Bifunctional Nanostructures for Spatial and Temporal Control of Electron Transfer Reactions

Monday, March 08, 2021: 2:40 PM - 3:15 PM

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Description

Understanding the behavior of chemical reactions in confined volumes is important in applications ranging from water purification to healthcare devices. Especially relevant are wetting and dewetting phenomena which can be switched by external stimuli, such as light, electric fields, and the presence of chemical modulators, such as H+. These behaviors can be exploited for electrochemical processing by voltage-directed ion transport in nanochannels contained within nanopore electrode arrays (NEA) in which access to the working electrode is actively controlled by electric field-induced wetting/dewetting phenomena in nanoscale channels. In one scheme, multiple electrodes are present in each nanopore, and electrochemical transistor operation is obtained when small, defect-mediated channels are opened in thin dielectric films covering one of the electrodes. These defect channels exhibit voltage-driven wetting that mediates the mass transport of redox species to/from the electrode. In another scheme, the dielectric film is constructed from a pH- and field-dependent block copolymer membrane, which is placed over the NEA to actively control access of redox species to the NEA nanopore. Together these approaches make it possible to control access of redox species to the NEA electrodes thereby conferring great advantages in sensitivity and selectivity in electroanalysis and electrochemical processing.