Experimental study on the preparation of monodisperse nano-silver by hydrothermal synthesis

As a new material with wide application prospect, nano-silver is getting high attention. Hydrothermal synthesis has the advantages of green, easy operation and low cost, and is a promising technology for the preparation of nano-silver. In this paper, the effects of reaction time, reaction temperature, precursor concentration, PVP concentration and modifier addition on the particle size distribution and surface morphology of nano-silver during the subcritical hydrothermal reaction were optimized by comparing the supercritical and subcritical hydrothermal methods. Then, the important role and reaction mechanism of PVP as a modifier and the formation mechanism of spherical nano-silver particles were analyzed. The experimental results showed that the average particle size of 23.68 nm can be obtained by using NaHCO₃ and PVP as reducing and dispersing agents, the reaction time is 5 h, the reaction temperature is 180 °C, and the concentrations of AgNO₃ and PVP are 0.1 M and 0.3 M, respectively, to obtain the more uniformly dispersed silver nanoparticles. The results provide an important reference for future research on the preparation of conductive pastes.