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 language | English |
|---|---|
| Pages (from-to) | 10473-10481 |
| Number of pages | 9 |
| Journal | Journal of the American Chemical Society |
| Volume | 133 |
| Issue number | 27 |
| DOIs | |
| Publication status | Published - Jul 13 2011 |
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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 journal › Article
}
TY - JOUR
T1 - Distinguishing homogeneous from heterogeneous catalysis in electrode-driven water oxidation with molecular iridium complexes
AU - Schley, Nathan D.
AU - Blakemore, James D.
AU - Subbaiyan, Navaneetha K.
AU - Incarvito, Christopher D.
AU - Dsouza, Francis
AU - Crabtree, Robert H.
AU - Brudvig, Gary W
PY - 2011/7/13
Y1 - 2011/7/13
N2 - 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.
AB - 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.
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U2 - 10.1021/ja2004522
DO - 10.1021/ja2004522
M3 - Article
VL - 133
SP - 10473
EP - 10481
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 27
ER -