100 mg of COFs (e.g., COF-1, COF-2, and COF-3) and 100 mg of PdCl2 were dispersed in 20 mL of distilled water via ultrasonication (for 30 min) and stirred overnight (10 h). Then, a methanol solution of sodium borohydride (NaBH4) was added to the suspension and stirred further at room temperature for one hour . A black precipitate was filtered and washed with methanol (1×20 mL) and water (2×20 mL). The materials were dried under vacuum for 24 h at 80 o C.