Presence of chlorpyrifos shows blue shift of the absorption peak of silver nanohexagons solution - An indication of etching of nanocrystals and sensing of chlorpyrifos

Here in this work, we have used synthesized silver nano-hexagon for the sensing of chlorpyrifos (CP) in water at very low ppm level. Silver nano-hexagons have been synthesized through chemical reduction method, using polyvinylpyrrolidone (PVP) as a capping agent, with an average size of around 50 nm. Colorimetric as well as spectrophotometric analysis show the sensing of chlorpyrifos at very low ppm level of 5 ppm, which is based on the surface plasmon resonance (SPR) of silver nanocrystals. It has been observed that on treating the CP with silver nano-hexagons solution, colourlessness of the silver solution take place, whereas spectrophotometric study show the blue shift as well as decrease of the intensity of SPR peak, confirming the etching of the silver nano-hexagons. The etching of silver nanocrystals is further found in the TEM images of the silver nanocrystals, after treatment with chlorpyrifos. Moreover, CP gets converted into 3,5,6-trichloro-2-pyridinol (TCP) via chlorpyrifos oxon much more faster on treating with silver nano-hexagon solution and the conversion has been confirmed from the UV/Visible spectra as well as Nuclear magnetic resonance (NMR) spectra.