Ag₂S interparticle interaction in an aqueous solution: Mechanism of steric and electrostatic stabilization

In this study, two types of stable Ag₂S nanoparticle solutions with negative and positive zeta-potential and different stabilization mechanisms were synthesized by a chemical precipitation method. The first type was stabilized by adding 3-mercaptopropyl-trimethoxysilane (MPS) to provide steric stability of nanoparticles. It was found, that the MPS molecules could effectively stabilize the system covering about 20% of the nanoparticle's surface. For the second type, a simple method suggested in this work was used for the first time. This novel method is based on the addition of Na₂S in great excess, which induces electrostatic stability of the solution with nanoparticles. The correlation between stability and parameters of nanoparticles has been established.