Nonaqueous Electrochemical Surface-Enhanced Raman Spectroscopy (EC-SERS) Using Screen-Printed Electrodes

This work explores the development of nonaqueous electrochemical surface-enhanced Raman spectroscopy (EC-SERS) as a routine spectroelectrochemical characterization tool. The method has various benefits including the ability to explore molecular species with wide ranging solubility, it is relatively inexpensive, and it has potential for the analytical determination of nonpolar species. In this work, a classical SERS probe, 2,2′-bipyridine (22BPY), was studied as a proof-of-concept model system to establish the efficiency of reusable ceramic screen-printed electrode (SPE) sensors and to observe chemical effects associated with solvent. With the combined electrochemical and SERS effects, 22BPY was found to have an enhanced SERS signal of up to 4.6× in acetonitrile and 3.6× in methanol relative to the corresponding open-circuit potential (OCP) spectrum. Next, analytical targets including bisphenol A and bisphenol S (BPA and BPS) were studied using the EC-SERS system in methanol to further validate the method and showcase its potential for use as a method of probing and detecting low concentrations of Raman active compounds. Critical analysis of the method, opportunities for improvement, and potential avenues for future work are further discussed.