Catalytic Activity of an Iron-Based Water Oxidation Catalyst: Substrate Effects of Graphitic Electrodes.

The synthesis, characterization, and electrochemical studies of the dinuclear complex (MeOH)Fe(Hbbpya)-μ-O-(Hbbpya)Fe(MeOH) () (with Hbbpya = -bis(2,2'-bipyrid-6-yl)amine) are described. With the help of online electrochemical mass spectrometry, the complex is demonstrated to be active as a water oxidation catalyst. Comparing the results obtained for different electrode materials shows a clear substrate influence of the electrode, as the complex shows a significantly lower catalytic overpotential on graphitic working electrodes in comparison to other electrode materials. Cyclic voltammetry experiments provide evidence that the structure of complex undergoes reversible changes under high-potential conditions, regenerating the original structure of complex upon returning to lower potentials. Results from electrochemical quartz crystal microbalance experiments rule out that catalysis proceeds via deposition of catalytically active material on the electrode surface.