*2.2. Synthesis of AGO*

GO powder (~200 mg) was dispersed in *N*,*N*-dimethylformamide (DMF) by ultrasonication. The mixture was mechanically stirred at 30 ◦C for 1 h and then slowly dropped into ethylenediamine (EDA, 300 mL) under rapid stirring. The reaction was allowed to proceed for 24–48 h under nitrogen protection. After the reaction, the mixture was diluted in ethanol (1600 mL) and washed several times to ensure the removal of excess EDA. Finally, AGO could be collected after filtration and dried overnight in a vacuum oven at 50 ◦C [13–15].
