Water oxidation is a critical step in water splitting to make hydrogen fuel. We report the solution synthesis, structural/compositional characterization, and oxygen-evolution-reaction (OER) electrocatalytic properties of ~2-3 nm-thick films of NiOx, CoOx, NiyCo1-yOx, Ni0.9Fe0.1Ox, IrOx, MnOx, and FeOx. The thin-film geometry enables the use of quartz-crystal microgravimetry, voltammetry, and steady-state Tafel measurements to study the intrinsic activity and electrochemical properties of the films. Ni0.9Fe0.1Ox was the most active catalyst which is attributed to the in-situ formation of layered Ni0.9Fe0.1OOH oxyhydroxide species with nearly every Ni atom electrochemically active.Towards the goal of incorporating these catalysts with semiconductor photoelectrodes for solar water splitting we use in-situ spectroelectrochemistry to quantify the optical properties of the catalysts. We report a simple model of composite semiconductor-catalyst photoelectrodes that accounts for parasitic optical absorption in the catalysts and calculate a figure-of-merit as a function of thickness to inform future photoelectrode design.

Thin film electrocatalysts for oxygen evolution

245th National Meeting (2013)

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