Fig. 1

X-ray diffraction patterns of bare and coated ZnO-NPs. Sample 1: Bare ZnO-NPs showed typical peaks of the ZnO with a definite line broadening indicating the nano-scale with a mean crystal size of 25.8 nm. Sample 2: In situ prepared ZnO-NPs, using PEG-6000 as a surfactant and absolute ethanol as a co-surfactant, revealing the characteristic standard pattern of the ZnO-NPs with a crystal size of 28.7 nm. Sample 3: Ex-situ prepared ZnO-NPs using PEG 6000 as a stabilizer exhibiting a fine diffraction peak characteristic to the PEG (Arrow) and a definite line broadening indicate a smaller mean crystal size of 15.5 nm. Sample 4: In situ prepared ZnO-NPs coated with PEG-6000, after calcination, showing well-defined distinctive PEG diffraction peaks (stars) and mean particle size of 18 nm