Fig. 3
FT-IR spectra of bare and coated ZnO-NPs samples. Sample 1: Bare ZnO-NPs illustrate significant absorption peaks at ~ 3453, 1653, and 432 cm−1 (red arrows) that is characteristic to ZnO. Sample 2: In situ synthesized ZnO-NPs using PEG-6000 as a stabilizer and ethanol as co-surfactant exhibiting intense absorption peaks at ~ 1006, 1362, 1473, and 2877 cm− 1 (red arrows) confirming the existence of polymer molecules and metal oxides. Sample 3: Ex-situ synthesized ZnO-NPs using PEG-6000 as a stabilizer, showing absorption peaks of low intensity at ~ 1522, 2860, and 2926 cm− 1. Sample 4: The in situ prepared ZnO-NPs coated with PEG-6000 showing an assignment similar to sample 2