Raman scattering detection of cobalt(ii) ions based on their specific etching effect on leaf-like poly(p-phenylenediamine) microcrystals

Abstract

We report a simple Raman scattering method for the sensitive and selective detection of cobalt(II) ions using the combination of leaf-like poly(p-phenylenediamine) (PpPD) microcrystals and Ag nanoparticles (AgNPs) as the signal provider. The AgNPs provide much greater Raman scattering enhancement to the PpPD microparticles. However, it was found that the PpPD microparticles can be selectively etched and degraded by cobalt(II) ions, resulting in a decrease in Raman signal intensity. Therefore, the combination of PpPD microparticles and AgNPs provides an excellent Raman scattering signal readout platform for sensitive and specific cobalt(II) detection, and the decrease in Raman signal intensity is found to be proportional to the logarithm of cobalt(II) concentration over the range of 0.3–50 μM with a detection limit (3σ) of 20 nM.