Confinement-Controlled Electrochemistry in Imprinted Nanoreactors

Abstract This study establishes a bottom-up strategy for fabricating electrochemically addressable nanocavities with high structural precision and reproducibility by templating silica sol–gel thin films with polystyrene nanoparticles (PS NPs) on conductive electrodes. Controlled PS NP adsorption, sol–gel encapsulation, and selective NP dissolution yield hemispherical cavities that are structurally uniform and spatially isolated and expose only a defined region of the underlying conductive substrate with a radius of roughly 5 nm. Correlative spectroscopic and microscopic analyses confirm the preservation of matrix integrity, faithful replication of NP geometry down to 100 nm, and complete removal of PS, establishing clean, well-defined nanoconfinement. The sol–gel matrix effectively passivates the macroscopic surface, while the cavity bases act as individual nanoelectrodes that can be chemically functionalized and exploited as embedded nanoreactors. Ensemble electrochemical measurements thus selectively probe confined sites, enabling controlled studies of nanocavity-confined redox processes and site-selective metal growth and providing a versatile platform for future single-nanocavity electrochemistry and easily manufactured nanoconfined sensing architectures. A scanning electrochemical microscope equipped with a nanoelectrode tip was used to obtain feedback and generation/collection mode images of individual cavities and demonstrate the potential utility of this technique for probing electrochemical processes in confined spaces.