Fig. 3. (a–e) Selective reductive amination of various aldehydes and ketones over Co@CoO_x, CoCu@CoCuO_x and Cu@CuO_x catalysts. (f) Catalyst recycling for CoCu@CoCuO_x. Reaction conditions: substrate 0.24 mmol, N₂H₄·H₂O 2 mmol, catalyst 30 mg, methanol 4 mL, 3 MPa H₂, 30 °C.