Fundamentals and Applications in Solution-phase Electrochemistry and Electrocatalysis

A simple treatment of the fundamentals of solution-phase voltammetry is followed by six examples of porphyrinoids highlighting how structural changes of the redox species influence formal reduction potentials. Electronic communication among different molecular groups is demonstrated, and it is shown how the correct solvent and supporting electrolyte choice may result in observing 17 of a possible 18 redox processes in a cadmium triple-decker phthalocyanine. The difference between outer- and inner-sphere electron transfer processes is used to introduce adsorption effects of redox species on electrodes. This forms the bases of electrocatalysis, and a short theoretical introduction to electrocatalysis is presented. The reader is then eased into electrocatalysis concepts through a discussion of electrocatalyzed alcohol oxidation and sulfite sensors with adsorbed porphyrin polymers. Covalent binding or adsorption to the electrode or solution-phase electrocatalysts are demonstrated. Electrocatalysis in fuel production or energy storage systems concludes this chapter. CO2 reduction by an Fe0 porphyrin, an octaalkoxylated Co phthalocyanine, which aggregates less, and covalent– and metal–organic framework complexes of Co porphyrinoids, are considered. Hydrogen evolution by Ni porphyrins, oxygen reduction to either H2O or H2O2, and H2O oxidation to O2 utilizing carefully chosen porphyrinoids are other reactions that are discussed.