxy species is the rate-determining step in photocatalytic oxygen evolution.

AB - The kinetics of electron transfer and oxygen evolution at citrate-stabilized IrO x·nH 2O colloids were studied by time-resolved UV-visible spectrosopy and by steady-state photolysis of [Ru(bpy) 3] 2+ (bpy = 2,2′-bipyridyl) and persulfate in a hexafluorosilicate/bicarbonate buffer. Time-resolved studies of the reaction of [Ru(bpy) 3] 3+ with these colloids show an initial fast electron transfer, corresponding to oxidation of Ir(III) to Ir(IV). Further oxidation of surface Ir atoms occurs concomitantly with oxygen evolution with a second-order rate constant of 1.3 × 10 6 M -1 s -1. Both the time-resolved reduction of [Ru(bpy) 3] +3 by IrO x·nH 2O and the photocatalytic oxygen evolution under non-light-limited photolysis conditions have a H/D kinetic isotope effect (KIE) of 1.0. This contrasts with significantly higher KIE values for oxygen evolution from molecular cis,cis-[(bpy) 2Ru-(OH 2)] 2O] 4+ and [(terpy)(H 2O)Mn III(O) 2(OH 2)terpy)] 3- water oxidation catalysts. This is consistent with the conclusion that, under the conditions of most photocatalytic experiments (∼10 -4 M [Ru(bpy) 3] 2+ concentration), electron transfer from the colloid to the oxidized sensitizer rather than formation of a surface-bound hydroperoxy species is the rate-determining step in photocatalytic oxygen evolution.

UR - http://www.scopus.com/inward/record.url?scp=7544245937&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=7544245937&partnerID=8YFLogxK

U2 - 10.1021/jp0480145

DO - 10.1021/jp0480145

M3 - Article

AN - SCOPUS:7544245937

SN - 1089-5639

VL - 108

SP - 9115

EP - 9119

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

IS - 42

ER -

Kinetics of electron transfer and oxygen evolution in the reaction of [Ru(bpy) ₃] ³⁺ with colloidal iridium oxide

Abstract

All Science Journal Classification (ASJC) codes

Access to Document

Other files and links

Fingerprint

Cite this