2-pyridyl-2-propanoate (pyalk) has been shown to be an effective ligand for homogeneous water oxidation catalysts (WOCs). The combination of high donor power, oxidation resistance, and strong binding allows pyalk to stabilize the high oxidation states necessary for water oxidation catalysis, resulting in several highly active iridium-pyalk WOCs. Given the recent interest in developing WOCs containing cheap and abundant metal centers, we have synthesized and characterized Cu(pyalk)2 for use as a water oxidation electrocatalyst. The copper(II) complex Cu(pyalk)2 is a robust homogeneous water-oxidation electrocatalyst under alkaline conditions with an overpotential of 520-580 mV. The catalyst displays a turnover frequency of ~0.7 s-1 at pH 12. Controlled potential electrolysis experiments over 12 h at 1.1 V vs. NHE resulted in the formation &gt;30 catalytic turnovers of O2 and only ~20% catalyst degradation. A structurally similar copper(II) picolinate complex was found to degrade to copper(II) hydroxide (Cu(OH)2) under the same conditions, demonstrating the effectiveness of pyalk as a ligand for homogeneous WOCs. The robustness of the catalyst under fairly harsh conditions and the catalyst's low overpotential further highlight the oxidation resistance and strong donor character of the pyalk ligand.

Electrocatalytic water oxidation by a copper(II) complex with an oxidation-resistant N,O-donor ligand

254th National Meeting (2017)

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