GO, prepared from natural graphite by the modified Hummer’s method [17], was used as the starting material for the fabrication of Fe3O4/SiO2single bondGO NPs. First, a mixture of 0.5 g GO in 300 mL water was ultrasonicated for 2 h for GO exfoliation, and then 100 mg of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 80 mg of N-hydroxysuccinnimide (NHS) were added into the solution of the exfoliated GO. The above mixture was stirred for 30 min and ultrasonicated for another 30 min to form a homogenous suspension. Next, 0.5 g of Fe3O4/SiO2 NPs was added into the suspension, and the mixture was subjected to ultrasonication for 30 min. Finally, the reaction was carried out at 80 °C for 1 h under stirring. Fe3O4/SiO2single bondGO was obtained by magnetic separation and washed with water for several times.