When nanoparticles are synthesized by chemical reduction, how does the size, shape, and concentration of the nanoparticles change with the change in concentration of reducing agent?
Question is very broad.. dozens of review articles on this topic..
Besides the factors stated by Ms.Rana, pH & zeta potential of the reaction medium also plays a critical role especially in synthesis of noble metal NPs
Reducing agents influence the size and shape of nanoparticles, since they define the pressure of the reaction, during their decomposition.
If the reaction pressure is high, the reaction rate is greatly accelerated, and the process of nucleation and growth of the nanoparticles will be highly accelerated,and the opposite effect will occur if the pressure is low, thus prepared nanoparticles have various shapes and sizes.
I agree with Sridhar, the question is too broad. You should initially consider that a low concentration of reducing agent, reduction this will not be effective. If you increase the concentration of reducing agent, nucleation is favored and increase the diameters, also all depends on the agent used and as Ms. Rana says there is also the influence of temperature, solvent, use of stabilizing agent, etc..
see articles of Philippot, Rocoux, Chaudret
It depends not only on the reducing agent concentration but also in it strength. Generally if the reducing agent is strong (such us NaBH4) and it concentration is high, the size of the resulting nanoparticles will be small. When you are working with weak reducing agents it is quite difficult to answer your question. The size and shape of the produced nanoparticles depends on the experimental conditions and the batch composition (surfactant free or not, additives, precursors nature and concentrations, etc.)
I can answer in one way: it is not trivial. I read in the past about theory supporting that slower reduction it is better than fast ones and viceversa (a kinetic reaction point of view: reagent concentration, temperature...). I think there is not an unique way to answer. For example for gold nanoparticles their natural tendence to aggregation found a solution on the utilisation of surfactants...Moreover, if you are looking for to obtain nanoparticles supported the support plays an important role. At the sum it is not trivial and I think doesn't exist an unique answer.
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