A novel plasmonic sensor for the detection of palladium based on facile in situ formation of silver nanoparticles in morin-formaldehyde/polyvinyl alcohol film.

The most important purpose in designing chemical sensors based on nanoparticles is the embedding of noble metal nanoparticles in a polymer film. These nano sensors have the advantage of allowing for tunable localized surface plasmon resonance (LSPR) peak positions due to the controllable nanoparticles size, shape and spacing. In this work, a new palladium sensor based on LSPR of silver nanoparticles (AgNPs) embedded in morin-formaldehyde/polyvinyl alcohol film (MFP-PVA) is introduced. The morin-formaldehyde polymer was synthesized and then added to PVA to construct a thin film for embedding AgNPs. The AgNPs were directly formed in the film based on the fast reduction of the AgNO3 using morin-formaldehyde at room temperature. The plasmon absorbance of AgNPs showed a notable change following interaction with Pd(II). As a result, the yellow color of the AgNPs in the film gradually decreased, which led to the development of a palladium monitoring probe. The characteristics of MFP-PVA film decorated by AgNPs were studied by field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The designed probe achieved good performance for Pd(II) analysis with a linear dynamic range of 0.47-23.5 μmol L-1 and a detection limit of 0.23 μmol L-1. The intra-day and inter-day relative standard deviation corresponding to eight replicate determinations of 0.94 and 18.8 μmol L-1 Pd(II) was less than 5 %. This method was used to analyze palladium in soil, industrial wastewater and palladium catalyst samples. A comparison of obtained results with ICP showed good agreement.