Photochemical synthesis of Silver Nanoprisms via green LEDs irradiation and evaluation of SERS activity

Silver nanoprisms (AgNPrs) are promising candidates for surface-enhanced Raman scattering (SERS) due to their strong localized surface plasmon resonance (LSPR) and sharp-tip geometry. In this study, AgNPrs were synthesized through a photochemical method by irradiating spherical silver nanoparticle seeds with 10W green LEDs (520 ± 20 nm) for various durations up to 72 hours. The growth mechanism was investigated through UV–Vis spectroscopy, FE-SEM, and TEM analyses, confirming the gradual transformation of spherical seeds into AgNPrs. Optimal conversion was observed after 72 hours of irradiation, producing well-defined AgNPrs with an average size of 78 nm. The SERS activity of the AgNPrs was evaluated using 4-mercaptobenzoic acid (4-MBA) as a probe molecule. Compared to spherical AgNPs, AgNPrs exhibited a significantly higher SERS enhancement factor (EF), calculated as 1.15 × 10⁶, enabling detection limits down to 10⁻⁹ M. These findings demonstrate that green LED-mediated synthesis provides a simple, environmentally friendly route to fabricate high-yield AgNPrs with superior SERS capabilities, suitable for ultrasensitive chemical and biological sensing applications.