Synthesis of metal nanoparticles by dual plasma electrolysis using atmospheric dc glow discharge in contact with liquid

Abstract

For the synthesis of metal nanoparticles in aqueous solution, we propose dual plasma electrolysis, which consists of a Hoffman electrolysis apparatus with two atmospheric glow discharge plasmas as electrodes instead of conventional metal electrodes immersed in a liquid. The plasma anode irradiates positive ions to the solution surface while the plasma cathode irradiates electrons to the solution surface. The dual plasma electrolysis system enables us to simultaneously investigate the influence of electron and positive ion irradiation to a solution surface on metal nanoparticle generation at the same current. In this work, we used aqueous solutions of AgNO3, HAuCl4, and their mixture. In dual plasma electrolysis with AgNO3, Ag nanoparticles were only synthesized on the plasma cathode side. This means that Ag nanoparticles are generated via the reduction of Ag+ by electrons. With HAuCl4 solution, Au nanoparticles were synthesized on both the plasma anode and plasma cathode sides. Ion irradiation with the plasma anode is more effective than electron irradiation for Au nanoparticle synthesis. This finding suggests that positive ions from the plasma trigger the dissociative reaction of AuCl4 − at the plasma–liquid interface. When a AgNO3–HAuCl4 mixture was used, the synthesized nanoparticles have a structure consisting of a Au core covered with a Ag shell.

A review of plasma–liquid interactions for nanomaterial synthesis

“…They attributed the NPs formation to the plasmaprovided-electron reduction of Au or Ag ions either from the anodic dissolution or the pristine metal salt solutions. Recently, a similar experiment has been performed by replacing the immersed metal anode with a plasma [154][155][156]. As shown in Fig.…”

Predictor Packing in Developing Unprecedented Shaped Colloidal Particles

“…Mainly, four approaches remained under operation: (1) DC plasma discharge in contact to liquid [26][27][28][29], (2) DC glow discharge plasma in contact to liquid [30], (3) pulse plasma discharge inside the liquid [31][32][33][34][35][36], and (4) gas-liquid interface discharge [37]. Hydrogen peroxide was the most probable reaction mechanism to synthesize gold nanoparticles [26][27][28][29].…”

Predictor Packing in Developing Unprecedented Shaped Colloidal Particles<strong> </strong>

“…Mainly, four approaches remained under operation: (1) DC plasma discharge in contact to liquid [26][27][28][29], (2) DC glow discharge plasma in contact to liquid [30], (3) pulse plasma discharge inside the liquid [31][32][33][34][35][36], and (4) gas-liquid interface discharge [37]. Hydrogen peroxide was the 5 most probable reaction mechanism to synthesize gold nanoparticles and aqueous electrons to drive the process [26][27][28][29].…”