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Experimental probes of silver metal nanoparticle formation kinetics: Comparing indirect versus more direct methods
Author(s) -
Sandoe Haley E.,
Watzky Murielle A.,
Diaz Steven A.
Publication year - 2019
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.21315
Subject(s) - surface plasmon resonance , chemistry , nucleation , silver nanoparticle , kinetics , nanoparticle , reaction rate constant , kinetic energy , analytical chemistry (journal) , autocatalysis , spectroscopy , metal , nanotechnology , chromatography , materials science , catalysis , organic chemistry , physics , quantum mechanics
The kinetics of noble metal nanoparticle formation in bottom‐up syntheses are important for controlling and optimizing these methods. Hence, experimental probes that are easily accessible to most laboratories are also of interest. We collected kinetic curves for the formation of silver nanoparticles in a modified Turkevich method with citrate acting as the reducing and stabilizing agent by (i) measuring the change in silver nanoparticle surface plasmon resonance by UV‐visible spectroscopy, a somewhat indirect method, and then also by (ii) measuring the change in silver ion concentration by ion‐selective electrode potentiometry and/or atomic absorption spectroscopy, two more direct methods. The resulting sigmoidal kinetic curves were curvefitted with the Finke‐Watzky two‐step kinetic model of slow, continuous nucleation and fast autocatalytic growth to extract average rate constants. We found that the kinetic curves obtained by following the change in silver ion concentration were apparent mirror images of those constructed by following the change in nanoparticle surface plasmon resonance, and that their respective curvefits displayed the same sigmoidal characteristics. The resultant values of the rate constants for nucleation and growth overlapped within experimental error between the methods and showed similar trends over the range of citrate concentrations studied. The use of multiple probes in this work to follow the kinetics of nanoparticle formation helps fill a need for the comparison and evaluation of different methods available to scientists, particularly those considered easily accessible.