GOwere synthesized using simplified Hummer’s
method (Huang et al. 2011). For surface modification, GO
was prepared by oxidation of graphite, H2SO4:H3PO4
(in the ratio of 320:80 mL) and 18 g KMnO4at room temperature.
The materials were mixed using magnetic stirrer for 3
days. Next, H2O2
was added to stop the oxidation process
and the resulting solution was washed with 1 M of HCl
for three times. Again, the solution obtained was washed
using deionized water via centrifugation until a pH of 4
was achieved.