Electrochemical Synthesis of ZnO Nanopowder Involving Choline Chloride Based Ionic Liquids

Abstract

The paper presents some preliminary experimental results regarding the electrochemical synthesis of ZnO nanopowders through anodic dissolution of Zn metal in choline chloride based ionic liquids. Electrolytes consisting in 10 mM Zn(CH₃COO)₂x2H₂O dissolved in choline chloride-ethylene glycol or choline chloride-urea eutectic mixtures have been involved, with additions of 1-2 mL/L H₂O₂ 30%. Current densities between 15 and 50 mA cm^-2 were applied at electrolyte temperatures of 20-30 °C for durations between 3 and 5 h. XRD investigations showed the hexagonal wurtzite structure of ZnO, in agreement with otherliterature data. Crystallites average sizes of 12-18 nm have been determined for the anodically synthesized ZnO nanopowders. The addition of either TBAB or PVP determined a slight increase of crystallites sizes, from around 12-13 nm towards about 18 nm. According to SEM micrographs, the nanoparticles are approaching spherical shape with a slight agglomeration state, due to their small size.
The influence of the addition of different additives, such as tetrabutylammonium bromide or polyvinylpyrrolidone on the electro-synthesized ZnO nanopowder characteristics is also discussed.