The second lecture will introduce contemporary electrocatalysis as the fundamental study of electrode reactions where the kinetics depends strongly on the physicochemical properties of electrochemical interfaces; encompassing both the nature of electrode materials and the rarely discussed structure of the double layer. At least for judiciously chosen systems, a key fundamental issue addressed in this presentation is the degree to which the fundamental understanding of the structure/nature of electrochemical interface (that is introduced in the first lecture) determines the efficiency of the water cycle - that is controlled by the making and breaking of H-H, H-O and O-O bonds and the associated production of electrons (electricity) andH2Oin fuel cells; or on the utilization of electrons for theH2Osplitting reaction to regenerateH2 and O2 in electrolyzers.
For decades, the design of catalysts for the water cycle has been guided by energetic factors, whereby the binding energy of intermediates to elusive "active sites" is assumed to control the reaction kinetics. This presentation will go beyond a singular "kinetics-designing" principle, providing atomic-/molecular-level insights that will open some new avenues in designing novel electrochemical interfaces; in particular, for improving the kinetics of the hydrogen evolution (HER) and hydrogen oxidation (HOR) reactions. Key correlations will be discussed, including structure-function relationships, the role of pH values, the role of temperature and the nature of adsorbed spectator species that are formed either from adsorption of components present in supporting electrolytes or formed during the course of the reaction. We also show how the nature of electrochemical interfaces controls the reaction kinetics.
The second archetypical example will include discussions about the kinetics of the CO oxidation reaction, which is one key molecule that determines the efficiency of the carbon cycle - that is in general basedeither on C-H and C-O bond making/breaking events and the concomitant production ofCO2 in fuel cells or on the reduction ofCO2 to produce hydrocarbon fuels and O2 in electrolyzers. At the end of the second we provide atomic-/molecular-level insights needed to simultaneously control activity and stability of electrode materials such as metals, oxides and sulfides. Indeed this will be used as a prelude for the third lecture which will be focusing on the oxygen electrochemistry.
