Ionic Liquids as an Efficient Reaction Medium in the Robust Synthesis of ZnO Nanoparticles

Abstract

Ionic liquids belong to the class of green solvents and are distinguished by their simple yet distinctive physical properties that are related to their structure. These properties include their remarkable thermal stability, exceptional thermal conductivity, and negligible vapor pressure. Additionally, they are suitable and inert for a wide range of catalytic applications. Zinc Oxide Nanoparticles (ZnO-NPs) have been considered a cost-effective choice that requires modest reaction conditions to provide a high yield of the required products with remarkable selectivity in a short amount of time. Consequently, an investigation into the synthesis of ZnO-NPs in an ionic liquid medium has been attempted in the current work. The synthesis of metal nanoparticles using highly tunable ionic liquids is being investigated for many pharmacological applications and their usage in catalysis. In this context, the current work has used the co-precipitation approach to synthesize ZnO-NPs. The production of ZnO nanoparticles with a range of morphologies utilizing an imidazolium ionic liquid system has been the main topic of discussion. The co-precipitation method has successfully been administered for the synthesis of morphologically diverse nano-crystalline ZnO particles using different ionic liquids, such as 1-propyl- 3-methylimidazolium bromide (pmim)(Br), 1-butyl-3-methylimidazolium bromide ([bmim][Br]), and 1-hexyl-3-methylimidazolium bromide (hmim)(Br) as an additive Modern analytical tools, including X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and FT-IR absorption spectroscopy have been employed to confirm the structure of these ZnO nanoparticles. The IR absorption peak below 480 cm-1 and the XRD pattern showed all the peaks in the diffraction diagram, revealing the formation of ZnO-NPs. FE-SEM images showed various morphologies of ZnO-NPs and they have been found to be separated from the agglomerated clusters. The characteristic results have revealed ionic liquids to have substantial effects on the size of the zinc nano-species as well as provide the appropriate environment for the growth of the nanoparticles.