Construction of rGO wrapping Cu2O/ZnO heterostructure photocatalyst for PNP and PAM degradation

Copper and zinc composite oxides (Cu2O/ZnO) were synthesized by an impregnation-reduction-air oxidation method. A series of Cu2O/ZnO/rGO ternary composites were prepared by coupling with graphene oxide (GO) with different mass fractions in a solvothermal reaction system. The microscopic morphology, crystal structure, and optical characteristics of the photocatalysts were characterized. The degradation of p-Nitrophenol (PNP) and polyacrylamide (PAM) by photocatalytic materials under simulated solar irradiation were studied, and the degradation kinetics were also investigated. The results showed that cubic Cu2O was modified by ZnO nanorods and distributed on rGO nanosheets. The ternary Cu2O/ZnO/rGO nanocomposites have stronger simulated solar absorption ability and higher photodegradation efficiency than pure ZnO and binary Cu2O/ZnO nanocomposites. When the amount of Cu2O/ZnO/rGO-10 was 0.3 g L-1, the degradation rate of 10 mg L-1 PNP reached 98% at 90 min and 99.6% of 100 mg L-1 PAM at 30 min. The photocatalytic degradation processes of PNP and PAM all followed the pseudo-first-order kinetic model. Free radical trapping experiments showed that superoxide radicals were the main active substances to improve photocatalytic efficiency. In addition, after four recycles, the catalytic efficiency of Cu2O/ZnO/rGO-10 was still over 90%. It showed that Cu2O/ZnO/rGO-10 was a promising catalyst for wastewater treatment because of its good photostability and reusability.