Work

Unveiling the Neglected Role of Silver Ions’ Leaching for Recovered Functionality of Carboxylate SAMs on Ag

Year: 2025

Type: article

Abstract: The full release of surface-enhanced Raman spectroscopy (SERS) ability relies on modification of the substrates surface. However, chemical modifications of the widely used silver substrates have, in some cases, led to anomalous behaviors that are difficult to explain. These issues limit the widespread application of silver as a SERS substrate material. In this study, the anomaly of carboxyl-containing self-assembled monolayers (SAMs) on silver substrates for SERS was investigated, focusing on the interference caused by silver ions’ leaching during surface modification. Using 4-mercaptobenzoic acid (4-MBA) as a model molecule, carboxylates grafted through SAMs were found to bound with Ag+ ions, which significantly altering their SERS response. The release of Ag+ from silver surface also leads to severe multilayer adsorption of carboxyl molecules. To address this issue, a deoxygenation treatment was introduced, through which the silver-carboxylate SAMs constructed showed a stable and accurate response to varying pH levels and successfully detected 30 ppm gaseous acetic acid. This work provides a clarifying perspective towards the underlying mechanisms of Ag+ interference and developed a method for enhancing the reliability of silver-based SERS sensors, paving the way for their broader application in molecular sensing.

Source: Analytical Chemistry

DOI: 10.1021/acs.analchem.5c03988