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Title: Photoinduced Stepwise Oxidative Activation of a Chromophore-Catalyst Assembly on TiO2

Abstract

To probe light-induced redox equivalent separation and accumulation, we prepared ruthenium polypyridyl molecular assembly [(dcb)₂Ru(bpy-Mebim₂py)Ru(bpy)(OH₂)] 4+ (Ru a II–Ru b II–OH₂) with Ru a as light-harvesting chromophore and Ru b as water oxidation catalyst (dcb = 4,4'-dicarboxylic acid-2,2'-bipyridine; bpy-Mebim₂py = 2,2'-(4-methyl-[2,2':4',4"-terpyridine]-2",6"-diyl)bis(1-methyl-1H-benzo[d]imidazole); bpy = 2,2'-bipyridine). When bound to TiO₂ in nanoparticle films, it undergoes MLCT excitation, electron injection, and oxidation of the remote -Ru b II-OH₂ site to give TiO₂(e⁻)-Ru a II-Ru b III–OH₂ 3+ as a redox-separated transient. The oxidized assembly, TiO₂-Ru a II-Ru b III-OH₂³⁺, similarly undergoes excitation and electron injection to give TiO₂(e⁻)-Ru a II-Ru b IV=O²⁺, with Ru b IV=O²⁺ a known water oxidation catalyst precursor. Injection efficiencies for both forms of the assembly are lower than those for [Ru(bpy)₂(4,4'-(PO₃H₂)₂bpy)]²⁺ bound to TiO₂ (TiO₂-Ru²⁺), whereas the rates of back electron transfer, TiO₂(e⁻) → Ru b III-OH₂³⁺ and TiO₂(e⁻) → Ru b IV=O²⁺, are significantly decreased compared with TiO₂(e⁻) → Ru³⁺ back electron transfer.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Univ. of North Carolina, Chapel Hill, NC (United States)
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC); Center for Catalytic Hydrocarbon Functionalization (CCHF)
Sponsoring Org.:
USDOE
OSTI Identifier:
1065984
DOE Contract Number:  
SC0001298
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry Letters
Additional Journal Information:
Journal Volume: 2; Journal Issue: 14; Related Information: CCHF partners with University of Virginia (lead); Brigham Young University; California Institute of Technology; Colorado School of Mines; University of Maryland; University of North Carolina, Chapel Hill; University of North Texas; Princeton University; The Scripps Research Institute; Yale University; Journal ID: ISSN 1948-7185
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 14 SOLAR ENERGY; catalysis (homogeneous), catalysis (heterogeneous), bio-inspired, hydrogen and fuel cells, materials and chemistry by design, synthesis (novel materials)

Citation Formats

Song, Wenjing, Glasson, Christopher R. K., Luo, Hanlin, Hanson, Kenneth, Brennaman, M. Kyle, Concepcion, Javier J., and Meyer, Thomas J. Photoinduced Stepwise Oxidative Activation of a Chromophore-Catalyst Assembly on TiO2. United States: N. p., 2011. Web. doi:10.1021/jz200773r.
Song, Wenjing, Glasson, Christopher R. K., Luo, Hanlin, Hanson, Kenneth, Brennaman, M. Kyle, Concepcion, Javier J., & Meyer, Thomas J. Photoinduced Stepwise Oxidative Activation of a Chromophore-Catalyst Assembly on TiO2. United States. doi:10.1021/jz200773r.
Song, Wenjing, Glasson, Christopher R. K., Luo, Hanlin, Hanson, Kenneth, Brennaman, M. Kyle, Concepcion, Javier J., and Meyer, Thomas J. Thu . "Photoinduced Stepwise Oxidative Activation of a Chromophore-Catalyst Assembly on TiO2". United States. doi:10.1021/jz200773r.
@article{osti_1065984,
title = {Photoinduced Stepwise Oxidative Activation of a Chromophore-Catalyst Assembly on TiO2},
author = {Song, Wenjing and Glasson, Christopher R. K. and Luo, Hanlin and Hanson, Kenneth and Brennaman, M. Kyle and Concepcion, Javier J. and Meyer, Thomas J.},
abstractNote = {To probe light-induced redox equivalent separation and accumulation, we prepared ruthenium polypyridyl molecular assembly [(dcb)₂Ru(bpy-Mebim₂py)Ru(bpy)(OH₂)]4+ (RuaII–RubII–OH₂) with Rua as light-harvesting chromophore and Rub as water oxidation catalyst (dcb = 4,4'-dicarboxylic acid-2,2'-bipyridine; bpy-Mebim₂py = 2,2'-(4-methyl-[2,2':4',4"-terpyridine]-2",6"-diyl)bis(1-methyl-1H-benzo[d]imidazole); bpy = 2,2'-bipyridine). When bound to TiO₂ in nanoparticle films, it undergoes MLCT excitation, electron injection, and oxidation of the remote -RubII-OH₂ site to give TiO₂(e⁻)-RuaII-RubIII–OH₂3+ as a redox-separated transient. The oxidized assembly, TiO₂-RuaII-RubIII-OH₂³⁺, similarly undergoes excitation and electron injection to give TiO₂(e⁻)-RuaII-RubIV=O²⁺, with RubIV=O²⁺ a known water oxidation catalyst precursor. Injection efficiencies for both forms of the assembly are lower than those for [Ru(bpy)₂(4,4'-(PO₃H₂)₂bpy)]²⁺ bound to TiO₂ (TiO₂-Ru²⁺), whereas the rates of back electron transfer, TiO₂(e⁻) → RubIII-OH₂³⁺ and TiO₂(e⁻) → RubIV=O²⁺, are significantly decreased compared with TiO₂(e⁻) → Ru³⁺ back electron transfer.},
doi = {10.1021/jz200773r},
journal = {Journal of Physical Chemistry Letters},
issn = {1948-7185},
number = 14,
volume = 2,
place = {United States},
year = {2011},
month = {7}
}