Direct metal substitution of electropolymerized ferriprotoporphyrin: A simple electrode-modification process for developing electrocatalytic materials

A simple approach for expanding metalloporphyrins as electrocatalytic materials is introduced. This new method involves the direct electropolymerization of an electrically conducting layer of ferriprotoporphyrin followed by a metal-substitution reaction executed by soaking the electrode in an aqueous metal-salt solution. This process exchanges the iron center of the surface-bound protoporphyrin with the metal ion of the salt solution. X-ray photoelectron spectroscopy and electrochemical methods confirm that this new metal is incorporated into the surface-bound porphyrin structure and alters the electrochemical properties of the electrode. This simple electrode modification process may expand the use of metalloporphyrins for electrocatalytic applications.