Effect of dicationic ionic Liquid: Trimethylene bis-methylimidazolium bromide ([M(CH2)3IM2+][2Br-]) on the structural, optical and morphological properties of ZnO nanoparticles

[Display omitted] •Effect of the reaction media on the properties of ZnO nanoparticles (ZnO NPs).•ZnO NPs synthesized by the conventional method (ZnO-S) and samples elaborated in an ionic liquid (IL) media (ZnO-IL).•XRD, FTIR, UV–VIS and TEM measurements.•The ionic liquid (IL) is a very advantageous reaction media for directing a chemical transformation.•Diluted media of ([M(CH2)3IM2+][2Br-]) can be decisive concerning the sizes and the morphologies of the obtained ZnO NPs. In this work, we make a comparative study between ZnO nanoparticles samples (NPs) synthesized by the conventional method (ZnO-S) and samples elaborated in an ionic liquid (IL) media (ZnO-IL) to see the effect of the latter on the structural, optical and morphological properties of these NPs. The results of this study are obtained using the following characterization methods: X-ray diffraction for the study of the structural properties of the different ZnO NPs samples, infrared spectroscopy (FTIR) to determine the nature of the different bonds present in our samples, UV–Visible spectrometry to determine the gap energy of zinc oxide. The results of Transmission Electron Microscopy have also been reported to show the effect of ionic liquid on the morphology of ZnO NPs. The XRD allowed us to see the effect of ionic liquid on the size of the crystallites manifested by a noticeable decrease. The curves of the UV–Vis show that the value of the gap energy is not the same for the two samples of ZnO-S and ZnO-IL, which implies that the latter has been influenced by the change in the reaction media. Transmission electron microscopy shows that the ionic liquid influences the size of the nanoparticles, there are two populations of nanoparticles, the first between (50 and 100 nm) as for ZnO-S NPs and a second in the order of 20 nm, which implies that the presence of the ionic liquid reduced the size of the NPs. We conclude that ionic liquid can be very useful to control the size of ZnO NPs and the appearance of novel properties.