The electrocatalytic oxidation of water is a challenging step towards the production of hydrogen as an alternative fuel. In nature, water oxidation is catalysed by a high oxidation state Mn4CaO x cluster. The corresponding industrial development of manganese catalysts for water oxidation is very attractive due to the low cost of this metal. A few manganese complexes have been previously explored as water oxidation catalysts using various chemical oxidants in homogeneous and heterogeneous systems. Efficient electrochemical water oxidation catalysed by a soluble manganese-oxo cluster, however, has not been achieved. Here, we report the synthesis and characterization of [Mn12O12(O2CC6H3(OH)2)16(H2O)4] (Mn12DH), a unique example within this class of compounds in being both highly soluble and stable in water. We demonstrate that Mn12DH, which is readily prepared from cheap and environmentally benign starting materials, is a stable homogeneous water oxidation electrocatalyst operating at pH 6 with an exceptionally low overpotential of only 334 mV.
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This research was funded by the Solar Fuels Israel Center of Research Excellence (I-CORE) of the Israeli Science Foundation (ISF), grant number 2018762, and supported by the Grand Energy Technion Program. It was also funded by the USA National Science Foundation under grant CHE-1410394. We thank C. di Giovanni for the CV measurements of Mn 12 Ac in the glove box and for Fig. 2a. G.M. is grateful to A. Llobet at ICIQ, Tarragona, Spain, for the opportunity to work in his laboratories in order to study oxygen measurement techniques and gain additional knowledge in electrochemistry.
The authors declare no competing financial interests.
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Maayan, G., Gluz, N. & Christou, G. A bioinspired soluble manganese cluster as a water oxidation electrocatalyst with low overpotential. Nat Catal 1, 48–54 (2018) doi:10.1038/s41929-017-0004-2
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