Fig. 5. (a) Photocatalytic activity and (b) ln(C₀/C) vs. time plot for photodegradation of MB with different concentration from 5–25 mg L⁻¹; (c) photocatalytic degradation percentage of MB with different amount of H₂O₂ (1#, 0.03 mL H₂O₂; 2#–7#, 9 mg Cu₂O–Cu with 0, 0.01 mL, 0.02 mL, 0.03 mL, 0.04 mL, 0.05 mL H₂O₂, respectively); (d) ln(C₀/C) vs. time plot for MB photodegradation with 30 μL H₂O₂ only, 30 uL H₂O₂ and photocatalyst.