Monitoring SEIRAS on a Graphitic Electrode for Surface-Sensitive Electrochemistry: Real-Time Electrografting

Area of Science:

• Electrochemistry
• Materials Science
• Spectroscopy

Background:

• Graphitic materials are crucial in electrochemistry, necessitating methods to study their interfacial behavior.
• Spectroelectrochemistry, particularly Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS), probes molecular dynamics at electrode/electrolyte interfaces.
• Existing SEIRAS techniques are limited, often requiring plasmonic metals and lacking convenient substrates for carbon-based studies.

Purpose of the Study:

• To develop a novel hybrid graphene-on-gold substrate for SEIRAS.
• To demonstrate the substrate's capability in monitoring electrografting processes on graphitic surfaces in real-time.
• To overcome limitations of current SEIRAS techniques for carbon electrode investigations.

Main Methods:

• Fabrication of a hybrid graphene-on-gold substrate using a roughened gold-sputtered internal reflection element (IRE).
• Application of Attenuated Total Reflectance (ATR)-SEIRAS to monitor electrografting.
• Characterization of grafted molecules (4-amino-TEMPO and 4-nitrobenzene diazonium) using cyclic voltammetry and ATR-SEIRAS.

Main Results:

• Successfully monitored the real-time electrografting of 4-amino-TEMPO and 4-nitrobenzene diazonium on the graphene-gold substrate.
• Identified characteristic spectral signatures for both grafted molecules using ATR-SEIRAS.
• Demonstrated superior stability and resolution for grafting on the hybrid substrate compared to bare graphene or gold.

Conclusions:

• The developed graphene-gold IRE substrate significantly expands the applicability of SEIRAS for studying graphitic electrodes.
• This approach enables unambiguous, real-time detection of surface processes on carbon electrodes.
• The findings open new avenues for spectroelectrochemical investigations in sensing, energy storage, electrocatalysis, and environmental science.