Electrochemical Surface-Enhanced Raman Spectroscopy of acetaminophen: Adsorption dynamics and charge transfer mechanism

Electrochemical Surface-Enhanced Raman Spectroscopy (EC-SERS) enables detailed study of molecular adsorption and charge transfer at metal surfaces. This work investigates acetaminophen (AAP) adsorption on a roughened copper electrode using EC-SERS combined with cyclic voltammetry (CV). CV confirms AAP’s electrochemical stability within −1000 to 0 mV, allowing analysis of adsorption without redox interference. AAP rapidly adsorbs within eight CV cycles (∼13 min), forming stable surface complexes primarily through amine group interactions. Desorption is slower, indicated by gradual changes in electrochemical current and Raman signal during reverse scans. The highest SERS enhancement occurs at −600 mV, where optimal charge transfer and molecular orientation maximize signal intensity. Density functional theory calculations support experimental findings, confirming the formation of metal-molecule “complexes” consistent with observed vibrational modes. The study highlights the influence of applied potential on adsorption/desorption dynamics and demonstrates copper’s promise as an affordable EC-SERS substrate. Despite lower enhancement compared to noble metals, copper’s biocompatibility and surface versatility make it suitable for biomedical and environmental sensing applications. These insights contribute to the advancement of electrochemical sensors based on EC-SERS for pharmaceutical and bioanalytical uses.