Mn₁₂O₁₂(O₂CC₆H₂(OH)₃)₁₆(H₂O)₄ as a Soluble Electrocatalyst for Water-Oxidation

A promising approach in the search of renewable and alternative energy is the development of an artificial photosynthetic system by mimicking nature, for the production of hydrogen from water by the water splitting reaction. Water splitting is a two-step process, in which water is first oxidized to yield oxygen; and later protons are reduced to produce hydrogen. The primary bottleneck of the process is the development of an efficient water oxidation electro-catalyst. Water oxidation is catalyzed in nature by the OEC, the oxygen-evolving center of photosystem II, a robust high oxidation state Mn₄CaOx cluster; producing O₂, protons and electrons. Our research goal is to design a molecular catalyst for electrochemical water oxidation, inspired by the natural OEC of PSII. To this aim we synthesize "Mn₁₂TH" [Mn₁₂O₁₂(O₂CC₆H₂(OH)₃)₁₆(H₂O)₄], a water soluble manganese-oxo cluster. The cluster is composed of catalytic inorganic core of poly-nuclear high-oxidation state manganese atoms, and an outer organic shell of sixteen 3,4,5-trihydroxybenzoic acid ligands. The resulting cluster is characterized and its electrocatalytic performance is tested for efficient water oxidation.