A Bioinspired Soluble Manganese Cluster as a Water-Oxidation Electrocatalyst with Low Overpotential

The electrocatalytic oxidation of water is an essential, yet a challenging step towards the production of hydrogen as an alternative fuel. In Nature, the oxidation of water into oxygen and protons is catalyzed by a high oxidation state Mn₄CaO_x cluster. The corresponding industrial development of high-valent manganese catalysts for water oxidation is very attractive due to the low cost of this metal. A few small nuclearity manganese complexes have been previously explored as water oxidation catalysts using various chemical oxidants in homogeneous and heterogeneous systems. Efficient electrochemical water oxidation catalyzed by a soluble manganese-oxo cluster, however, has not been achieved. Herein I will present 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. Extensive electrochemical research in our group 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, high turn-over number (TON) and about 80% Faradic efficiency.

Reference:

Galia Maayan*, Naama Gluz and George Christou “A Bioinspired Soluble Manganese Cluster as a Water-Oxidation Electrocatalyst with Low Overpotential”, Nat. Cat., DOI: 10.1038/s41929-017-0004-2.