期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 108, 期 52, 页码 E1461-E1469出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1115769108
关键词
concerted electron-proton transfer; metal oxide electrode; surface modification; electrocatalysis; spectroelectrochemistry
资金
- Army Research Office [W911NF-09-1-0426]
- University of North Carolina Energy Frontier Research Center (EFRC) Solar Fuels and Next Generation Photovoltaics
- US Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-SC0001011]
- Center for Catalytic Hydrocarbon Functionalization
- US Department of Energy at the University of Virginia [DE-SC0001298]
- U.S. Department of Energy (DOE) [DE-SC0001298] Funding Source: U.S. Department of Energy (DOE)
In single site water or hydrocarbon oxidation catalysis with polypyridyl Ru complexes such as [Ru(II)(Mebimpy)(bpy)(H(2)O)](2+) [where bpy is 2,2'-bipyridine, and Mebimpy is 2,6-bis(1-methylbenzimidazol-2-yl)pyridine] 2, or its surface-bound analog [Ru(II)(Mebimpy) (4,4'-bis-methlylenephosphonato-2,2'-bipyridine)(OH(2))](2+) 2-PO(3)H(2), accessing the reactive states, Ru(V)=O(3+)/Ru(IV)=O(2+), at the electrode interface is typically rate limiting. The higher oxidation states are accessible by proton-coupled electron transfer oxidation of aqua precursors, but access at inert electrodes is kinetically inhibited. The inhibition arises from stepwise mechanisms which impose high energy barriers for 1e(-) intermediates. Oxidation of the Ru(III)-OH(2+) or Ru(III)-OH(2)(3+) forms of 2-PO(3)H(2) to Ru(IV)=O(2+) on planar fluoride-doped SnO(2) electrode and in nanostructured films of Sn(IV)-doped In(2)O(3) and TiO(2) has been investigated with a focus on identifying microscopic phenomena. The results provide direct evidence for important roles for the nature of the electrode, temperature, surface coverage, added buffer base, pH, solvent, and solvent H(2)O/D(2)O isotope effects. In the nonaqueous solvent, propylene carbonate, there is evidence for a role for surface-bound phosphonate groups as proton acceptors.
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