Controllable electrochemical synthesis of Ag nanoparticles in ionic liquid microemulsions

• A continuous controllable electrochemical synthesis of Ag nanoparticles measuring 2 ~ 13 nm
• The electrochemical reduction occurred in the microreactors of the ILM, did not on the cathode surface
• A new quaternary ionic liquid microemulsion
• IL acts as a co-surfactant for the formation of micro-reactors and an electron carrier from the cathode to the aqueous phase

Continuous and controllable synthesis of nanoparticles in solution without agglomeration has long been a scientific and technological challenge. In this study, controllable electrochemical synthesis of Ag nanoparticles of diameters 2–13 nm has been achieved in a novel quaternary ionic liquid microemulsion (ILM). The ionic liquid, 1-butyl-3-methyl-imidazolium chloride ([BMIM]Cl), acts not only as a soft template and co-surfactant for the formation of micro-reactors, but also an electron carrier from the cathode to the aqueous phase of micelles, leading to the electrochemical reduction of AgBr in microemulsions. The size and distribution of the Ag nanoparticles can be tuned by varying electrodeposition conditions, the type of ionic liquids and surfactant concentrations. A mechanism for the electrochemical synthesis of Ag nanoparticles in the quaternary ionic liquid microemulsions is also proposed.