MgO NP and TEM observations 97
MgO NPs (UCM250) were obtained from Ube Material Industries. In all experiments, MgO 98
NPs were suspended in distilled water, and the suspension was ultrasonicated for 5 min 99
before use. For transmission electron microscope (TEM) observation, MgO NPs (5 mg) were 100
mixed with 99% ethanol (10 mL). Samples were mounted on regular hexagonal copper grids. 101
TEM observation was carried out using a JEM-2100 (JEOL) at an acceleration voltage of 200 102
kV.