Sixty milligrams of PDA/MS was dipped into a beaker containing 200 mL of the freshly AgNO3 solution (200 mg/L) for about 6 h, followed by washing with deionized water. Then, it was placed into 200 mL of NaBH4 solution (0.2 M) to carry out the process of restoring Ag+ to AgNPs. Finally, AgNPs/PDA/MS was acquired after disposing in a vacuum drying oven at 45 °C for 4 h.