In search of the inverted region: Chromophore-based driving force dependence of interfacial electron transfer reactivity at the nanocrystalline titanium dioxide semiconductor/solution interface

Intentional variations of the driving force for back electron transfer from titanium dioxide to a surface-bound redox couple, through synthetic alteration of the couple's formal potential, show that the reaction takes place in the Marcus normal region. Variable-temperature rate measurements show that the back electron transfer is thermally activated, with the activation barrier decreasing with increasing driving force, as expected for a normal region process.