Redox processes at metal oxide/solution interfaces are often described as outer-sphere electron transfer reactions. However, this presentation will show that they are often proton-coupled electron transfer (PCET) processes. For instance, comparing the reactivity of photoreduced TiO2 with ET and PCET oxidants show that proton transfer accompanies electron transfer to or from the TiO2. The electrochemical oxidation of Ni(OH)2 thin films proceeds by PCET to give NiOOH. For such PCET processes, the relevant energy parameter is the hydrogen-atom affinity of the material, not electronic energies such as Fermi levels or band energies. Measurements of such O–H bond dissociation free energies for colloidal CeO2-x and other oxide NCs will be described. These studies are building an understanding of the stoichiometry and energetics of oxide / solution interfaces that will be valuable in the use of these materials in energy conversion processes.

Proton-coupled electron transfer reactions at metal oxide/solution interfaces

2019 Spring National Meeting

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