Distinguishing homogeneous from heterogeneous catalysis in electrode-driven water oxidation with molecular iridium complexes

Nathan D. Schley, James D. Blakemore, Navaneetha K. Subbaiyan, Christopher D. Incarvito, Francis Dsouza, Robert H. Crabtree, Gary W Brudvig

Research output: Contribution to journalArticle

217 Citations (Scopus)

Abstract

Molecular water-oxidation catalysts can deactivate by side reactions or decompose to secondary materials over time due to the harsh, oxidizing conditions required to drive oxygen evolution. Distinguishing electrode surface-bound heterogeneous catalysts (such as iridium oxide) from homogeneous molecular catalysts is often difficult. Using an electrochemical quartz crystal nanobalance (EQCN), we report a method for probing electrodeposition of metal oxide materials from molecular precursors. Using the previously reported [CpIr(H2O)3]2+ complex, we monitor deposition of a heterogeneous water oxidation catalyst by measuring the electrode mass in real time with piezoelectric gravimetry. Conversely, we do not observe deposition for homogeneous catalysts, such as the water-soluble complex CpIr(pyr-CMe2O)X reported in this work. Rotating ring-disk electrode electrochemistry and Clark-type electrode studies show that this complex is a catalyst for water oxidation with oxygen produced as the product. For the heterogeneous, surface-attached material generated from [CpIr(H 2O)3]2+, we can estimate the percentage of electroactive metal centers in the surface layer. We monitor electrode composition dynamically during catalytic turnover, providing new information on catalytic performance. Together, these data suggest that EQCN can directly probe the homogeneity of molecular water-oxidation catalysts over short times.

Original languageEnglish
Pages (from-to)10473-10481
Number of pages9
JournalJournal of the American Chemical Society
Volume133
Issue number27
DOIs
Publication statusPublished - Jul 13 2011

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Iridium
Catalysis
Electrodes
Oxidation
Catalysts
Water
Quartz
Metals
Electroplating
Oxygen
Electrochemistry
Molecular Probes
Oxides
Crystals
Gravimetric analysis
Electrodeposition
Chemical analysis

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Distinguishing homogeneous from heterogeneous catalysis in electrode-driven water oxidation with molecular iridium complexes. / Schley, Nathan D.; Blakemore, James D.; Subbaiyan, Navaneetha K.; Incarvito, Christopher D.; Dsouza, Francis; Crabtree, Robert H.; Brudvig, Gary W.

In: Journal of the American Chemical Society, Vol. 133, No. 27, 13.07.2011, p. 10473-10481.

Research output: Contribution to journalArticle

Schley, Nathan D. ; Blakemore, James D. ; Subbaiyan, Navaneetha K. ; Incarvito, Christopher D. ; Dsouza, Francis ; Crabtree, Robert H. ; Brudvig, Gary W. / Distinguishing homogeneous from heterogeneous catalysis in electrode-driven water oxidation with molecular iridium complexes. In: Journal of the American Chemical Society. 2011 ; Vol. 133, No. 27. pp. 10473-10481.
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