Surface modification of silver nanofilms for improved perchlorate detection by surface-enhanced Raman scattering

► Cysteamine SAMs modified Ag nanofilms were developed for robust ClO4- SERS detection. ► High affinity of cysteamine for ClO4- effectively enriched low concentration ClO4-. ► A detection limit of 5 μg L−1 was obtained for aqueous ClO4- without need for drying. ► Calibration curves were fabricated to demonstrate quantitative SERS analyses of ClO4-. ► The Ag nanofilms were proved to be stable and could be regenerated and reused.