The Electrochemical Deposition of Sol-Gels for Spectroelectrochemical Sensing

Abstract

Spectroelectrochemical sensing provides three simultaneous modes of enhanced selectivity: chemically selective films, spectroscopy, and electrochemistry. Chemically selective sol-gels films are particularly useful in applications demanding optical transparency. Sol-gels have traditionally been deposited by means of spin or dip coating, limiting their spatial resolution. This work utilizes indium-tin oxide optically transparent electrodes for electrochemical deposition of sol-gel films. Functionalization can be tailored for chemical selectivity and is deposited locally where potential is applied to catalyze sol-gel formation. The system studied in this work provides tri-modal selectivity by means of charge exclusion, electrochemical activity, and/or optical properties of Ru(bpy)₃²⁺. Deposition parameters were optimized for precursor concentration and film thickness. A flow cell system was designed to test the diffusive effects of Ru(bpy)₃²⁺ and for simultaneous collection of electrochemical and optical data. Spectroelectrochemical sensing can be applied for the indirect detection of trace Cr⁶⁺.