Understanding the mechanisms of highly-active, earth-abundant water oxidation electrocatalysts can guide the development of advanced water-splitting devices that convert renewable electricity to clean fuels.<br/><br/>Unfortunately, catalytic intermediates are difficult to isolate and characterize because they tend to be extremely transient and present at low concentrations. A typical approach to this problem is to slow down turnover by limiting the availability of substrate. However, in cases where substrate and solvent are identical—such as in water oxidation—the solution can be more complex.<br/><br/>By dramatically limiting the availability of substrate (water and hydroxide) in nickel-iron catalyzed heterogeneous water oxidation, we have observed and characterized a high-valent iron intermediate. Orthogonal spectroscopies indicate that the intermediate contains iron in the rare 6+ oxidation state. This ferrate analog makes dioxygen upon addition of hydroxide and can be step-wise regenerated by anodic polarization.

Trapping an iron(VI) water-splitting intermediate in nonaqueous media

256th National Meeting (2018)

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