Green synthesis and growth kinetics of nanosilver under bio-diversified plant extracts influence

In this report, synthesis, growth and formation kinetics of silver nanoparticles mediated by various plant extracts in their biodiversity have been monitored using UV-Vis spectrophotometer by sampling at time intervals during bioreduction process. Plasmon band resonance of the silver nanoparticles was observed as the reaction progresses indicating nucleation and particle formation. There were cases of red shifting indicating particle size increase. In the bioreduction process, onset of nanoparticle nucleation and growth were observed within 2, 5, 10 or 30 min and eventual formation of spherical or quazi-spherical amidst twinned morphology as determined by transmission electron microscope (TEM). The nanosilver growth kinetics mechanism has been probed using a time-resolved UV-Vis in conjunction with TEM following existing Lifshitz-Slyozov-Wagner theory. For some biological extract-mediated synthesis, a single-stage mechanism that is diffusion controlled following Ostwald ripening (OR) is proposed. Whereas, for other bioreduction process, a double stage involving (1) initial OR followed by (2) surface adsorption-oriented attachment is proposed for temporal evolution of the nanosilver in green environment.