Synergy Mechanisms in Laser-Induced Graphene between Surface-Enhanced Raman Spectroscopy and Electrochemical Methods for Enhanced Dual Sensing

The development of chemical sensors with selectivity and sensitivity to detect contaminants is challenging, especially in the presence of interferents possessing similar molecular structures. Electrochemical (EC) and Surface-enhanced Raman Spectroscopy (SERS) sensors are widely used, albeit with their disadvantages. However, integration of the two methods into a single platform can potentially overcome their disadvantages. Until now, the majority of the research has focused on EC-supported SERS detection, thereby not exploiting the entire capabilities of EC-SERS. Laser-induced graphene (LIG) technology, a cost-effective and one-step method to produce graphene electrodes, is widely implemented for EC sensors but to a very low extent for SERS. Herein, we aim to perform a comprehensive study on the synergy of EC-SERS methods by developing a dual-sensor platform for 4-nitrophenol (4-NP) detection on LIG embedded with electrodeposited plasmonic silver nanostructures. EC roughening and electrode polarization led to a significant amplification of the SERS response. The selectivity issues with EC methods were overcome through sequential SERS-EC-SERS measurements making it possible to detect 4-NP in solutions containing similar molecules, which was a critical issue reported before. Both methods demonstrated a good capability to detect and quantify 4-NP, exhibiting distinct response modalities. This research establishes a practical approach for leveraging EC and SERS synergy to achieve high analytical performance in detecting molecules with high selectivity in complex chemical environments.