Potential Routes and Mitigation Strategies for Contamination in Interfacial Specific Infrared Spectroelectrochemical Studies

Attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) is a powerful tool for probing the electrochemical interface; however, inconsistencies in reported spectroscopic observations persist. In this work, we identify potential sources of contamination in ATR-SEIRAS using CO as a probe molecule by varying the electrolyte purity, counter electrode (CE), and anolyte/catholyte separator. We show that only a linearly bound CO near 2050-2100 cm(-1) is observed in clean experiments, whereas the use of low-purity electrolytes and Pt CEs leads to additional bands near 1800-1950 and 1920-2020 cm(-1), respectively, which are commonly assigned to bridge-bonded CO in the previous literature. These observations highlight the extreme sensitivity of ATR-SEIRAS and the importance of avoiding contaminants which lead to additional spectroscopic features.