Preparation and photocatalytic "memory" effect of Cu-Cu2O/SnO2 composite

The photocatalyst with photocatalytic "memory" effect can solve the inherent activity loss of traditional photocatalysts when the light is turned off, which would greatly improve its catalytic efficiency in the field of wastewater treatment. In this work, Cu-Cu2O/SnO2 composites with different SnO2 contents were prepared by adding different amounts of SnO2 colloidal solution to Cu-Cu2O suspension via a solvothermal method. The product was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, zeta potential, transient photocurrent response and electrochemical impedance spectroscopy. The photocatalytic activity and "memory" effect of Cu-Cu2O/SnO2 composite were investigated through methyl orange (MO) solution degradation experiments. The results show that the Cu-Cu2O/SnO2 of Sn0.75 sample possesses the best photocatalytic performance and the degradation rate of MO is 93.7% under visible light for 120 min. Furthermore, the removal rate of methyl orange solution is increased by 17.2% in dark for 3 h after the Sn0.75 photocatalyst is illuminated for 1 h, which displays that the Cu-Cu2O/SnO2 photocatalyst possesses the post-illumination "memory" activity. This work will provide an experimental basis for highly efficient round-the-clock photocatalysts.