Modeling silver nanoparticle synthesis via pulsed and RF plasma electrolysis*

In plasma-driven solution electrochemistry (PDSE), charged species and radicals are first produced in a gas phase plasma, subsequently solvate into an interfacing liquid solution, and finally act as initiators for material synthesis. PDSE has the advantage over conventional electrolysis in being able to produce controllable and large fluxes of electrons into the surface of the solution that are then available for reduction processes.  One such process is the reduction of silver cations in solution for the formation of nanoparticles. The PDSE of AgNO₃ via an atmospheric pressure plasma jet for formation of silver nanoparticles was computationally investigated using the 0-D plasma kinetics model, GlobalKin, and the 2-D multi-fluid hydrodynamics model nonPDPSIM. The fundamental solution reaction mechanism was developed based on ab initio calculations of the formation of cation and neutral silver clusters.  Results from the model are compared with experimental measurements. The parameter space was varied to quantify the relative importance of electrical boundary conditions, aqueous solution type (e.g. water vs ionic liquid), and excitation method (pulsed vs RF voltage) on Ag⁺ reduction.