Bimetallic catalysts provide the possibility of enhanced catalytic activity, selectivity and increased stability compared to their monometallic analogues. Water splitting (conversion of water into its basic components; dioxygen (water oxidation) and dihydrogen (water reduction)) is vital because hydrogen gas (H2) which is regarded as one of the cleanest sources of renewable energy, can be obtained from water. Due to the high energetic cost of water splitting, it is necessary that robust and efficient catalysts be developed for water reduction and water oxidation. We hypothesize that; (i) binuclear complexes of some first-row transition metals act as catalysts capable of oxidizing water, releasing electrons for the transformation of solar energy to chemical energy. (ii) Bimetallic species that display cooperativity (two metal centers working concurrently) among metals will lead to efficient conversion of protons to H2. This research focuses on the development of binuclear cobalt, nickel, manganese, and iron catalysts with a 2,6-bis [(bis(2-pyridylmethyl) amino) methyl]-4-methylphenol ligand (HL1), for water reduction and water oxidation. To this end, the nickel and cobalt catalysts have been assessed for the presence and mechanisms of cooperation for water reduction whereas the manganese and iron catalysts have been assessed preliminarily for its ability to act as catalysts for water oxidation. From our findings, we have theoretically and experimentally proven that the bimetallic nickel catalyst exhibits no cooperativity while the bimetallic cobalt catalyst does show cooperativity.

Investigating bimetallic catalytic enhancement through water splitting

ACS Fall 2021

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