A multimodal optical and electrochemical device for monitoring surface reactions: redox active surfaces in porous silicon Rugate filters

Abstract

Herein, mesoporous silicon (PSi) is configured as a single sensing device that has dual readouts; as a photonic crystal sensor in a Rugate filter configuration, and as a high surface area porous electrode. The as-prepared PSi is chemically modified to provide it with stability in aqueous media and to allow for the subsequent coupling of chemical species, such as via Cu(I)-catalyzed cycloaddition reactions between 1-alkynes and azides (“click” reactions). The utility of the bimodal capabilities of the PSi sensor for monitoring surface coupling procedures is demonstrated by the covalent coupling of a ferrocene derivative, as well as by demonstrating ligand–exchange reactions (LER) at the PSi surface. Both types of reactions were monitored through optical reflectivity measurements, as well as electrochemically via the oxidation/reduction of the surface tethered redox species.