During the synthesis of silver nanoparticles, we ended with a brown colored solution, which turned into a black colored solution with further procedure. What is the reason for this? How could this be avoided? Can use sonicator to remove the agglomeration if any during the synthesis of silver nanoparticles?
It depend upon the preparation method. But any way, you can prevent the agglomeration by using stabilizing agent (a strongly absorbed monolayer of usually organic molecules used to aid stabiliztion of nanoparticles).
It is generally due to particles aggregation. Many factors may play a role (absence of stabilizing agent such as surfactant or polymers, large particles dimension, high temperature, fast mixing or wrong solvent). As already suggested it depend on the synthetic method. Once destabilized it is generally very difficult or not possible to redisperse the particles because of the high surface to volume ratio.
What is the method used for synthesis? You may use trisodium citrate as a stabilizing agent
The preparation method depends mainly on the nature of application of the Ag nanoparticles. Anyway using microwave techniques for synthesis is a great advantage because of small reaction time and using a stabilising agent like PVP will help to reduce agglomeration to a great extent.
Thank You
Its because of the metallic Ag. You have use surfactant, ligand which can prevent bacl colour formation
Dear sir, we are synthesizing the Ag nanoparticles by chemical route method. We are using Silver Nitrate and TriSodium Citrate as precusors.
It is due to the air oxidation of AgNPs resulting to form silver oxide. Do you reaction in N2/Ar gas free from oxygen also use any stabilizing agent like PEG/MUA. Hope you will not get this problem again.
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