Harnessing Electric Fields at the Air-Water Interface: The Case of Soap Films

Interfacial electric-fields have since long been implicated in chemical reactivity, assuming particular relevance in, for instance, natural enzymatic systems or for key reactions influencing atmospheric chemistry. Reports documenting fantastic rate enhancement at the interface in artificial systems are also extant, though direct mechanistic insight into how the interfacial electric field plays a role is lacking. In this perspective, we use soap films as model systems and test for the impact of the interfacial electric field on rates of bimolecular electron transfer, using time-resolved fluorescence spectroscopy. Surprisingly, a substantial acceleration in rates is not seen.  We encapsulate lessons learned from both experiment and theory, and highlight potentially overlooked parameters and challenges vis-à-vis harnessing the interfacial field in particular – and the interface generally – for affecting useful chemistry. Indeed, attribution of remarkable reactivity at the interface to the asymmetric electric field must be treated with due caution.