Surface plasmon-assisted catalytic reduction of p-nitrothiophenol for the detection of Fe²⁺ by surface-enhanced Raman...

Herein, we developed a concise, time-efficient, and high selective assay for detecting Fe²⁺ through its triggered surface plasmon-assisted reduction reaction of p-nitrothiophenol (PNTP) to p,p'-dimercaptoazobenzene (DMAB) on the surface of gold nanoparticles (AuNPs) based on surface-enhanced Raman scattering (SERS) spectroscopy. When Fe²⁺ was added to the PNTP-AuNPs system, the appearance of three characteristic peaks at 1142, 1392, and 1440 cm^-1 attributed to DMAB demonstrated that Fe²⁺ induced the catalytic coupling reaction of PNTP. The Raman intensity ratio of the peak at 1142 cm^-1 to the peak at 1336 cm^-1 and the concentration of Fe²⁺ presented a good linear response from 10 to 100 μM with a limit of detection (LOD) of 0.35 μM. More importantly, the entire detection process can be completed within 2 min and further successfully used for the detection of Fe²⁺ in river water.