I'm synthesising silver nanoparticles using bacterial cellulose as the reducing agent, using only AgNO3 and the membrane itself. After UV-Vis analysis i get the SPR peak well defined, but get as well other peak at around 270nm. Could it be nanoclusters or remains of the salt precursor? Thanks in advance,
Regards.
It may be due the reducing agent which will disappear gradually after the formation of Silver nanoparticles
To my knowledge, the SPR peaks occur due to the electrons transitions resulted from energetic excitations from the light source in the UV-Vis spectroscopy. So, different wavelengths (different energy) means different electrons excitations causing more than one SPR peak.
During the normal syntheses of Ag-nanoparticles (with organic/inorganic compounds) the additional peaks between 200-350 nm are attributed to various ligand centered transitions like pi-pi* or n-pi*. But, being specific in your case, such transitions might be attributed to the transitions associated to the bacterial cellulose.
you check the XRD pattern of your product. The additional peak is may be due to the formation AgCl nanoparticles over the AgNP.
Mr.Arnab Biswas is correct. Generally in the biosynthesis of nanoparticles, the biomolecules get attached to NPs and intense peaks due to this can be observed in UV-vis spectrum.
That is why we have to run plant extract alone and after synthesising Ag NP using plant we have to UV_ Visible pattern.
Plant extracts generally display peak in the region. It’s proved in many cases.
Membrane without any nanoparticles spectrum was observed as well, and did not show any peak near that wavelenght region. However, membranes impregnated with AgNO3 solution (without any particles formed, just the salt) showed a peak near 300nm, which can be related to the silver oxidation and/or nanoclusters.
It may be due the reducing agent which will disappear gradually after the formation of Silver nanoparticles
This can be related to the electronic transition for Ag ions and confirmed that not all Ag ions are reduced to NPs
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