TEM Imaging of ZnO Nanoparticles

ZnO-NPs were imaged using TEM (H-700, Hitachi Ltd., Tokyo, Japan) at an accelerated voltage of 80 kv using a negative staining method following our previously published protocol [2 (link),7 (link)]. Briefly, the sample was diluted (1:50) with double-distilled water and then a drop of the diluted sample was applied to a mesh copper grid coated with a carbon film and was left to dry for 5 min. After this, a drop of the phospho-tungstic acid solution (2% w/w) was added to the grid for 50 s and the excess liquid was removed using filter paper. The grid was left to air-dry in advance of imaging. TEM imaging was performed for the identification of the sample’s uniformity, shape, size, and presence of any aggregation.